Space is the expanse that exists beyond Earth and between celestial bodies. Outer space is not
completely empty—it is a hard vacuum containing a low density of particles, predominantly a
plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos,
dust, and cosmic rays. The baseline temperature of outer space, as set by the background radiation
from the Big Bang, is 2.7 kelvins (−270.45 °C; −454.81 °F). The plasma between galaxies is thought
to account for about half of the baryonic (ordinary) matter in the universe, having a number
density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins.
Local concentrations of matter have condensed into stars and galaxies. Studies indicate that 90%
of the mass in most galaxies is in an unknown form, called dark matter, which interacts with
other matter through gravitational but not electromagnetic forces. Observations suggest that the
majority of the mass-energy in the observable universe is dark energy, a type of vacuum energy that
is poorly understood. Intergalactic space takes up most of the volume of the universe, but even
galaxies and star systems consist almost entirely of empty space.
Outer space does not begin at a definite altitude above the Earth's surface. The Kármán line, an
altitude of 100 km (62 mi) above sea level, is conventionally used as the start of outer space in
space treaties and for aerospace records keeping. The framework for international space law was
established by the Outer Space Treaty, which entered into force on 10 October 1967. This treaty
precludes any claims of national sovereignty and permits all states to freely explore outer space.
Despite the drafting of UN resolutions for the peaceful uses of outer space, anti-satellite weapons
have been tested in Earth orbit.
Humans began the physical exploration of space during the 20th century with the advent of high-altitude
balloon flights. This was followed by crewed rocket flights and, then, crewed Earth orbit, first achieved
by Yuri Gagarin of the Soviet Union in 1961. Due to the high cost of getting into space, human spaceflight
has been limited to low Earth orbit and the Moon. On the other hand, uncrewed spacecraft have reached all
of the known planets in the Solar System.
Outer space represents a challenging environment for human exploration because of the hazards of vacuum
and radiation. Microgravity also has a negative effect on human physiology that causes both muscle atrophy
and bone loss. In addition to these health and environmental issues, the economic cost of putting objects,
including humans, into space is very high.
The universe is a huge wide-open space that holds everything including the smallest particle to
the largest galaxy.No one knows how big the universe is. It is about 13.8 billion years old.
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly.
Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, the
dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the natural satellites—two are larger
than the smallest planet, Mercury.
The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The
vast majority of the system's mass is in the Sun, with the majority of the remaining mass contained in Jupiter. The four
smaller inner system planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and
metal. The four outer system planets are giant planets, being substantially more massive than the terrestrials. The two largest
planets, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus
and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and
helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a
nearly flat disc called the ecliptic.
The Solar System also contains smaller objects. The asteroid belt, which lies between the orbits of Mars and Jupiter, mostly
contains objects composed, like the terrestrial planets, of rock and metal. Beyond Neptune's orbit lie the Kuiper belt and
scattered disc, which are populations of trans-Neptunian objects composed mostly of ices, and beyond them a newly discovered
population of sednoids. Within these populations, some objects are large enough to have rounded under their own gravity,
though there is considerable debate as to how many there will prove to be. Such objects are categorized as dwarf planets.
The only certain dwarf planet is Pluto, with another trans-Neptunian object, Eris, expected to be, and the asteroid Ceres
at least close to being a dwarf planet. In addition to these two regions, various other small-body populations, including
comets, centaurs and interplanetary dust clouds, freely travel between regions. Six of the planets, the six largest possible
dwarf planets, and many of the smaller bodies are orbited by natural satellites, usually termed "moons" after the Moon. Each
of the outer planets is encircled by planetary rings of dust and other small objects.
The solar wind, a stream of charged particles flowing outwards from the Sun, creates a bubble-like region in the interstellar
medium known as the heliosphere. The heliopause is the point at which pressure from the solar wind is equal to the opposing
pressure of the interstellar medium; it extends out to the edge of the scattered disc. The Oort cloud, which is thought to be
the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere. The
Solar System is located 26,000 light-years from the center of the Milky Way galaxy in the Orion Arm, which contains most of the
visible stars in the night sky. The nearest stars are within the so-called Local Bubble, with the closest Proxima Centauri at
4.25 light-years.
The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core,
radiating the energy mainly as visible light, ultraviolet light, and infrared radiation. It is by far the most important source of energy for life on Earth. Its diameter
is about 1.39 million kilometres (864,000 miles), or 109 times that of Earth. Its mass is about 330,000 times that of Earth; it accounts for about 99.86% of the total
mass of the Solar System. Roughly three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier
elements, including oxygen, carbon, neon and iron. |
Sun-scorched Mercury, the smallest planet in our solar system, is only slightly larger than Earth's moon. Like the moon, Mercury has very little atmosphere to stop impacts
and it is covered with craters. Mercury's dayside is super-heated by the sun, but at night temperatures drop hundreds of degrees below freezing. Ice may even exist in craters. |
Venus is a dim world of intense heat and volcanic activity. Similar in structure and size to Earth, Venus' thick, toxic atmosphere traps heat in a runaway 'greenhouse effect.'
The scorched world has temperatures hot enough to melt lead. Glimpses below the clouds reveal volcanoes and deformed mountains. Venus spins slowly in the opposite direction of
most planets. |
Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. About 29.2% of Earth's surface is land consisting of continents and
islands. The remaining 70.8% is covered with water, mostly by oceans, seas, gulfs, and other salt-water bodies, but also by lakes, rivers, and other freshwater, which together
constitute the hydrosphere. Much of Earth's polar regions are covered in ice. Earth's outer layer is divided into several rigid tectonic plates that migrate across the surface
over many millions of years, while its interior remains active with a solid iron inner core, a liquid outer core that generates Earth's magnetic field, and a convective mantle
that drives plate tectonics.Earth's atmosphere consists mostly of nitrogen and oxygen. More solar energy is received by tropical regions than polar regions and is redistributed
by atmospheric and ocean circulation. Greenhouse gases also play an important role in regulating the surface temperature. A region's climate is not only determined by latitude,
but also by elevation and proximity to moderating oceans, among other factors. Severe weather, such as tropical cyclones, thunderstorms, and heatwaves, occurs in most areas and
greatly impacts life. |
The Moon is Earth's only natural satellite. At about one-quarter the diameter of Earth (comparable to the width of Australia), it is the largest natural satellite in the Solar System relative to the size of its planet, the fifth largest satellite in the Solar System overall, and is larger than any known dwarf planet. Orbiting Earth at an average distance of 384,400 km (238,900 mi), or about 30 times Earth's diameter, its gravitational influence slightly lengthens Earth's day and is the main driver of Earth's tides. The Moon is classified as a planetary-mass object and a differentiated rocky body, and lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's (0.1654 g); Jupiter's moon Io is the only satellite in the Solar System known to have a higher surface gravity and density.
The Moon's orbit around Earth has a sidereal period of 27.3 days. During each synodic period of 29.5 days, the amount of visible surface illuminated by the Sun varies from none up to 100%, resulting in lunar phases that form the basis for the months of a lunar calendar. The Moon is tidally locked to Earth, which means that the length of a full rotation of the Moon on its own axis causes its same side (the near side) to always face Earth, and the somewhat longer lunar day is the same as the synodic period. That said, 59% of the total lunar surface can be seen from Earth through shifts in perspective due to libration.
The most widely accepted origin explanation posits that the Moon formed about 4.51 billion years ago, not long after Earth, out of the debris from a giant impact between the planet and a hypothesized Mars-sized body called Theia. It then receded to a wider orbit because of tidal interaction with the Earth. The near side of the Moon is marked by dark volcanic maria ("seas"), which fill the spaces between bright ancient crustal highlands and prominent impact craters. Most of the large impact basins and mare surfaces were in place by the end of the Imbrian period, some three billion years ago. The lunar surface is relatively non-reflective, with a reflectance just slightly brighter than that of worn asphalt. However, because it has a large angular diameter, the full moon is the brightest celestial object in the night sky. The Moon's apparent size is nearly the same as that of the Sun, allowing it to cover the Sun almost completely during a total solar eclipse.
Both the Moon's prominence in the earthly sky and its regular cycle of phases have provided cultural references and influences for human societies throughout history. Such influences can be found in language, calendar systems, art, and mythology. The first artificial object to reach the Moon was the Soviet Union's Luna 2 uncrewed spacecraft in 1959; this was followed by the first successful soft landing by Luna 9 in 1966. The only human lunar missions to date have been those of the United States' Apollo program, which landed twelve men on the surface between 1969 and 1972. These and later uncrewed missions returned lunar rocks that have been used to develop a detailed geological understanding of the Moon's origins, internal structure, and subsequent history.
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, being larger than only Mercury. In English, Mars carries the name of the Roman god
of war and is often referred to as the "Red Planet". The latter refers to the effect of the iron oxide prevalent on Mars's surface, which gives it a reddish appearance distinctive
among the astronomical bodies visible to the naked eye. Mars is a terrestrial planet with a thin atmosphere, with surface features reminiscent of the impact craters of the Moon and
the valleys, deserts and polar ice caps of Earth. |
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the
Solar System combined, but slightly less than one-thousandth the mass of the Sun. Jupiter is the third-brightest natural object in the Earth's night sky after the Moon and Venus.
It has been observed since pre-historic times and is named after the Roman god Jupiter, the king of the gods, because of its observed size. |
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times
that of Earth It only has one-eighth the average density of Earth; however, with its larger volume, Saturn is over 95 times more massive. Saturn is named after the Roman god
of wealth and agriculture; its astronomical symbol represents the god's sickle. The Romans named the seventh day of the week Saturday, Sāturni dies ("Saturn's Day") for the
planet Saturn. |
Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus, who, according to Greek mythology, was the great-grandfather of Ares
(Mars), grandfather of Zeus (Jupiter) and father of Cronus (Saturn). It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Uranus is
similar in composition to Neptune, and both have bulk chemical compositions which differ from that of the larger gas giants Jupiter and Saturn. For this reason, scientists often
classify Uranus and Neptune as "ice giants" to distinguish them from the other giant planets. Uranus's atmosphere is similar to Jupiter's and Saturn's in its primary composition
of hydrogen and helium, but it contains more "ices" such as water, ammonia, and methane, along with traces of other hydrocarbons. It has the coldest planetary atmosphere in the
Solar System, with a minimum temperature of 49 K (−224 °C; −371 °F), and has a complex, layered cloud structure with water thought to make up the lowest clouds and methane the
uppermost layer of clouds The interior of Uranus is mainly composed of ices and rock. |
Neptune is the eighth and farthest known Solar planet from the Sun. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the
densest giant planet. It is 17 times the mass of Earth, slightly more massive than its near-twin Uranus. Neptune is denser and physically smaller than Uranus because its greater
mass causes more gravitational compression of its atmosphere. The planet orbits the Sun once every 164.8 years at an average distance of 30.1 AU (4.5 billion km; 2.8 billion mi).
It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the god Neptune's trident or the Greek letter psi. |
1. Asteroids are small rocky bodies that revolve around the sun.
2. They range in size from a few meters to more than 900 kilometers in diameter.
3. Asteroids have irregular shapes, but some are spherical, or round.
4.Most asteroids orbit the sun in asteroid belt.
5. The asteroid belt orbits between Mars and Jupiter.
6.Asteroids are thought to be left over from the formation of the solar system.
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly
shaped bodies, of many sizes but much smaller than planets, called asteroids or minor planets. This asteroid belt is also called the main asteroid belt or main belt to distinguish
it from other asteroid populations in the Solar System such as near-Earth asteroids and trojan asteroids.
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The asteroid belt is the smallest and innermost known circumstellar disc in the Solar System. About half its mass is contained in the four largest asteroids: Ceres, Vesta, Pallas,
and Hygiea. The total mass of the asteroid belt is approximately 4% that of the Moon. Ceres, the only object in the asteroid belt large enough to be a dwarf planet, is about 950 km in diameter, whereas Vesta, Pallas, and Hygiea have mean diameters of less than 600 km. The remaining bodies range down to the size of a dust particle. The asteroid material is so thinly distributed that numerous unmanned spacecraft have traversed it without incident. Nonetheless, collisions between large asteroids do occur, and these can produce an asteroid family whose members have similar orbital characteristics and compositions. Individual asteroids within the asteroid belt are categorized by their spectra, with most falling into three basic groups: carbonaceous (C-type), silicate (S-type), and metal-rich (M-type). The asteroid belt formed from the primordial solar nebula as a group of planetesimals. Planetesimals are the smaller precursors of the protoplanets. Between Mars and Jupiter, however, gravitational perturbations from Jupiter imbued the protoplanets with too much orbital energy for them to accrete into a planet. Collisions became too violent, and instead of fusing together, the planetesimals and most of the protoplanets shattered. As a result, 99.9% of the asteroid belt's original mass was lost in the first 100 million years of the Solar System's history. Some fragments eventually found their way into the inner Solar System, leading to meteorite impacts with the inner planets. Asteroid orbits continue to be appreciably perturbed whenever their period of revolution about the Sun forms an orbital resonance with Jupiter. At these orbital distances, a Kirkwood gap occurs as they are swept into other orbits. Classes of small Solar System bodies in other regions are the near-Earth objects, the centaurs, the Kuiper belt objects, the scattered disc objects, the sednoids, and the Oort cloud objects. On 22 January 2014, ESA scientists reported the detection, for the first definitive time, of water vapor on Ceres, the largest object in the asteroid belt. The detection was made by using the far-infrared abilities of the Herschel Space Observatory. The finding was unexpected because comets, not asteroids, are typically considered to "sprout jets and plumes". According to one of the scientists, "The lines are becoming more and more blurred between comets and asteroids". |
What are dwarf planets?
Dwarf planets are celestial objects that:
• orbit a star
• are roughly spherical
• often have many other large bodies such as comets, asteroids, or other dwarf planets near them
As their name suggests, the main difference between a dwarf planet and a planet is size. Because they are smaller, dwarf planets lack the gravitational forces needed to pull in and accumulate all of the material found in their orbits. Each known dwarf planet in our solar system is actually smaller than Earth's Moon!
Dwarf planets in our solar system
As the authority on the naming and classification of celestial objects, the International Astronomical Union officially recognizes five dwarf planets in the solar system:
• Pluto
• Eris
• Ceres
• Makemake
• Haumea
Several dozens more are being considered for the category, and scientists estimate that hundreds or even thousands of dwarf planets may exist in the solar system.
A true colour image of Pluto taken by the New Horizons spacecraft in 2015. (Credit: NASA/JHU APL/SwRI/Alex Parker)
When Pluto was discovered in 1930, it was called the ninth planet in our solar system, but its status as a fully fledged planet came into question in the 1990s. Pluto was officially reclassified as a dwarf planet in 2006.
The best-known dwarf planet, Pluto is also the largest in size and the second largest in mass. Pluto has five moons. The largest, Charon, is over half the size of its host. Pluto's orbit is not circular like those of the other planets and it actually crosses Neptune's orbit, which means that Pluto is sometimes closer to the Sun than Neptune is. It takes Pluto nearly 250 years to complete one trip around the Sun.
Not much was known about Pluto before NASA's New Horizons mission. Launched in 2006, the spacecraft took nearly nine years to reach its target. The mission revealed that Pluto's surface features plains and mountains made of nitrogen ice and water ice.
The dwarf planet Eris and its only moon, Dysnomia.
Located beyond the orbit of Neptune, Eris completes one trip around the Sun every 557 years. It is slightly smaller than Pluto but actually contains over 25% more matter. The discovery of this denser dwarf planet in 2005 may have been the turning point that forced astronomers to reconsider Pluto's classification as a planet. To illustrate this disruption, Eris was named after the Greek goddess of discord. Since Eris is so far away, no surface details can be seen with current instruments, but astronomers have detected the presence of methane ice and believe Eris's surface is similar to that of Pluto.
an aste 940 km (580 mi) in diameter, it is the only asteroid large enough for its collective gravity to pull it into an spheroid. This makes Ceres the only dwarf planet inside Neptune's orbit.
Ceres's small size means that even at its brightest, it is too dim to be seen by the naked eye, except under extremely dark skies. Its apparent magnitude ranges from 6.7 to 9.3, peaking at opposition, when closest to Earth, once during its 15- to 16-month synodic period. Its surface features are barely visible even with the most powerful telescopes, and little was known of them until the robotic NASA spacecraft Dawn entered orbit around Ceres on 6 March 2015.
Dawn found Ceres's surface to be a mixture of water ice and hydrated minerals such as carbonates and clay. Gravity data suggest Ceres to be partially differentiated into a muddy (ice-rock) mantle/core and a less-dense but stronger crust that is at most 30% ice by volume. Despite this, Ceres's small size means that any internal ocean of liquid water it may have possessed has likely frozen by now. Brines still flow through the outer mantle and reach the surface, allowing cryovolcanoes such as Ahuna Mons to form at the rate of about one every 50 million years. These brines provide a potential habitat for microbial life. In January 2014, emissions of water vapor were detected around Ceres, creating a tenuous, transient atmosphere known as an exosphere. This was unexpected because large bodies in the asteroid belt typically do not emit vapor, a hallmark of comets. This makes Ceres the closest known cryovolcanic body to the Sun.
Makemake (minor-planet designation 136472 Makemake) is a dwarf planet and perhaps the second-largest Kuiper belt object in the classical population,with a diameter approximately two-thirds that of Pluto. Makemake has one known satellite. Its extremely low average temperature, about 40 K (-230 °C), means its surface is covered with methane, ethane, and possibly nitrogen ices.
Makemake was discovered on March 31, 2005, by a team led by Michael E. Brown, and announced on July 29, 2005. Initially, it was known as 2005 FY9 and later given the minor-planet number 136472. In July 2008, it was named after Makemake, the creator god of the Rapa Nui people of Easter Island, under the expectation by the International Astronomical Union (IAU) that it would prove to be a dwarf planet.
Haumea (minor-planet designation 136108 Haumea) is a dwarf planet located beyond Neptune's orbit. It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory in the United States and disputably also in 2005 by a team headed by José Luis Ortiz Moreno at the Sierra Nevada Observatory in Spain, though the latter claim has been contested. On September 17, 2008, it was named after Haumea, the Hawaiian goddess of childbirth, under the expectation by the International Astronomical Union (IAU) that it would prove to be a dwarf planet. Nominal estimates make it the third-largest known trans-Neptunian object, after Eris and Pluto, though the uncertainty in best-fit modeling slightly overlaps with the larger size estimates for Makemake.
Haumea's mass is about one-third that of Pluto, and 1/1400 that of Earth. Although its shape has not been directly observed, calculations from its light curve are consistent with it being a Jacobi ellipsoid (the shape it would be if it were a dwarf planet), with its major axis twice as long as its minor. In October 2017, astronomers announced the discovery of a ring system around Haumea, representing the first ring system discovered for a trans-Neptunian object. Haumea's gravity was until recently thought to be sufficient for it to have relaxed into hydrostatic equilibrium, though that is now unclear. Haumea's elongated shape together with its rapid rotation, rings, and high albedo (from a surface of crystalline water ice), are thought to be the consequences of a giant collision, which left Haumea the largest member of a collisional family that includes several large trans-Neptunian objects and Haumea's two known moons, Hi'iaka and Namaka.
Alpha Centauri is the nearest solar system to us located at about 4.37 light years from the sun. It is a triple star system, consisting of
three stars: Centauri A (officially Rigil Kentaurus), Centauri B (officially Toliman), and Centauri C (officially Proxima Centauri). Proxima
Centauri has two planets: Proxima b, an Earth-sized exoplanet in the habitable zone discovered in 2016; and Proxima c, a super-Earth 1.5 AU
away, which is possibly surrounded by a huge ring system, discovered in 2019. |
1. A comet is a small body of ice, rock and cosmic dust loosely packed together |
Halley's returns to the inner Solar System have been observed and recorded by astronomers since at least 240 BCE. Clear records of the comet's appearances were made by Chinese, Babylonian, and medieval European chroniclers, but were not recognized as reappearances of the same object at the time. The comet's periodicity was first determined in 1705 by English astronomer Edmond Halley, after whom it is now named. Halley's Comet last appeared in the inner Solar System in 1986 and will next appear in mid-2061 |
In the early 1990s, NASA established a program called Discovery to competitively select proposals for low-cost solar system exploration missions with highly focused science goals. Stardust, the fourth Discovery mission, sent a spacecraft to fly through the cloud of dust that surrounds the nucleus of a comet. For the first time ever, the mission brought cometary material back to Earth. Stardust was the first U.S. mission dedicated solely to a comet and was the first to return extraterrestrial material from outside the orbit of the moon. Stardust's main objective was to capture a sample from a well-preserved comet called Wild-2 (pronounced "Vilt-2"). Launched February 7, 1999, from Cape Canaveral, Florida, on a Delta II rocket, Stardust collected interstellar dust as it flew through the solar system in spring 2000. On January 15, 2001, the spacecraft executed a flyby of Earth. In summer and fall 2002, the spacecraft again collected interstellar dust.
In 1994, over twenty fragments of comet Shoemaker-Levy 9 collided with the planet Jupiter. |
A meteoroid (/ˈmiː.ti.əˌrɔɪd/) is a small rocky or metallic body in outer space.
Meteoroids are significantly smaller than asteroids, and range in size from small grains to one-meter-wide objects. Objects smaller than this are classified as micrometeoroids or space dust. Most are fragments from comets or asteroids, whereas others are collision impact debris ejected from bodies such as the Moon or Mars.
When a meteoroid, comet, or asteroid enters Earth's atmosphere at a speed typically in excess of 20 km/s (72,000 km/h; 45,000 mph), aerodynamic heating of that object produces a streak of light, both from the glowing object and the trail of glowing particles that it leaves in its wake. This phenomenon is called a meteor or "shooting star". Meteors typically become visible when they are about 100 km above sea level. A series of many meteors appearing seconds or minutes apart and appearing to originate from the same fixed point in the sky is called a meteor shower. A meteorite is the remains of a meteoroid that has survived the ablation of its surface material during its passage through the atmosphere as a meteor and has impacted the ground.
An estimated 25 million meteoroids, micrometeoroids and other space debris enter Earth's atmosphere each day, which results in an estimated 15,000 tonnes of that material entering the atmosphere each year.
What Is a Meteorite?
A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a fireball, also known as a shooting star or falling star; astronomers call the brightest examples "bolides". Once it settles on the larger body's surface, the meteor becomes a meteorite. Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater. Meteorites that are recovered after being observed as they transit the atmosphere and impact the Earth are called meteorite falls. All others are known as meteorite finds. As of August 2018, there were about 1,412 witnessed falls that have specimens in the world's collections.As of July 2021, there are more than 65,780 well-documented meteorite finds. Meteorites have traditionally been divided into three broad categories: stony meteorites that are rocks, mainly composed of silicate minerals; iron meteorites that are largely composed of ferronickel; and stony-iron meteorites that contain large amounts of both metallic and rocky material. Modern classification schemes divide meteorites into groups according to their structure, chemical and isotopic composition and mineralogy. Meteorites smaller than 2 mm are classified as micrometeorites. Extraterrestrial meteorites have been found on the Moon and on Mars.
A meteorite is a meteoroid that reaches the Earth’s surface without burning up.
Three Types of Meteorites:
Stony- Rocky material
Metallic- Iron and Nickel
Stony Metallic- Rocky material, iron and nickel
Stony Meteorites
Metallic Meteorite
Stony-Iron Meteorite
Russian Meteorite
Feb. 15, 2013: A meteorite contrail is seen over Chelyabinsk. A meteor streaked across the sky of Russia’s Ural Mountains on Friday morning, causing sharp explosions and reportedly injuring around 1,000 people, including many hurt by broken glass.
What Is Meteorite Crater?
Meteor Crater is a meteorite impact crater about 37 mi (60 km) east of Flagstaff and 18 miles (29 km) west of Winslow in the northern Arizona desert of the United States. The site had several earlier names, and fragments of the meteorite are officially called the Canyon Diablo Meteorite, after the adjacent Cañon Diablo.Because the United States Board on Geographic Names recognizes names of natural features derived from the nearest post office, the feature acquired the name of "Meteor Crater" from the nearby post office named Meteor. Meteor Crater lies at an elevation of 5,640 ft (1,719 m) above sea level. It is about 3,900 ft (1,200 m) in diameter, some 560 ft (170 m) deep, and is surrounded by a rim that rises 148 ft (45 m) above the surrounding plains. The center of the crater is filled with 690–790 ft (210–240 m) of rubble lying above crater bedrock.[1] One of the interesting features of the crater is its squared-off outline, believed to be caused by existing regional jointing (cracks) in the strata at the impact site. Despite historic attempts to make the crater a public landmark, the crater remains privately owned by the Barringer family to the present day through their Barringer Crater Company, which proclaims it to be the "best-preserved meteorite crater on Earth".Since the crater is privately owned, it is not protected as a national monument, a status that would require federal ownership. It was designated a National Natural Landmark in November 1967. Meteor Crater lies at an elevation of 5,640 ft (1,719 m) above sea level. It is about 3,900 ft (1,200 m) in diameter, some 560 ft (170 m) deep, and is surrounded by a rim that rises 148 ft (45 m) above the surrounding plains. The center of the crater is filled with 690–790 ft (210–240 m) of rubble lying above crater bedrock.[1] One of the interesting features of the crater is its squared-off outline, believed to be caused by existing regional jointing (cracks) in the strata at the impact site. Despite historic attempts to make the crater a public landmark, the crater remains privately owned by the Barringer family to the present day through their Barringer Crater Company, which proclaims it to be the "best-preserved meteorite crater on Earth".Since the crater is privately owned, it is not protected as a national monument, a status that would require federal ownership. It was designated a National Natural Landmark in November 1967.
Impact crater/structure
Diameter - 0.737 miles (1.186 km)
Depth - 560 feet (170 m)
Rise - 148 feet (45 m)
Impactor diameter - 160 feet (50 m)
Age - 50,000 years
Exposed- Yes
Drilled- Yes
Bolide type - Iron meteorite
Location- Coconino County, Arizona
Coordinates - 35°01'41 N 111°01'24 W
A pulsar (from pulsating radio source) is a highly magnetized rotating compact star (usually neutron stars but also white dwarfs) that emits beams of electromagnetic radiation out of its magnetic poles.This radiation can be observed only when a beam of emission is pointing toward Earth (similar to the way a lighthouse can be seen only when the light is pointed in the direction of an observer), and is responsible for the pulsed appearance of emission. Neutron stars are very dense and have short, regular rotational periods. This produces a very precise interval between pulses that ranges from milliseconds to seconds for an individual pulsar. Pulsars are one of the candidates for the source of ultra-high-energy cosmic rays. (See also centrifugal mechanism of acceleration.) The periods of pulsars make them very useful tools for astronomers. Observations of a pulsar in a binary neutron star system were used to indirectly confirm the existence of gravitational radiation. The first extrasolar planets were discovered around a pulsar, PSR B1257+12. In 1983, certain types of pulsars were detected that, at that time, exceeded the accuracy of atomic clocks in keeping time.
Formation of pulsar
The events leading to the formation of a pulsar begin when the core of a massive star is compressed during a supernova, which collapses into a neutron star. The neutron star retains most of its angular momentum, and since it has only a tiny fraction of its progenitor's radius (and therefore its moment of inertia is sharply reduced), it is formed with very high rotation speed. A beam of radiation is emitted along the magnetic axis of the pulsar, which spins along with the rotation of the neutron star. The magnetic axis of the pulsar determines the direction of the electromagnetic beam, with the magnetic axis not necessarily being the same as its rotational axis. This misalignment causes the beam to be seen once for every rotation of the neutron star, which leads to the "pulsed" nature of its appearance. In rotation-powered pulsars, the beam is the result of the rotational energy of the neutron star, which generates an electrical field from the movement of the very strong magnetic field, resulting in the acceleration of protons and electrons on the star surface and the creation of an electromagnetic beam emanating from the poles of the magnetic field. Observations by NICER of J0030-0451 indicate that both beams originate from hotspots located on the south pole and that there may be more than two such hotspots on that star. This rotation slows down over time as electromagnetic power is emitted. When a pulsar's spin period slows down sufficiently, the radio pulsar mechanism is believed to turn off (the so-called "death line"). This turn-off seems to take place after about 10–100 million years, which means of all the neutron stars born in the 13.6 billion year age of the universe, around 99% no longer pulsate. Though the general picture of pulsars as rapidly rotating neutron stars is widely accepted, Werner Becker of the Max Planck Institute for Extraterrestrial Physics said in 2006, "The theory of how pulsars emit their radiation is still in its infancy, even after nearly forty years of work."
Why do pulsars spin?
The slowest pulsars ever detected spin on the order of once per second, and these are typically called slow pulsars. The fastest known pulsars can spin hundreds of times per second, and are known as fast pulsars or millisecond pulsars (because their spin period is measured in milliseconds).
Pulsars spin because the stars from which they formed also rotate, and the collapse of the stellar material will naturally increase the pulsar's rotation speed. (Bringing mass closer to the center of a spinning object increases its rotation speed, which is why figure skaters can spin faster by pulling their arms in toward their torso.)
Pulsars are the size of small cities, so ramping them up to such high speeds is no small feat. In fact, millisecond pulsars require an additional source of energy to get going to such a high rotation rate.
Scientists think millisecond pulsars must have formed by stealing energy from a companion. The pulsar siphons matter and momentum from its companion, gradually increasing the spin rate of the pulsar. This is bad news for the companion star, which may be completely devoured by the pulsar. This would explain why millisecond pulsars have been discovered with no visible companion nearby. Systems where scientists see a pulsar sucking the life from a star are called black widow stars or redback stars, named after two types of dangerous (life-sucking) spiders.
A quasar (/ˈkweɪzɑːr/; also known as a quasi-stellar object, abbreviated QSO) is an extremely luminous active galactic nucleus (AGN), powered by a supermassive black hole,
with mass ranging from millions to tens of billions of times the mass of the Sun, surrounded by a gaseous accretion disk. As gas in the disk falls towards the black hole,
energy is released in the form of electromagnetic radiation, which can be observed across the electromagnetic spectrum. The radiant energy of quasars is enormous; the most
powerful quasars have luminosities thousands of times greater than a galaxy such as the Milky Way. Usually, quasars are categorized as a subclass of the more general
category of AGN. The redshifts of quasars are of cosmological origin.
The term quasar originated as a contraction of "quasi-stellar [star-like] radio source" – because quasars were first identified during the 1950s as sources of radio-wave
emission of unknown physical origin – and when identified in photographic images at visible wavelengths, they resembled faint, star-like points of light. High-resolution
images of quasars, particularly from the Hubble Space Telescope, have demonstrated that quasars occur in the centers of galaxies, and that some host galaxies are strongly
interacting or merging galaxies. As with other categories of AGN, the observed properties of a quasar depend on many factors, including the mass of the black hole, the
rate of gas accretion, the orientation of the accretion disk relative to the observer, the presence or absence of a jet, and the degree of obscuration by gas and dust within
the host galaxy.
More than a million quasars have been found, with the nearest known being about 600 million light-years away from Earth. The record for the most distant known quasar keeps
changing. In 2017, the quasar ULAS J1342+0928 was detected at redshift z = 7.54. Light observed from this 800 million solar mass quasar was emitted when the universe was only
690 million years old. In 2020, the quasar Pōniuāʻena was detected from a time only 700 million years after the Big Bang, and with an estimated mass of 1.5 billion
times the mass of our Sun. In early 2021, the quasar J0313-1806, with a 1.6 billion solar-mass black hole, was reported at z = 7.64, 670 million years after the Big
Bang. In March 2021, PSO J172.3556+18.7734 was detected and has since been called the most distant known radio-loud quasar discovered.
Quasar discovery surveys have demonstrated that quasar activity was more common in the distant past; the peak epoch was approximately 10 billion years ago. Concentrations
of multiple, gravitationally-attracted quasars are known as large quasar groups and constitute some of the largest known structures in the universe.
Each star in the sky is an enormous glowing ball of gas. Our Sun is a medium-sized star. Stars can live for billions of years. The largest stars have the shortest
span(still billions of years); more massive stars burn hotter and faster than their smaller counterparts(like the sun).
Stars twinkle due to air currents in the atmosphere. The colour of any star depends upon its temperature. They appear to be near each other, but actually they
are apart by distances of billions of kilometres. These distances are measured in terms of a very big unit of distance called light year. Light year is used to
measure distances in the Universe. One light year is the distance travelled by light in one year.
A constellation is a group of stars which seen from Earth, form a pattern. The stars in the sky are divided into 88 constellations.
The brightest constellation is Crux (the Southern Cross). The constellation with the greatest number of visible stars in it is Centaurus (the centaur
with 101 stars). The largest constellation is Hydra (The Water Snake).
Our galaxy, the Milky Way, is typical: it has hundreds of billions of stars, enough gas and dust to make billions more stars, and at least ten times as much dark matter as all the stars and gas put together. And it’s all held together by gravity.
Like more than two-thirds of the known galaxies, the Milky Way has a spiral shape. At the center of the spiral, a lot of energy and, occasionally, vivid flares are being generated. Based on the immense gravity that would be required to explain the movement of stars and the energy expelled, the astronomers conclude that the center of the Milky Way is a supermassive black hole.
Other galaxies have elliptical shapes, and a few have unusual shapes like toothpicks or rings. The Hubble Ultra Deep Field (HUDF) shows this diversity. Hubble observed a tiny patch of sky (one-tenth the diameter of the moon) for one million seconds (11.6 days) and found approximately 10,000 galaxies, of all sizes, shapes, and colors. From the ground, we see very little in this spot, which is in the constellation Fornax.
After the Big Bang, the Universe was composed of radiation and subatomic particles. What happened next is up for debate – did small particles slowly team up and gradually form stars, star clusters, and eventually galaxies? Or did the Universe first organize as immense clumps of matter that later subdivided into galaxies?
The shapes of galaxies are influenced by their neighbors, and, often, galaxies collide. The Milky Way is itself on a collision course with our nearest neighbor, the Andromeda galaxy. Even though it is the same age as the Milky Way, Hubble observations reveal that the stars in Andromeda’s halo are much younger than those in the Milky Way. From this and other evidence, astronomers infer that Andromeda has already smashed into at least one and maybe several other galaxies.
Date | Discovery |
---|---|
February 22, 2021 | Eye in the Sky (NGC4826) |
January 18, 2021 | Colors of the Lost Galaxy (NGC 4535) |
January 14, 2021 | Magnetic Chaos Hidden Within the Whirlpool Galaxy |
January 12, 2021 | NASA Missions Help Investigate an ‘Old Faithful’ Active Galaxy |
January 7, 2021 | Hubble Showcases 6 Galaxy Mergers |
January 7, 2021 | Hubble Showcases 6 Galaxy Mergers |
December 21, 2020 | Faint Remnant Threads (NGC 1947) |
December 7, 2020 | The Stellar Forge (NGC 1792) |
November 18, 2020 | 16-Year-Old Cosmic Mystery Solved, Revealing Stellar Missing Link |
November 9, 2020 | Contorting Giants (LRG-3-817) |
October 26, 2020 | Beauty From Chaos (NGC 34) |
September 22, 2020 | Data Sonification: Sounds from Around the Milky Way |
August 27, 2020 | Hubble Maps a Giant Halo Around the Andromeda Galaxy |
August 25, 2020 | NASA Missions Explore a ‘TIE Fighter’ Active Galaxy |
August 10, 2020 | Ring of Stellar Wildfire (NGC 1614) |
July 13, 2020 | A frEGGs-cellent Discovery (J025027.7+600849) |
June 29, 2020 | Birds of a Feather (NGC 2275) |
June 15, 2020 | A Bright Find (PLCK G045.1+61.1) |
June 1, 2020 | Stellar Snowflakes (NGC 6441) |
May 18, 2020 | Stellar Glitter in a Field of Black (ESO 461-036) |
May 11, 2020 | Bending the Bridge Between Two Galaxy Clusters (Abell 2384) |
April 6, 2020 | Rings Upon Rings (NGC 2273) |
February 20, 2020 | Beyond the Brim, Sombrero Galaxy’s Halo Suggests a Turbulent Past |
February 3, 2020 | Nature’s Grand Design (NGC 5364) |
A supernova, plural: supernovae, or supernovas, abbreviations: SN and SNe) is a powerful and luminous stellar explosion. This transient astronomical event occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is destroyed. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months.
Supernovae are more energetic than novae. In Latin, nova means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. The word supernova was coined by Walter Baade and Fritz Zwicky in 1929.
The most recent directly observed supernova in the Milky Way was Kepler's Supernova in 1604, but the remnants of more recent supernovae have been found. Observations of supernovae in other galaxies suggest they occur in the Milky Way on average about three times every century. These supernovae would almost certainly be observable with modern astronomical telescopes. The most recent naked-eye supernova was SN 1987A, the explosion of a blue supergiant star in the Large Magellanic Cloud, a satellite of the Milky Way.
Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-ignition of nuclear fusion in a degenerate star such as a white dwarf, or the sudden gravitational collapse of a massive star's core. In the first class of events, the object's temperature is raised enough to trigger runaway nuclear fusion, completely disrupting the star. Possible causes are an accumulation of material from a binary companion through accretion, or a stellar merger. In the massive star case, the core of a massive star may undergo collapse, releasing gravitational potential energy as a supernova. While some observed supernovae are more complex than these two simplified theories, the astrophysical mechanics are established and accepted by the astronomical community.
Supernovae can expel several solar masses of material at speeds up to several percent of the speed of light. This drives an expanding shock wave into the surrounding interstellar medium, sweeping up an expanding shell of gas and dust observed as a supernova remnant. Supernovae are a major source of elements in the interstellar medium from oxygen to rubidium. The expanding shock waves of supernovae can trigger the formation of new stars. Supernova remnants might be a major source of cosmic rays. Supernovae might produce gravitational waves, though thus far, gravitational waves have been detected only from the mergers of black holes and neutron.
Early work on what was originally believed to be simply a new category of novae was performed during the 1920s. These were variously called "upper-class Novae", "Hauptnovae", or "giant novae". The name "supernovae" is thought to have been coined by Walter Baade and Fritz Zwicky in lectures at Caltech during 1931. It was used, as "super-Novae", in a journal paper published by Knut Lundmark in 1933, and in a 1934 paper by Baade and Zwicky. By 1938, the hyphen had been lost and the modern name was in use. Because supernovae are relatively rare events within a galaxy, occurring about three times a century in the Milky Way, obtaining a good sample of supernovae to study requires regular monitoring of many galaxies.
Supernovae in other galaxies cannot be predicted with any meaningful accuracy. Normally, when they are discovered, they are already in progress. To use supernovae as standard candles for measuring distance, observation of their peak luminosity is required. It is therefore important to discover them well before they reach their maximum. Amateur astronomers, who greatly outnumber professional astronomers, have played an important role in finding supernovae, typically by looking at some of the closer galaxies through an optical telescope and comparing them to earlier photographs.
Supernova discoveries are reported to the International Astronomical Union's Central Bureau for Astronomical Telegrams, which sends out a circular with the name it assigns to that supernova. The name is formed from the prefix SN, followed by the year of discovery, suffixed with a one or two-letter designation. The first 26 supernovae of the year are designated with a capital letter from A to Z. Afterward pairs of lower-case letters are used: aa, ab, and so on. Hence, for example, SN 2003C designates the third supernova reported in the year 2003. The last supernova of 2005, SN 2005nc, was the 367th (14 × 26 + 3 = 367). The suffix "Nc" acts as a bijective base-26 encoding, with a = 1, b = 2, c = 3, ... z = 26. Since 2000, professional and amateur astronomers have been finding several hundred supernovae each year (572 in 2007, 261 in 2008, 390 in 2009; 231 in 2013).
Historical supernovae are known simply by the year they occurred: SN 185, SN 1006, SN 1054, SN 1572 (called Tycho's Nova) and SN 1604 (Kepler's Star). Since 1885 the additional letter notation has been used, even if there was only one supernova discovered that year (e.g. SN 1885A, SN 1907A, etc.)—this last happened with SN 1947A. SN, for Supernova, is a standard prefix. Until 1987, two-letter designations were rarely needed; since 1988, however, they have been needed every year. Since 2016, the increasing number of discoveries has regularly led to the additional use of three-digit designations.
A nebula (Latin for 'cloud' or 'fog'; pl. nebulae, nebulæ or nebulas) is a distinct body of interstellar clouds (which can consist of cosmic dust, hydrogen, helium, molecular clouds; possibly as ionized gases). Originally, the term was used to describe any diffused astronomical object, including galaxies beyond the Milky Way. The Andromeda Galaxy, for instance, was once referred to as the Andromeda Nebula (and spiral galaxies in general as "spiral nebulae") before the true nature of galaxies was confirmed in the early 20th century by Vesto Slipher, Edwin Hubble and others. Edwin Hubble discovered that most nebulae are associated with stars and illuminated by starlight. He also helped categorize nebulae based on the type of light spectra they produced.
Most nebulae are of vast size; some are hundreds of light-years in diameter. A nebula that is visible to the human eye from Earth would appear larger, but no brighter, from close by.The Orion Nebula, the brightest nebula in the sky and occupying an area twice the angular diameter of the full Moon, can be viewed with the naked eye but was missed by early astronomers.Although denser than the space surrounding them, most nebulae are far less dense than any vacuum created on Earth – a nebular cloud the size of the Earth would have a total mass of only a few kilograms. Many nebulae are visible due to fluorescence caused by embedded hot stars, while others are so diffused that they can be detected only with long exposures and special filters. Some nebulae are variably illuminated by T Tauri variable stars. Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions, the formations of gas, dust, and other materials "clump" together to form denser regions, which attract further matter, and eventually will become dense enough to form stars. The remaining material is then believed to form planets and other planetary system objects.
Step outside on a clear night, and you can be sure of something our ancestors could only imagine: Every star you see likely plays host to at least one planet.
The worlds orbiting other stars are called “exoplanets,” and they come in a wide variety of sizes, from gas giants larger than Jupiter to small, rocky planets about as big around as Earth or Mars. They can be hot enough to boil metal or locked in deep freeze. They can orbit their stars so tightly that a “year” lasts only a few days; they can orbit two suns at once. Some exoplanets are sunless rogues, wandering through the galaxy in permanent darkness.
That galaxy, the Milky Way, is the thick stream of stars that cuts across the sky on the darkest, clearest nights. Its spiraling expanse probably contains about 400 billion stars, our Sun among them. And if each of those stars has not just one planet, but, like ours, a whole system of them, then the number of planets in the galaxy is truly astronomical: We’re already heading into the trillions.
We humans have been speculating about such possibilities for thousands of years, but ours is the first generation to know, with certainty, that exoplanets are really out there. In fact, way out there. Our nearest neighboring star, Proxima Centauri, was recently found to possess at least one planet – probably a rocky one. It’s 4.5 light-years away – more than 25 trillion miles (40 trillion kilometers). The bulk of exoplanets found so far are hundreds or thousands of light-years away.
The bad news: As yet we have no way to reach them, and won’t be leaving footprints on them anytime soon. The good news: We can look in on them, take their temperatures, taste their atmospheres and, perhaps one day soon, detect signs of life that might be hidden in pixels of light captured from these dim, distant worlds.
The first exoplanet to burst upon the world stage was 51 Pegasi b, a “hot Jupiter” 50 light-years away that is locked in a four-day orbit around its star. The watershed year was 1995. All of a sudden, exoplanets were a thing.
But a few hints had already emerged. A planet now known as Tadmor was detected in 1988, though the discovery was withdrawn in 1992. Ten years later, more and better data showed definitively that it was really there after all.
And a system of three “pulsar planets” also had been detected, beginning in 1992. These planets orbit a pulsar some 2,300 light-years away. Pulsars are the high-density, rapidly spinning corpses of dead stars, raking any planets in orbit around them with searing lances of radiation.
Now we live in a universe of exoplanets. The count of confirmed planets is 3,700, and rising. That’s from only a small sampling of the galaxy as a whole. The count could rise to the tens of thousands within a decade, as we increase the number, and observing power, of robotic telescopes lofted into space.
We’re standing on a precipice of scientific history. The era of early exploration, and the first confirmed exoplanet detections, is giving way to the next phase: sharper and more sophisticated telescopes, in space and on the ground. They will go broad but also drill down. Some will be tasked with taking an ever more precise population census of these far-off worlds, nailing down their many sizes and types. Others will make a closer inspection of individual planets, their atmospheres, and their potential to harbor some form of life.
Direct imaging of exoplanets – that is, actual pictures – will play an increasingly larger role, though we’ve arrived at our present state of knowledge mostly through indirect means. The two main methods rely on wobbles and shadows. The “wobble” method, called radial velocity, watches for the telltale jitters of stars as they are pulled back and forth by the gravitational tugs of an orbiting planet. The size of the wobble reveals the “weight,” or mass, of the planet
This method produced the very first confirmed exoplanet detections, including 51 Peg in 1995, discovered by astronomers Michel Mayor and Didier Queloz. Ground telescopes using the radial velocity method have discovered nearly 700 planets so far.
But the vast majority of exoplanets have been found by searching for shadows: the incredibly tiny dip in the light from a star when a planet crosses its face. Astronomers call this crossing a “transit.”
The size of the dip in starlight reveals how big around the transiting planet is. Unsurprisingly, this search for planetary shadows is known as the transit method.
NASA’s Kepler space telescope, launched in 2009, has found nearly 2,700 confirmed exoplanets this way. Now in its “K2” mission, Kepler is still discovering new planets, though its fuel is expected to run out soon.
Each method has its pluses and minuses. Wobble detections provide the mass of the planet, but give no information about the planet’s girth, or diameter. Transit detections reveal the diameter but not the mass.
But when multiple methods are used together, we can learn the vital statistics of whole planetary systems – without ever directly imaging the planets themselves. The best example so far is the TRAPPIST-1 system about 40 light-years away, where seven roughly Earth-sized planets orbit a small, red star.
The TRAPPIST-1 planets have been examined with ground and space telescopes. The space-based studies revealed not only their diameters, but the subtle gravitational influence these seven closely packed planets have upon each other; from this, scientists determined each planet’s mass.
So now we know their masses and their diameters. We also know how much of the energy radiated by their star strikes these planets’ surfaces, allowing scientists to estimate their temperatures. We can even make reasonable estimates of the light level, and guess at the color of the sky, if you were standing on one of them. And while much remains unknown about these seven worlds, including whether they possess atmospheres or oceans, ice sheets or glaciers, it’s become the best-known solar system apart from our own.
The next generation of space telescopes is upon us. First up is the launch of TESS, the Transiting Exoplanet Survey Satellite. This extraordinary instrument will take a nearly full-sky survey of the closer, brighter stars to look for transiting planets. Kepler, the past master of transits, will be passing the torch of discovery to TESS.
TESS, in turn, will reveal the best candidates for a closer look with the James Webb Space Telescope, currently schedule to launch in 2020. The Webb telescope, deploying a giant, segmented, light-collecting mirror that will ride on a shingle-like platform, is designed to capture light directly from the planets themselves. The light then can be split into a multi-colored spectrum, a kind of bar code showing which gases are present in the planet’s atmosphere. Webb’s targets might include “super Earths,” or planets larger than Earth but smaller than Neptune – some that could be rocky planets like super-sized versions of our own.
Little is known about these big planets, including whether some might be suitable for life. If we’re very lucky, perhaps one of them will show signs of oxygen, carbon dioxide and methane in its atmosphere. Such a mix of gases would remind us strongly of our own atmosphere, possibly indicating the presence of life.
But hunting for Earth-like atmospheres on Earth-sized exoplanets will probably have to wait for a future generation of even more powerful space probes in the 2020s or 2030s.
Thanks to the Kepler telescope’s statistical survey, we know the stars above are rich with planetary companions. And as we stare up at the night sky, we can be sure not only of a vast multitude of exoplanet neighbors, but of something else: The adventure is just beginning.
In the early 1990s, one thing was fairly certain about the expansion of the universe. It might have enough energy density to stop its expansion and recollapse, it might have so little energy density that it would never stop expanding, but gravity was certain to slow the expansion as time went on. Granted, the slowing had not been observed, but, theoretically, the universe had to slow. The universe is full of matter and the attractive force of gravity pulls all matter together. Then came 1998 and the Hubble Space Telescope (HST) observations of very distant supernovae that showed that, a long time ago, the universe was actually expanding more slowly than it is today. So the expansion of the universe has not been slowing due to gravity, as everyone thought, it has been accelerating. No one expected this, no one knew how to explain it. But something was causing it.
Eventually theorists came up with three sorts of explanations. Maybe it was a result of a long-discarded version of Einstein’s theory of gravity, one that contained what was called a “cosmological constant.” Maybe there was some strange kind of energy-fluid that filled space. Maybe there is something wrong with Einstein’s theory of gravity and a new theory could include some kind of field that creates this cosmic acceleration. Theorists still don’t know what the correct explanation is, but they have given the solution a name. It is called dark energy.
More is unknown than is known. We know how much dark energy there is because we know how it affects the universe’s expansion. Other than that, it is a complete mystery. But it is an important mystery. It turns out that roughly 68% of the universe is dark energy. Dark matter makes up about 27%. The rest – everything on Earth, everything ever observed with all of our instruments, all normal matter – adds up to less than 5% of the universe. Come to think of it, maybe it shouldn’t be called “normal” matter at all, since it is such a small fraction of the universe.
One explanation for dark energy is that it is a property of space. Albert Einstein was the first person to realize that empty space is not nothing. Space has amazing properties, many of which are just beginning to be understood. The first property that Einstein discovered is that it is possible for more space to come into existence. Then one version of Einstein’s gravity theory, the version that contains a cosmological constant, makes a second prediction: “empty space” can possess its own energy. Because this energy is a property of space itself, it would not be diluted as space expands. As more space comes into existence, more of this energy-of-space would appear. As a result, this form of energy would cause the universe to expand faster and faster. Unfortunately, no one understands why the cosmological constant should even be there, much less why it would have exactly the right value to cause the observed acceleration of the universe.
Another explanation for how space acquires energy comes from the quantum theory of matter. In this theory, “empty space” is actually full of temporary (“virtual”) particles that continually form and then disappear. But when physicists tried to calculate how much energy this would give empty space, the answer came out wrong – wrong by a lot. The number came out 10120 times too big. That’s a 1 with 120 zeros after it. It’s hard to get an answer that bad. So the mystery continues.
Another explanation for dark energy is that it is a new kind of dynamical energy fluid or field, something that fills all of space but something whose effect on the expansion of the universe is the opposite of that of matter and normal energy. Some theorists have named this “quintessence,” after the fifth element of the Greek philosophers. But, if quintessence is the answer, we still don’t know what it is like, what it interacts with, or why it exists. So the mystery continues.
A last possibility is that Einstein’s theory of gravity is not correct. That would not only affect the expansion of the universe, but it would also affect the way that normal matter in galaxies and clusters of galaxies behaved. This fact would provide a way to decide if the solution to the dark energy problem is a new gravity theory or not: we could observe how galaxies come together in clusters. But if it does turn out that a new theory of gravity is needed, what kind of theory would it be? How could it correctly describe the motion of the bodies in the Solar System, as Einstein’s theory is known to do, and still give us the different prediction for the universe that we need? There are candidate theories, but none are compelling. So the mystery continues.
The thing that is needed to decide between dark energy possibilities – a property of space, a new dynamic fluid, or a new theory of gravity – is more data, better data.
By fitting a theoretical model of the composition of the universe to the combined set of cosmological observations, scientists have come up with the composition that we described above, ~68% dark energy, ~27% dark matter, ~5% normal matter.
We are much more certain what dark matter is not than we are what it is. First, it is dark, meaning that it is not in the form of stars and planets that we see. Observations show that there is far too little visible matter in the universe to make up the 27% required by the observations. Second, it is not in the form of dark clouds of normal matter, matter made up of particles called baryons. We know this because we would be able to detect baryonic clouds by their absorption of radiation passing through them. Third, dark matter is not antimatter, because we do not see the unique gamma rays that are produced when antimatter annihilates with matter. Finally, we can rule out large galaxy-sized black holes on the basis of how many gravitational lenses we see. High concentrations of matter bend light passing near them from objects further away, but we do not see enough lensing events to suggest that such objects to make up the required 25% dark matter contribution.
The cosmic microwave background (CMB) is thought to be leftover radiation from the Big Bang, or the time when the universe began. As the theory goes, when the universe was born it underwent a rapid inflation and expansion. (The universe is still expanding today, and the expansion rate appears different depending on where you look). The CMB represents the heat left over from the Big Bang.
You can’t see the CMB with your naked eye, but it is everywhere in the universe. It is invisible to humans because it is so cold, just 2.725 degrees above absolute zero (minus 459.67 degrees Fahrenheit, or minus 273.15 degrees Celsius.) This means its radiation is most visible in the microwave part of the electromagnetic spectrum.
The universe began 13.8 billion years ago, and the CMB dates back to about 400,000 years after the Big Bang. That’s because in the early stages of the universe, when it was just one-hundred-millionth the size it is today, its temperature was extreme: 273 million degrees above absolute zero, according to NASA. Any atoms present at that time were quickly broken apart into small particles (protons and electrons). The radiation from the CMB in photons (particles representing quantums of light, or other radiation) was scattered off the electrons. “Thus, photons wandered through the early universe, just as optical light wanders through a dense fog,” NASA wrote.
About 380,000 years after the Big Bang, the universe was cool enough that hydrogen could form. Because the CMB photons are barely affected by hitting hydrogen, the photons travel in straight lines. Cosmologists refer to a “surface of last scattering” when the CMB photons last hit matter; after that, the universe was too big. So when we map the CMB, we are looking back in time to 380,000 years after the Big Bang, just after the universe was opaque to radiation.
American cosmologist Ralph Apher first predicted the CMB in 1948, when he was doing work with Robert Herman and George Gamow, according to NASA. The team was doing research related to Big Bang nucleosynthesis, or the production of elements in the universe besides the lightest isotope (type) of hydrogen. This type of hydrogen was created very early in the universe’s history.
But the CMB was first found by accident. In 1965, two researchers with Bell Telephone Laboratories (Arno Penzias and Robert Wilson) were creating a radio receiver, and were puzzled by the noise it was picking up. They soon realized the noise came uniformly from all over the sky. At the same time, a team at Princeton University (led by Robert Dicke) was trying to find the CMB. Dicke’s team got wind of the Bell experiment and realized the CMB had been found.
Both teams quickly published papers in the Astrophysical Journal in 1965, with Penzias and Wilson talking about what they saw, and Dicke’s team explaining what it means in the context of the universe. (Later, Penzias and Wilson both received the 1978 Nobel Prize in physics).
The CMB is useful to scientists because it helps us learn how the early universe was formed. It is at a uniform temperature with only small fluctuations visible with precise telescopes. “By studying these fluctuations, cosmologists can learn about the origin of galaxies and large-scale structures of galaxies and they can measure the basic parameters of the Big Bang theory,” NASA wrote.
While portions of the CMB were mapped in the ensuing decades after its discovery, the first space based full-sky map came from NASA’s Cosmic Background Explorer (COBE) mission, which launched in 1989 and ceased science operations in 1993. This “baby picture” of the universe, as NASA calls it, confirmed Big Bang theory predictions and also showed hints of cosmic structure that were not seen before. In 2006, the Nobel Prize in physics was awarded to COBE scientists John Mather at the NASA Goddard Space Flight Center, and George Smoot at the University of California, Berkeley.
A more detailed map came in 2003 courtesy of the Wilkinson Microwave Anisotropy Probe (WMAP), which launched in June 2001 and stopped collecting science data in 2010. The first picture pegged the universe’s age at 13.7 billion years (a measurement since refined to 13.8 billion years) and also revealed a surprise: the oldest stars started shining about 200 million years after the Big Bang, far earlier than predicted.
Scientists followed up those results by studying the very early inflation stages of the universe (in the trillionth second after formation) and by giving more precise parameters on atom density, the universe’s lumpiness and other properties of the universe shortly after it was formed. They also saw a strange asymmetry in average temperatures in both hemispheres of the sky, and a “cold spot” that was bigger than expected. The WMAP team received the 2018 Breakthrough Prize in Fundamental Physics for their work.
In 2013, data from the European Space Agency’s Planck space telescope was released, showing the highest precision picture of the CMB yet. Scientists uncovered another mystery with this information: Fluctuations in the CMB at large angular scales did not match predictions. Planck also confirmed what WMAP saw in terms of the asymmetry and the cold spot. Planck’s final data release in 2018 (the mission operated between 2009 and 2013) showed more proof that dark matter and dark energy — mysterious forces that are likely behind the acceleration of the universe — do seem to exist.
Other research efforts have attempted to look at different aspects of the CMB. One is determining types of polarization called E-modes (discovered by the Antarctica-based Degree Angular Scale Interferometer in 2002) and B-modes. B-modes can be produced from gravitational lensing of E-modes (this lensing was first seen by the South Pole Telescope in 2013) and gravitational waves (which were first observed in 2016 using the Advanced Laser Interferometer Gravitational Wave Observatory, or LIGO). In 2014, the Antarctic-based BICEP2 instrument was said to have found gravitational wave B-modes, but further observation (including work from Planck) showed these results were due to cosmic dust.
As of mid-2018, scientists are still looking for the signal that showed a brief period of fast universe expansion shortly after the Big Bang. At that time, the universe was getting bigger at a rate faster than the speed of light. If this happened, researchers suspect this should be visible in the CMB through a form of polarization. A study that year suggested that a glow from nanodiamonds creates a faint, but discernible, light that interferes with cosmic observations. Now that this glow is accounted for, future investigations could remove it to better look for the faint polarization in the CMB, study authors said at the time.
Humans have always been curios to explore. In around the 1600's, the world thought it was a very hard job to sail across the sea. But nowadys, that is very little as the aviation industry has helped humans to travel from point A to Point B a lot faster than having to sail there in a few days even years somtimes. Now people travel to space, Even if your not an Astronaut! So let's talk about the start of space travel. Space Travel was first introduced by Russia's ROSKOSMOS, who sent the first man Yuri Gagarin into space. There was a USA's and Russia's ROSKOSMOS rivalry to see who lands on the moon first which USA's NASA won by sending Neil Armstrong, Michael Collins and Buzz Aldrin but only Neil Armstrong and Buzz Aldrin stepped on the moon. There was even sending satellites to space which Russia's ROSKOSMOS won again by sending the Sputnik satellite. Next was sending satellites to Mars many countries succeded but nobody was able to do it on their first try except India's ISRO whos sent their satellite to Mars on the PSLV(Polar Satellite Launch Vehicle). Astronauts meaning 'Space Sailor' also live in space in the ISS (International Space Station). There are even telescopes in space. There are many private companies like SpaceX, Virgin Galactic, Firefly etc. Space travel is also becoming famous SpaceX had lauched the Inspiration4 mission with only travellers, Blue Origin lauched their First Human Flight with a former astronaut and 3 travellers. Both the missions were autmated but were trained just in case.
The International Space Station (ISS) is a modular space station (habitable artificial satellite) in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). The ownership and use of the space station is established by intergovernmental treaties and agreements.[9] The station serves as a microgravity and space environment research laboratory in which scientific research is conducted in astrobiology, astronomy, meteorology, physics, and other fields. The ISS is suited for testing the spacecraft systems and equipment required for possible future long-duration missions to the Moon and Mars.
The ISS programme evolved from the Space Station Freedom, an American proposal which was conceived in 1984 to construct a permanently manned Earth-orbiting station, and the contemporaneous Soviet/Russian Mir-2 proposal from 1976 with similar aims. The ISS is the ninth space station to be inhabited by crews, following the Soviet and later Russian Salyut, Almaz, and Mir stations and the American Skylab. It is the largest artificial object in space and the largest satellite in low Earth orbit, regularly visible to the naked eye from Earth's surface. It maintains an orbit with an average altitude of 400 kilometres (250 mi) by means of reboost manoeuvres using the engines of the Zvezda Service Module or visiting spacecraft. The ISS circles the Earth in roughly 93 minutes, completing 15.5 orbits per day.
The station is divided into two sections: the Russian Orbital Segment (ROS) is operated by Russia, while the United States Orbital Segment (USOS) is run by the United States as well as many other nations. Roscosmos has endorsed the continued operation of ROS through 2024, having previously proposed using elements of the segment to construct a new Russian space station called OPSEK. The first ISS component was launched in 1998, and the first long-term residents arrived on 2 November 2000 after being launched from the Baikonur Cosmodrome on 31 October 2000. The station has since been continuously occupied for 20 years and 330 days, the longest continuous human presence in low Earth orbit, having surpassed the previous record of 9 years and 357 days held by the Mir space station. The latest major pressurised module, Nauka, was fitted in 2021, a little over ten years after the previous major addition, Leonardo in 2011. Development and assembly of the station continues, with an experimental inflatable space habitat added in 2016, and several major new Russian elements scheduled for launch starting in 2021. In December 2018, the station's operation authorization was extended to 2030, with funding secured until 2025.[23] There have been calls to privatize ISS operations after that point to pursue future Moon and Mars missions, with former NASA Administrator Jim Bridenstine saying "given our current budget constraints, if we want to go to the moon and we want to go to Mars, we need to commercialize low Earth orbit and go on to the next step."
The ISS consists of pressurised habitation modules, structural trusses, photovoltaic solar arrays, thermal radiators, docking ports, experiment bays and robotic arms. Major ISS modules have been launched by Russian Proton and Soyuz rockets and US Space Shuttles. The station is serviced by a variety of visiting spacecraft: the Russian Soyuz and Progress, the SpaceX Dragon 2, and the Northrop Grumman Space Systems Cygnus, and formerly the European Automated Transfer Vehicle (ATV), the Japanese H-II Transfer Vehicle, and SpaceX Dragon 1. The Dragon spacecraft allows the return of pressurised cargo to Earth, which is used, for example, to repatriate scientific experiments for further analysis. As of August 2021, 244 astronauts, cosmonauts, and space tourists from 19 different nations have visited the space station, many of them multiple times; this includes 153 Americans, 50 Russians, 9 Japanese, 8 Canadians, 5 Italians and 1 Brazilian.
India decided to go to space when Indian National Committee for Space Research (INCOSPAR) was set up by the Government of India in 1962. With the visionary Dr Vikram Sarabhai at its helm, INCOSPAR set up the Thumba Equatorial Rocket Launching Station (TERLS) in Thiruvananthapuram for upper atmospheric research.
Indian Space Research Organisation, formed in 1969, superseded the erstwhile INCOSPAR. Vikram Sarabhai, having identified the role and importance of space technology in a Nation's development, provided ISRO the necessary direction to function as an agent of development. ISRO then embarked on its mission to provide the Nation space based services and to develop the technologies to achieve the same independently.
Throughout the years, ISRO has upheld its mission of bringing space to the service of the common man, to the service of the Nation. In the process, it has become one of the six largest space agencies in the world. ISRO maintains one of the largest fleet of communication satellites (INSAT) and remote sensing (IRS) satellites, that cater to the ever growing demand for fast and reliable communication and earth observation respectively. ISRO develops and delivers application specific satellite products and tools to the Nation: broadcasts, communications, weather forecasts, disaster management tools, Geographic Information Systems, cartography, navigation, telemedicine, dedicated distance education satellites being some of them.
To achieve complete self reliance in terms of these applications, it was essential to develop cost efficient and reliable launch systems, which took shape in the form of the Polar Satellite Launch Vehicle (PSLV). The famed PSLV went on to become a favoured carrier for satellites of various countries due to its reliability and cost efficiency, promoting unprecedented international collaboration. The Geosynchronous Satellite Launch Vehicle (GSLV) was developed keeping in mind the heavier and more demanding Geosynchronous communication satellites.
Apart from technological capability, ISRO has also contributed to science and science education in the country. Various dedicated research centres and autonomous institutions for remote sensing, astronomy and astrophysics, atmospheric sciences and space sciences in general function under the aegis of Department of Space. ISRO's own Lunar and interplanetary missions along with other scientific projects encourage and promote science education, apart from providing valuable data to the scientific community which in turn enriches science.
Future readiness is the key to maintaining an edge in technology and ISRO endeavours to optimise and enhance its technologies as the needs and ambitions of the country evolve. Thus, ISRO is moving forward with the development of heavy lift launchers, human spaceflight projects, reusable launch vehicles, semi-cryogenic engines, single and two stage to orbit (SSTO and TSTO) vehicles, development and use of composite materials for space applications etc.
The Indian National Committee for Space Research (INCOSPAR) was established by Jawaharlal Nehru in 1962 under the Department of Atomic Energy (DAE). Eminent scientist Dr Vikram Sarabhai had a big role in this development. He understood the need for space research and was convinced of the role it can play in helping a nation develop. INCOSPAR set up the Thumba Equatorial Rocket Launching Station (TERLS) at Thumba, near Thiruvananthapuram at India’s southern tip. TERLS is a spaceport used to launch rockets. The INCOSPAR became ISRO in 1969.
The Department of Space was created in 1972 and ISRO became a part of it and remains so till date. The Space Department reports directly to the Prime Minister of the country. During 1975-76, Satellite Instructional Television Experiment (SITE) was conducted. It was hailed as ‘the largest sociological experiment in the world’. It was followed by the ‘Kheda Communications Project (KCP)’, which worked as a field laboratory for need-based and locale-specific program transmission in the state of Gujarat State. During this phase, the first Indian spacecraft ‘Aryabhata’ was developed and was launched using a Soviet Launcher.
Another major landmark was the development of the first launch vehicle SLV-3 with a capability to place 40 kg in Low Earth Orbit (LEO), which had its first successful flight in 1980. ’80s was the experimental phase wherein, Bhaskara-I & II missions were pioneering steps in the remote sensing area whereas ‘Ariane Passenger Payload Experiment (APPLE)’ became the forerunner for the future communication satellite systems. Antrix Corporation Limited (ACL) is a Marketing arm of ISRO for promotion and commercial exploitation of space products, technical consultancy services and transfer of technologies developed by ISRO.
ISRO has many facilities each dedicated to a specialized field of study in space. A few of them are as follows:
Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram – The space research activities were initiated in India under Dr. Vikram Sarabhai, the founding father of the Indian space program, during 1960s.
The first Indian-made sounding rocket was the RH-75 (Rohini-75). It was launched from TERLS in 1967. It weighed just 32 kg. Series of Rohini Sounding Rockets were developed by ISRO for atmospheric and meteorological studies. ISRO built its first satellite in 1975 and named it Aryabhata. This was launched by the Soviet Union.
The first Indian-built launch vehicle was SLV-3 and it was used to launch the Rohini satellite in 1980.
ISRO launched its first INSAT satellite in 1982. It was a communication satellite. It was named as INSAT-1A, which failed in orbit. The next communication satellite INSAT-1B was launched in 1983.
Established in 1983 with commissioning of INSAT-1B, the Indian National Satellite (INSAT) system is one of the largest domestic communication satellite systems in the Asia-Pacific region with nine operational communication satellites placed in Geostationary orbit. Details regarding INSAT – 1B are available on the linked page. The INSAT system provides services to telecommunications, television broadcasting, satellite newsgathering, societal applications, weather forecasting, disaster warning and Search and Rescue operations. ISRO also launched the first IRS (remote-sensing satellite) in 1988.
ISRO has developed three types of launch vehicles (or rockets) namely, the PSLV (Polar Satellite Launch Vehicle), the GSLV (Geosynchronous Satellite Launch Vehicle) and Geosynchronous Satellite Launch Vehicle Mark III (GSLV Mark III or LVM). Further details on GSLV MK III are available on the link provided here. ISRO launched its first lunar mission Chandrayaan I in 2008.
It also launched the Mars Orbiter Mission (MOM) or the Mangalyaan in 2014. With this, India became the first country to achieve success in putting a satellite in the Mars orbit in its maiden attempt and the fourth space agency and the first space Asian agency to do so. Read the details on Mangalyaan Mission here. ISRO has launched many small satellites mainly for experimental purposes such as INS-1C, Aryabhatta, APPLE, Rohini Technology Payload, YOUTHSAT, etc. The experiment includes Remote Sensing, Atmospheric Studies, Payload Development, Orbit Controls, recovery technology and more. Scramjet (Supersonic Combustion Ramjet) engine – In August 2016, ISRO successfully conducted the Scramjet (Supersonic Combustion Ramjet) engine test. It uses Hydrogen as fuel and Oxygen from the atmospheric air as the oxidizer. ISRO’s Advanced Technology Vehicle (ATV), which is an advanced sounding rocket, was the solid rocket booster used for the test of Scramjet engines at supersonic conditions. This test was the maiden short duration experimental test of ISRO’s Scramjet engine with a hypersonic flight at Mach 6. The new propulsion system will complement ISRO’s reusable launch vehicle that would have a longer flight duration. Read in detail about the Advance Technology Vehicle of ISRO on the given link. In 2017, ISRO created another world record by launching 104 satellites in a single rocket. It launched its heaviest rocket yet, the Geosynchronous Satellite Launch Vehicle-Mark III and placed the GSAT 19 in orbit. India’s Manned Mission to Space also termed as Gaganyaan, this project is part of the government’s ambition to make India a global low-cost provider of services in space. The launch vehicle for this mission will carry heavy payloads into space. For this purpose, GSLV Mk-III is being developed with a cryogenic engine. ISRO has already tested the GSLV Mk-III with experimental crew module (Re-entry & Recovery technology) and Crew Escape System (CES). Detailed information on Gaganyaan Mission is available on the linked page. Also read the List of Indian Satellite From 1975 to 2021 on the given link.
Candidates can go through a few more achievements of ISRO mentioned below –
ISRO has launched many operational remote sensing satellites, starting with IRS-1A in 1988. Detailed information on IRS-1A – the first indigenous remote sensing satelite is available on the linked page. Today, India has one of the largest constellations of remote sensing satellites in operation. The data from these satellites are used for several applications covering agriculture, water resources, urban planning, rural development, mineral prospecting, environment, forestry, ocean resources and disaster management.
Navigation services are necessary to meet the emerging demands of the Civil Aviation requirements and to meet the user requirements of the positioning, navigation and timing based on the independent satellite navigation system. ISRO worked jointly with Airport Authority of India (AAI) in establishing the GPS Aided Geo Augmented Navigation (GAGAN) system to meet the Civil Aviation requirements. Similarly, it established a regional satellite navigation system called the Indian Regional Navigation Satellite System (IRNSS) to meet the user requirements of the positioning, navigation and timing services. Know more on IRNSS-NAVIC on the linked page.
ISRO has influenced educational institutions by its activities like making satellites for communication, remote sensing and astronomy. The launch of Chandrayaan-1 increased the interest of universities and institutions towards making experimental student satellites. Some important Academic Institute Satellite are – Kalamsat-V2, PRATHAM, SATHYABAMASAT, SWAYAM, Jugnu, etc.
ISRO’s vision is stated as “Harness space technology for national development while pursuing space science research and planetary exploration.”
Design and development of launch vehicles and related technologies for providing access to space.
Design and development of satellites and related technologies for earth observation, communication, navigation, meteorology and space science. Indian National Satellite (INSAT) programme for meeting telecommunication, television broadcasting and developmental applications. Indian Remote Sensing Satellite (IRS) programme for management of natural resources and monitoring of environment using space-based imagery.
Space-based Applications for Societal development.Research and Development in space science and planetary exploration.
Stamp depicting SLV-3 D1 carrying RS-D1 satellite to orbit.
NASA stands for National Aeronautics and Space Administration. NASA is a U.S. government agency that is responsible for science and technology related to air and space. The Space Age started in 1957 with the launch of the Soviet satellite Sputnik.
NASA opened for business on Oct. 1, 1958. The agency was created to oversee U.S. space exploration and aeronautics research.
The administrator is in charge of NASA. The NASA administrator is nominated by the president and confirmed by a vote in the Senate.
Many people know something about NASA’s work. But most probably have no idea about how many different things the agency does. Astronauts in orbit conduct scientific research. Satellites help scientists learn more about Earth. Space probes study the solar system and beyond. New developments improve air travel and other aspects of flight. NASA is also beginning a new program to send humans to explore the Moon and Mars. In addition to those major missions, NASA does many other things. The agency shares what it learns so that its information can make life better for people worldwide. For example, companies can use NASA discoveries to create new spinoff products.
NASA helps teachers prepare students who will be the engineers, scientists, astronauts and other NASA workers of the future. They will be the adventurers who will continue exploration of the solar system and universe. NASA has a tradition of investing in programs and activities that inspire students, educators, families and communities in the excitement and discovery of exploration. NASA offers training to help teachers learn new ways to teach science, technology, engineering and mathematics. The agency also involves students in NASA missions to help them get excited about learning.
NASA’s Headquarters is in Washington, D.C. The agency has nine centers, the Jet Propulsion Laboratory and seven test and research facilities located in several states around the country. More than 17,000 people work for NASA. Many more people work with the agency as government contractors. These people are hired by companies that NASA pays to do work. The combined workforce represents a variety of jobs. Astronauts may be the best-known NASA employees, but they only represent a small number of the total workforce. Many NASA workers are scientists and engineers. But people there hold many other jobs, too, from secretaries to writers to lawyers to teachers.
When NASA started, it began a program of human spaceflight. The Mercury, Gemini and Apollo programs helped NASA learn about flying in space and resulted in the first human landing on the Moon in 1969. Currently, NASA has astronauts living and working on the International Space Station.
NASA’s robotic space probes have visited every planet in the solar system and several other celestial bodies. Telescopes have allowed scientists to look at the far reaches of space. Satellites have revealed a wealth of data about Earth, resulting in valuable information such as a better understanding of weather patterns.
NASA has helped develop and test a variety of cutting-edge aircraft. These aircraft include planes that have set new records. Among other benefits, these tests have helped engineers improve air transportation. NASA technology has contributed to many items used in everyday life, from smoke detectors to medical tests.
In 2018, NASA celebrated its 60th anniversary.
The Japan Aerospace Exploration Agency is the Japanese national aerospace and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into orbit, and is involved in many more advanced missions such as asteroid exploration and possible human exploration of the Moon. Its motto is One JAXA and its corporate slogan is Explore to Realize.
Roscosmos, also known as the Roscosmos State Corporation for Space Activities, is the coordinating hub for space activities in Russia. It performs numerous civilian activities (including Earth monitoring and the astronaut program) and coordinates with the Defense Ministry of the Russian Federation for military launches.
Roscosmos used to be known as the Russian Federal Space Agency, which was formed in 1992. The new corporation was formed from merging the agency and United Rocket and Space Corporation, a joint-stock entity meant to bolster the space sector. Russia's involvement in space, however, long predates these events. At the height of the former Soviet Union's space prowess in the 1950s and 1960s, the country racked up several world firsts — including the first human in space.
Roscosmos came to be in a different era, shortly after the breakup of the Soviet Union. The agency poured its scant resources into the International Space Station and to this day remains a major participant in the effort. In 2016, it opened a new launch complex called Vostochny that is intended to eventually take over most of the duties of the Baikonur Cosmodrome, its current primary launch facility in Kazakhstan.
Soviet experience with space threads through much of the past century. Konstantin Tsiolkovsky's pioneering rocketry work extended through the late 19th and early 20th centuries. The Soviets then supplemented that experience with German V2 missile engineers acquired after the end of World War II in 1945. The United States had another group of Germans from the same program.
Under the auspices of International Geophysical Year in 1957-58, the Soviets launched the world's first satellite (Sputnik) on Oct. 4, 1957. Some in the United States worried about the influence of communism in outer space. As Americans scrambled to catch up, the Soviets accomplished many world firsts. Among them were the first man in space (Yuri Gagarin), first woman (Valentina Tereshkova), first lunar flyby (Luna 1) and first three-person crew (Voskhod 1).
The Soviets, however, also had their share of disasters. On Oct. 24, 1960, an R-16 missile detonated at Baikonur and killed an estimated 150 people; the details weren't known by the public, or even the affected families, for many decades. The missions of Soyuz 1 (1967) and Soyuz 11 (1971) both launched from Baikonur and ended with disaster upon landing, which between the two missions killed four astronauts. Another famous example of disaster was the N-1 rocket explosion that detonated on the launch pad on July 3, 1969. While there were no fatalities, it damaged the launch facilities and derailed Soviet plans to send astronauts to the moon.
Subsequently, the Soviets focused on space station technology, most notably in the form of the Salyut and the Mir space station programs. Mir hosted the longest human spaceflight to date: Valeri Polyakov, in 1994. The Soviet expertise in long-duration spaceflight impressed NASA, which decided to partner with the Russians after the Soviet Union fell apart in the early 1990s.
Collaboration with NASA dates back to the 1970s, with the Apollo-Soyuz Test Project of 1975, which saw a Russian Soyuz spacecraft and an American Apollo spacecraft meet in Earth orbit. The astronauts and cosmonauts worked together in space briefly before heading off for their own separate missions.
After the Soviet Union broke apart in 1991, funds reportedly ran thin for the Russian space program. A year later, Roscosmos was formed to coordinate space activities for Russia. The United States was concerned that the fall of the Soviet Union might cause economic havoc in that area of the world. So, NASA offered paid astronaut flights to the Mir space station, with its astronauts receiving technical and language training in Russia before flights. The Shuttle-Mir program (as it was called) flew several American astronauts to Mir between 1995 and 1998. It also laid the groundwork for the International Space Station collaboration; Russian officials eventually elected to focus their resources on the ISS and de-orbit the aging Mir.
As of early 2018, all astronauts leaving for the ISS leave from Baikonur. This situation has persisted since 2011, when NASA retired the aging space shuttle. At the time, the agency expected to restart flights on U.S. soil in 2015, when the Commercial Crew Program's spacecraft were ready. However, funding and development delays now have test flights expected to start no earlier than 2018.
NASA currently buys seats on Russian spacecraft for its astronauts, a practice that was projected to climb to $82 million per person by 2018. For Russia, contributing cargo launches and launch hardware — not to mention other Russian modules on station — allows the country to send numerous cosmonauts into space. Many three-person Soyuz crews that head to the station for long-term stays have multiple Russians on board.
In 2011, Russia started construction on another launch site — Vostochny — which is in Siberia and close to the Chinese border. The long-term aim is to shift most Russian launches to Vostochny, which unlike Baikonur, is on Russian soil. (Baikonur used to be inside the Soviet Union, but Kazakhstan since declared independence and the Russians lease the facility.) While Russia initially planned to have crewed launches start at Vostochny in 2018, there have been few launches at the facility to date. Three satellites were successfully launched in 2016, but after Vostochny's second launch in late 2017, a $45 million satellite was lost.
Roscosmos is a major provider of launch services to other countries. Its Proton rocket line has had a few snags over the years. Three Breeze-M upper stages failed in separate launches across 16 months, prompting a full review in late 2012. Then in 2013, another booster failed 17 seconds after the launch. Satellites were also lost in failure in 2015 and 2015.
In addition to launching satellites for other countries, Roscosmos does numerous satellite missions of its own. Some examples include Earth observation, military satellites, telecommunications, and Glosnass navigation satellites.
In 2013, a fragment of a Chinese satellite (Fengyun 1C) reportedly collided with a small Russian laser-ranging satellite called BLITS (Ball Lens in The Space). The crash knocked BLITS from its original orbit and broke it into at least two fragments.
Russia is now looking ahead to a major Mars mission, ExoMars, which it is doing with the European Space Agency. ExoMars' first leg (the Trace Gas Orbiter) launched successfully in 2016, while a rover was delayed by two years (due to scheduling problems) until an expected launch in 2020. Roscosmos is hoping the mission will break the streak of several failed Mars missions, most recently the Phobos-Grunt failure that occurred in 2012 when the probe could not break free of Earth's orbit.
Media reports have said that Russia is interested in developing a series of robotic moon missions, which would be dubbed Luna-Glob. However, budgetary restraints have reportedly pushed back the first of these missions until at least 2025.
China National Space Administration (CNSA) (Chinese: 国家航天局; pinyin: Guójiā Hángtiān Jú) is the national space agency of China responsible for the national space programand for planning and development of space activities. CNSA and China Aerospace Science and Technology Corporation (CASC) assumed the authority over space development efforts previously held by the Ministry of Aerospace Industry. It is a subordinate agency of the State Administration for Science, Technology and Industry for National Defence (SASTIND), itself a subordinate agency of the Ministry of Industry and Information Technology (MIIT). The headquarter is in Haidian District, Beijing.
Despite its relatively short history, CNSA has pioneered a number of achievements in space for China, including becoming the first space agency to land on the far side of the Moon with Chang'e 4, bringing material back from the Moon with Chang'e 5, and being the second agency who successfully landed a rover on Mars with Tianwen-1.
The human spaceflight program of China, namely China Manned Space Program, is not administered by CNSA, but China Manned Space Agency (CMSA).
The Canadian Space Agency (CSA; French: Agence spatiale canadienne, ASC) is the national space agency of Canada, established in 1990 by the Canadian Space Agency Act. The agency is responsible to the minister of innovation, science, and economic development.
The president is Lisa Campbell, who took the position on September 3, 2020. The CSA's headquarters are located at the John H. Chapman Space Centre in Longueuil, Quebec. The agency also has offices in Ottawa, Ontario, and small liaison offices in Houston; Washington, D.C.; and Paris.
Presidents
The United Arab Emirates Space Agency (UAESA) (Arabic: وكالة الإمارات للفضاء translit: wikālat al-Imārāt l-lifaḍā') is the space agency of the United Arab Emirates government responsible for the development of the country's space industry. It was created in 2014 and is responsible for developing, fostering and regulating a sustainable and world-class space sector in the UAE.
The agency is charged with the growth of the sector through partnerships, academic programmes and investments in R&D, commercial initiatives, and driving space science research and exploration.
The Australian Space Agency is Australia's national agency responsible for the development of Australia's commercial space industry, coordinating domestic activities, identifying opportunities and facilitating international space engagement that include Australian stakeholders. Its headquarters are located in Adelaide, the southeastern capital city of South Australia.
The European Space Agency,is an intergovernmental organisation of 22 member states dedicated to the exploration of space. Established in 1975 and headquartered in Paris, ESA has a worldwide staff of about 2,200 in 2018 and an annual budget of about €6.5 billion in 2021.
ESA's space flight programme includes human spaceflight (mainly through participation in the International Space Station program); the launch and operation of unmanned exploration missions to other planets and the Moon; Earth observation, science and telecommunication; designing launch vehicles; and maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana. The main European launch vehicle Ariane 5 is operated through Arianespace with ESA sharing in the costs of launching and further developing this launch vehicle. The agency is also working with NASA to manufacture the Orion Spacecraft service module that will fly on the Space Launch System.
The agency's facilities are distributed among the following centres:
ESA science missions are based at ESTEC in Noordwijk, Netherlands;
Earth Observation missions at ESA Centre for Earth Observation in Frascati, Italy;
ESA Mission Control (ESOC) is in Darmstadt, Germany;
the European Centre for Space Applications and Telecommunications (ECSAT), a research institute created in 2009, is located in Harwell, England;
and the European Space Astronomy Centre (ESAC) is located in Villanueva de la Cañada, Madrid, Spain.
The European Space Agency Science Programme is a long-term programme of space science and space exploration missions.
Don't let the name fool you: a black hole is anything but empty space. Rather, it is a great amount of matter packed into a very small area - think of a star ten times more massive than the Sun squeezed into a sphere approximately the diameter of New York City. The result is a gravitational field so strong that nothing, not even light, can escape. In recent years, NASA instruments have painted a new picture of these strange objects that are, to many, the most fascinating objects in space.
The idea of an object in space so massive and dense that light could not escape it has been around for centuries. Most famously, black holes were predicted by Einstein's theory of general relativity, which showed that when a massive star dies, it leaves behind a small, dense remnant core. If the core's mass is more than about three times the mass of the Sun, the equations showed, the force of gravity overwhelms all other forces and produces a black hole.
Scientists can't directly observe black holes with telescopes that detect x-rays, light, or other forms of electromagnetic radiation. We can, however, infer the presence of black holes and study them by detecting their effect on other matter nearby. If a black hole passes through a cloud of interstellar matter, for example, it will draw matter inward in a process known as accretion. A similar process can occur if a normal star passes close to a black hole. In this case, the black hole can tear the star apart as it pulls it toward itself. As the attracted matter accelerates and heats up, it emits x-rays that radiate into space. Recent discoveries offer some tantalizing evidence that black holes have a dramatic influence on the neighborhoods around them - emitting powerful gamma ray bursts, devouring nearby stars, and spurring the growth of new stars in some areas while stalling it in others.
Most black holes form from the remnants of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to trap light.) If the total mass of the star is large enough (about three times the mass of the Sun), it can be proven theoretically that no force can keep the star from collapsing under the influence of gravity. However, as the star collapses, a strange thing occurs. As the surface of the star nears an imaginary surface called the "event horizon," time on the star slows relative to the time kept by observers far away. When the surface reaches the event horizon, time stands still, and the star can collapse no more - it is a frozen collapsing object.
Even bigger black holes can result from stellar collisions. Soon after its launch in December 2004, NASA's Swift telescope observed the powerful, fleeting flashes of light known as gamma ray bursts. Chandra and NASA's Hubble Space Telescope later collected data from the event's "afterglow," and together the observations led astronomers to conclude that the powerful explosions can result when a black hole and a neutron star collide, producing another black hole.
Although the basic formation process is understood, one perennial mystery in the science of black holes is that they appear to exist on two radically different size scales. On the one end, there are the countless black holes that are the remnants of massive stars. Peppered throughout the Universe, these "stellar mass" black holes are generally 10 to 24 times as massive as the Sun. Astronomers spot them when another star draws near enough for some of the matter surrounding it to be snared by the black hole's gravity, churning out x-rays in the process. Most stellar black holes, however, are very difficult to detect. Judging from the number of stars large enough to produce such black holes, however, scientists estimate that there are as many as ten million to a billion such black holes in the Milky Way alone.
On the other end of the size spectrum are the giants known as "supermassive" black holes, which are millions, if not billions, of times as massive as the Sun. Astronomers believe that supermassive black holes lie at the center of virtually all large galaxies, even our own Milky Way. Astronomers can detect them by watching for their effects on nearby stars and gas.
Historically, astronomers have long believed that no mid-sized black holes exist. However, recent evidence from Chandra, XMM-Newton and Hubble strengthens the case that mid-size black holes do exist. One possible mechanism for the formation of supermassive black holes involves a chain reaction of collisions of stars in compact star clusters that results in the buildup of extremely massive stars, which then collapse to form intermediate-mass black holes. The star clusters then sink to the center of the galaxy, where the intermediate-mass black holes merge to form a supermassive black hole.
1. It would take nine years to walk to the moon.
2. Mars is called the Red Planet because of its red coloring, which comes from the large amount of iron oxide – known on Earth as rust – on the planet’s surface.
3. Mercury’s temperature varies from -280° F on its night side to 800° F during the day.
4. If you can spot the Andromeda Galaxy with your naked eyes, you can see something 14.7 billion billion miles away.
5. If you can spot the Andromeda Galaxy with your naked eyes, you can see something 14.7 billion billion miles away.
6. The Sun is 400 times larger than the Moon, but also 400 times as far away, making both objects appear to be the same size in our sky.
7. Jupiter is the largest planet. It could contain the other seven planets in just 70 percent of its volume.
8. Stars don’t twinkle until their light passes through Earth’s atmosphere.
9. If Earth were the size of a tennis ball, the Sun would be a sphere 24 feet across, approximately 0.5 mile away.
10. Of the 9,113 official features on the Moon, a mere 421 (4.6%) are not craters.
11. Driving a car to the nearest star at 70 mph would take more than 356 billion years.
12. Neptune’s moon Triton is the coldest known object in the solar system with an average surface temperature of -391° F.
13. When the Moon is half-full (First and Last Quarter phases), it’s only 10% as bright as the Full Moon.
14. Scientists estimate that the earliest stars formed some 200 million years after the Big Bang.
15. Jupiter’s Great Red Spot, which rotates once approximately every six days, is an anti-cyclonic storm 22° south of the planet’s equator.
16.If you drilled a tunnel through Earth and jumped in, you would reach the other side in 42 minutes and 12 seconds, and your top speed would be 17,670 mph.
17.To escape Earth’s gravity, a spacecraft must travel more than 25,008 mph, or near Mach 33.
18. It takes 1 billion seconds for the light from a star 31.7 light-years away to reach Earth|
19.The International Space Station completes an orbit of Earth in about 90 minutes.
20.Venus’ clouds trap a lot of the Sun’s heat, making its temperature the hottest in the solar system: 863° F.
21.ONE MILLION EARTHS CAN FIT INSIDE THE SUN.
22.THERE ARE MORE TREES ON EARTH THAN STARS IN THE MILKY WAY.
23.The hottest planet in our solar system is 450° C.
24.Halleys Comet won't orbit past Earth again until 2061.
25.Neutron stars can spin 600 times per second.
Our Team is Group of two Kids of 7th class from Sanghamitra School, Hydernagar, Hyderabad, Telangana, India-500072
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