User talk:ATULIT RANJAN

THE MYSTERIOUS UNIVERSE

THE UNIVERSE is vast beyond our imagination. It is all of space and time and its contents planets, stars, galaxies, and all other forms of matter and energy. UNIVERSE is often defined as the totally of everything that exists. About billions of years ago, the universe was a small ball it was smaller than the smallest thing we imagine and this tiny ball exploded, it was not just a small explosion it was a huge explosion with the strength of millions of nuclear bombs and this massive explosion is what we called the BIG BANG, all the matter even every star, rocks, asteroids, meteoroids, dust, and every grain of sand on the earth, and everything was thrown in this explosion that’s how the universe was born. It is estimated that the universe contains billions of galaxies, and each contains billions of stars. The universe is expanding every time since the big bang and this expanding process is not stopping because there is no friction in space.

GALAXY

A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. There are billions of galaxies in the universe and we also live in a galaxy named MILKY WAY. The galaxy holds its special place in space. When the sky is clear, like a cloud in space, a band is visible at the night. Due to this strip, there are countless stars in this imagined river of stars. Seeing them, it appears as if there are particles of silver. Seeing this, people have it named galaxy. Many stars were found in space. Scientists have discovered many new galaxies. The distance of one of these is estimated to be 1000 million light years from Earth. A team of astronomers in the United States has discovered a galaxy that is probably the farthest away from all known galaxies. Its distance is 145 billion light years. The largest known distance is 2–3 billion light years away from Aakash Ganga. This galaxy was discovered accidentally by Professor Byron Spaniard of the University of Berkeley when his team was examining the new transparent light combination in the telescope. Further study is necessary for more information regarding this.

STAR When you look up at the sky on a clear night, you see a large number of twinkling stars. A nursery rhyme says:                                                                                                                                “Twinkle, twinkle little star;                                              How I wonder what you are!”                                                           A star is an astronomical object, and a hot ball of gasses, mostly hydrogen and helium. They emit their light, which makes them to visible or shine. We cannot see the other stars during the daytime because of the bright sunlight. Stars are much bigger than the earth. Our sun is about 13 lakhs times bigger than the earth. Some stars are even bigger than the SUN. They appear small because they are very far away from us. When seen from the earth, stars appear east to west because our earth rotates west to east. However, one star appears stationary when seen from the earth. This is the Pole star or Polaris (or Dhruv Tara). The Pole star appears stationary because it lies on the imaginary axis of rotation of the Earth. Stars are not permanent. They are formed from gases-mainly hydrogen and end up as a white dwarf or as a neutron star. The other stars in the sky are much further away from Earth than the Sun. The closest one after the Sun is called Proxima Centauri and it takes 4. 22 years for light from it to reach Earth. All other stars are even further away. The light of almost all the stars we can see in the night sky has been travelling for hundreds, thousands, or even tens of thousands of years before reaching our eyes. Even though we see them, some of these stars may not exist anymore, but we do not know it yet because the light of their explosion has yet to reach us when they die. Distances in space can be measured in terms of light-years, which is the distance light travels in one year A light-year is almost 6,000 billion miles (around 9,500 billion km).

NEUTRON STAR

When stars much more massive than the Sun run out of fuel, they usually expel all their outer layers in a giant explosion called a supernova. Such an explosion is so powerful and bright that it can outshine the light of billions of stars. But sometimes not everything is expelled in such an explosion, Sometimes the core of the star can remain behind as a ball. After a supernova explosion, this remnant is very hot. around 180,000 degrees Fahrenheit (100,000 degrees Celsius), but no more nuclear reaction exists to keep it hot. Some remnants are so massive that they collapse in on themselves under the influence of gravity until they are only a few dozen miles across. For this to happen, these remnants need to have a mass that is between around 1.4 and 2.1 times the mass of the Sun. The pressure is so intense inside these balls that they become liquid inside, surrounded by a thick solid crust about a mile (1.6 km). The liquid is made of particles that normally remain inside the core of the atoms - the neutrons - so these balls are called neutron stars. There are also other particles inside neutron stars, but they consist mostly of neutrons. To create such a liquid on Earth is beyond our present technology. Stars like the Sun do not explode in supernovae but become red giants whose remnants are not massive enough to shrink under their gravity. These remnants are called white dwarfs. White dwarfs cool down throughout billions of years until they are not hot anymore. Many neutron stars have been observed by modern telescopes. Since the cores of stars are made of the heaviest elements forged inside stars (like iron), although white dwarfs can be quite small (about the size of the Earth) they are extremely heavy (about the mass of the Sun).

The Life of a Star

A galaxy is a huge mass of stars, nebulae, and interstellar dust and gases. Nebulae are clouds of dust and gas (mainly hydrogen and ionized hydrogen) that float in space. Often, the force of gravity pulls the particles of gas and dust closer into a swirling mass. The spinning cloud will start to glow if the mass is heavy enough. This is a protostar or the first stage before a star is born. Stars are self-luminous bodies of hot and glowing gas (hydrogen) born inside the nebulae themselves. Our Sun is a small star. Massive stars may have a mass of at least three times that of the Sun and some stars as massive as 50 times the Sun exists. Stars produce energy by nuclear fusion at the core. After millions to billions of years, the core contracts when the hydrogen starts running out while the outer portion continues expanding. The star is now called a red giant. The amount of mass a star has determined the rest of its life cycle. The cores of low-mass stars collapse, expelling the outer layers and forming a nebula. The core remains a white dwarf and eventually cools to become a black dwarf. A massive star will undergo a supernova explosion. If the remnant of the explosion is 1.4-3 times as massive as the Sun, it will become a neutron star. After the explosion, a star with a core more than three times the Sun will be swallowed by its gravity. It now becomes a black hole that can readily attract any matter or energy that comes near it.

CONSTELLATIONS

A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived outline or pattern, typically representing an animal, mythological subject, or inanimate object. In Indian terminology, constellations are called nakshatras. So far, 88 constellations have been recognized and named. Some important constellations are described on the next page.

Ursa Major (or Great Bear)

Ursa Major constellation consists of seven bright stars. These seven stars are arranged in the form of dipper-three stars in the handle and four in its bowl. That is why this constellation is also known as the Big Dipper. The name the Big Dipper is derived from the word dipper-a utensil used in the olden days to drink water. Ursa Major is also called Great Bear (or saptarishi) because the seven bright stars of Ursa Major along with several other fainter stars form a pattern resembling a bear. Ursa Major can be seen clearly in April in the northern hemisphere at night. The Pole-star, commonly known as Dhruva Tara always remains at the same fixed position in the sky. It lies on the northern end of the extended line drawn through the two stars at the end of Ursa Major.

Ursa Minor (or Little Bear)

The Indian name of the Ursa Minor (or Little Bear) constellation is Laghu saptarishi. Ursa Minor (or Little Bear) contains seven bright stars. At the end of the tail, the star is the Pole star (Dhruv Tara). The arrangement of stars in Ursa Minor is shown alongside. Ursa Minor constellation is sometimes also called the Pole star constellation. In the northern hemisphere, Ursa Minor can be seen clearly at night (towards the north) in the months of June-July.

Orion (or the Hunter)

Orion is also known as Kalpurush. There are seven bright stars and several faint stars in Orion. The arrangement of stars in Orion resembles a hunter. The three middle stars represent the belt, and the four bright stars (two above and two below the belt) describe the shoulder and legs of the hunter. Orion is visible in the northern sky in the late evenings during winter. BLACK HOLE

A black hole is a region where gravity is so strong that any light that tries to escape gets dragged back. Because nothing can travel faster than light, everything else will get dragged back too. So you can fall into a black hole and never get out again. A black hole has always been thought of as the ultimate prison from which there's no escape. Falling into a black hole is like falling over Niagara Falls: there's no way of getting back the same way you came. The edge of a black hole is called the horizon. It is like the edge of a waterfall. If you are above the edge, you can get away if you paddle fast enough, but you are doomed once you pass the edge. As more things fall into a black hole, it gets bigger and the horizon moves further out. black holes are formed is when stars that have burned up their fuel explode like giant hydrogen bombs called supernovas. The explosion will drive off the star's outer layers in a great expanding shell of gas and push the central regions inwards. A black hole will form if the star is more than a few times the size of our Sun. Much larger black holes are formed inside clusters and in the centre of galaxies. These regions will contain black holes, neutron stars, and ordinary stars. Collisions between black holes and other objects will produce a growing black hole that swallows anything that comes too near it. Our galaxy, the Milky Way. If you fall in feet first, your feet will be nearer to the black hole than your head and will be pulled harder by the gravity of the black hole. So, you will be stretched out lengthwise and squashed sideways. This stretching and squeezing are weaker the bigger the black hole is. If you fall into a black hole made by a star only a few times the size of our Sun, you will be torn apart and made into spaghetti before, " you even reach the black hole. But if you fall into a much bigger black hole, you will pass the horizon - the edge of the black hole and the point of no return - without noticing anything in particular. However, someone watching you fall in from a distance will never see you cross the horizon because gravity warps time and space near a black hole. To them, you will appear to slow down as you approach the horizon and get dimmer and dimmer. You get dimmer because the light you send out takes longer and longer to get away from the black hole.

THE SOLAR SYSTEM

The SOLAR SYSTEM is the family of the Sun, the eight planets, their satellites, dwarf planets, asteroids, meteorites, comets, and many other celestial bodies. Our SOLAR SYSTEM is located in the ORION ARM around two-thirds from the central bulge of the milky way, which turns once every 220 million years. The age of the SOLAR SYSTEM is 4.6 billion years. The sun is the head of the solar family and the other bodies orbit it. The Solar planets are divided into an inner system of four planets or terrestrial planets from Mercury to Mars and an outer system of four much larger planets from Jupiter to Neptune. Between the above two planetary systems is a belt of asteroids containing pieces of rocks of varying sizes.

SUN

The sun is the closest star to us and the centre of the SOLAR SYSTEM. All the planets and the other celestial bodies in the solar system are bound to the sun by its gravity. All the planets in the solar system revolve around the sun in a fixed orbit. the sun’s diameter is about 1,392,000 km. Three-fourths of the sun’s mass is hydrogen and almost one-fourth of its mass is helium. Hydrogen nuclei fuse to form helium and in this process, some mass gets converted into huge energy according to Einstein’s mass is equivalence to energy law(e=mc2).

THE PLANETS IN THE SOLAR SYSTEM ARE DESCRIBED BELOW:

MERCURY

Mercury is the smallest and closest planet to the sun. It has no atmosphere, therefore the days are so hot (427 degrees Celsius) while at night temperature drops hundreds of degrees below the freezing point (-173 degrees Celsius). There is no life on Mercury. Mercury rotates from east to west completing one rotation in about 59 earth days and completing one revolution in 88 earth days. It has no moons. Life doesn’t exist in mercury.

VENUS

The VENUS is the second closest planet to the sun and the second smallest planet in the SOLAR SYSTEM. It is the brightest planet of the SOLAR SYSTEM therefore it is also called the shining planet. Venus is called the morning and evening stars. Its size is nearly equal to the size of the earth so it is also called the earth’s twin brother. You will be surprised to know that Venus is the second closest planet to the Sun but it is hotter than Mercury because the amount of greenhouse gases in the atmosphere of Venus is high which allows the heat of the Sun to come in but does not let the heat go back. It also rotates from east to west. Venus completes one rotation in 243 earth days and a revolution in 225 earth days. It has no moons. There is no evidence of life on Venus.

EARTH The earth is the third closest planet to the sun and the fifth largest planet in the SOLAR SYSTEM. Earth is unique because it is the only planet where life exists. Life is possible on the earth because the earth has the best conditions for sustaining life like it is at a favourable distance from the sun, 71% of its surface is water in rivers, ponds, lakes, polar caps, and oceans and the remaining 29% is land. Its gravity is sufficient to hold an atmosphere, and it has a layer of ozone that protects us from the harmful sun’s harmful rays atmosphere consists mostly of nitrogen (78%) and oxygen (21%). The earth is about 149.6 million kilometres far from the sun. Its diameter is about 12,756 km. Earth is an ellipsoid with a circumference of about 40,000 km. It is the densest planet in the Solar System. Of the four rocky planets, it is the largest and most massive. Earth is about eight light minutes away from the Sun. The earth completes one rotation in 24 hours, but in fact, it takes only 23 hours, 56 minutes, and 4 seconds. 3 minutes and 56-second mismatch. And completes one revolution in 365 days and 6 hours, but one year is only 365 days these 6 hours are added to the leap year of 366 days. The earth has one moon. The earth’s axis is 23.5 degrees tilted therefore at the poles it is 6 months day and 6 months night. The earth’s orbital speed is 29.78 km/s. So far, the earth is the only planet to harbour life.

MARS

Mars is the fourth closest planet to the sun. Mars is nearly half the size of the earth. It is the only planet on which life is likely to exist. . It is 141 million miles from the Sun and 48 million miles from the Earth. Its diameter is 4140 miles, almost half of the Earth. Mars is a reddish planet because of its surface’s oxidized iron. That is why it is also known as the ‘Red Planet. Mars is a rocky planet with an iron core. The atmosphere is found around Mars. It has a very thin atmosphere mostly made of carbon dioxide. The largest solar system volcano is on mars, OLYMPUS MONS. It is about three times Mt Everest. It completes its orbit around the Sun in about 2 years and rotates on its axis once in 2 hours and 10 minutes. There are seasons here too; Because the axis of Mars is tilted in its orbit. The maximum temperature at the equator of Mars goes up to 20 degrees centigrade during the day and -50 degrees centigrade at night. The colour of Mars is red and it is visible in the evening time. Mars has two satellites or moons which revolve around Mars. Their names are Phobos and Deimos. Both these satellites were detected in the year 1877. Altogether, life cannot exist on mars.

JUPITER Jupiter is the fifth closest planet to the sun. It is about 778.3 million km far from the sun. If Google is to be believed, it was discovered by William Herschel in 1781, but the planet Jupiter is also discussed in Hindu texts by the name of Brihaspati, and these texts were written thousands of years ago in the later Vedic period. It is the largest planet in the solar system. It is so large that 1300 earth can be placed in it. Even though it is so big, its speed is very fast. It completes its rotation in only 9 hours and 56 minutes. And it completes one revolution in 12 earth years. It is also called a failed star. It has a very thick atmosphere; it consists mainly of helium and hydrogen in its atmosphere. It has a GREAT RED SPOT on its surface. It is the largest storm in the solar system. It is believed that 3 piles of earth can be placed in it. It produces wind speeds up to 432 km/h. Jupiter has 79 moons. Ganymede [the solar system’s largest moon], Io, and Europa are the main moons of Jupiter. SATURN

Saturn is the sixth closest planet to the Sun and the second largest planet in the solar system. It has a ring of dust, ice, and meteors. It is a gas giant. Its average distance is 1430 million km. It takes about 10.7 earth hours to complete one rotation on its axis and it takes about 29 earth years to compete for one revolution around the Sun. it is also known as SANI. It is discovered by Galileo in 1610. It has a hot rocky core surrounded by a liquid metal layer, which is itself surrounded by liquid hydrogen and helium. Then it is an atmosphere that surrounds it all. Saturn has 59 confirmed moons. Titan is the largest moon of Saturn, Titan is three times bigger than our moon. Titan is the only moon in the solar system which has an atmosphere. So far, it has no favourable conditions to harbour life.

URANUS

Uranus is the seventh closest planet to the Sun and the second farthest planet from the sun. It has a very cool temperature. It is about 2870 million km far from the sun. Uranus takes about 84 earth years to a revolution around the sun and it takes about 0.718 days to complete one rotation on its axis. It has 27 moons. It was discovered by William Herschel in 1781 with the help of a telescope. In its atmosphere, hydrogen and methane gas have been detected. It has no favourable conditions to harbour life.

NEPTUNE Neptune is the farthest planet from the Sun. It is the eighth planet to the Sun. It is about 4498 million km far from the Sun. it takes about 165 earth years to complete one revolution around the Sun and it takes about 0.617 earth days to rotate on its axis. U.J. Le Verrier predicted the existence of a planet beyond Uranus in 1846. He even predicted its mass, size, and position in space. Later astronomers discovered Neptune with the help of telescopes. It has 14 moons of which 13 moons are confirmed and 1 moon is under-confirmed. It has an atmosphere like Uranus. It has no favourable conditions to harbour life.

ASTEROIDS, METEOROIDS AND METEORITES

An asteroid is an icy, rocky, or metallic celestial body. It is a minor planet in the inner solar system. Different asteroids differ in shape and size; some have a size of up to 1000km and some have a size of 1 meter. They have no atmosphere. Scientists discover many asteroids every month. Asteroids are generally classified to be of three types: C-type, M-type, and S-type. These were named after and are generally identified with carbonaceous, metallic, and salicaceous compositions, respectively. In 1801, while making a star map, Giuseppe Piazzi accidentally discovered a small object 1000 kilometres (600 miles) in diameter between the orbits of Mars and Jupiter. Piazzi named the object Ceres. It was the first asteroid to be discovered. Scientists discover hundreds of asteroids every month. A meteoroid is a small rocky or metallic body in outer space. Meteoroids are defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as micrometeoroids or space dust. When meteors travel at high speeds. When meteors enter the earth’s atmosphere, they get heated up due to air friction and become visible. Meteors often burn out in the air, but sometimes a meteor does not burn completely on its entry into earth’s atmosphere and lands on the earth. And this object is known as a meteorite.

SPACE AGENCIES A government or non-government agency engaged in outer space and exploration activities is known as a Space Agency. There are so many space agencies in the world. Every country has its space agency. Given below is a list of major space agencies of the world: Indian Space Research Organisation (ISRO) – INDIA

National Aeronautics and Space Administration (NASA) – USA

Russian Federal Space Agency (RFSA) – RUSSIA also known as ROSCOSMOS

China National Space Administration (CNSA) – CHINA European Space Agency (ESA) – EUROPE Japan Aerospace Exploration Agency (JAXA) – JAPAN

All the above space agencies are government space agencies, but there is also a non-governmental space agency. And the name of that agency is Space Exploration Technologies Corporation (SpaceX) is owned by ELON MUSK.

THE SPACE RACE BETWEEN TWO COLD WAR RIVALS

The space race was the 20th-century competition between two cold war rivals, the United States, and the Soviet Union. In about 1955, both superpowers were developing Ballistic Missiles. The competition began on July 30, 1955, when the United States announced that it will become the 1st country to launch satellites into outer space. But, on the 4th of October 1957 Soviet Union achieved the first successful satellite launch, Sputnik 1. At that time, the United States and the whole world were surprised. On 6 December 1957, the United States launched a satellite but this mission was unsuccessful and the whole world was trolling the United States. The Soviet Union won the race to launch a satellite into outer space. In 1958, the USA established a space agency NASA. This was the birth of NASA. The US announced that they will send a human to space in 1962. On 12th April 1961, USSR launched the Vostok satellite. In this satellite, Yuri Gagarin became the first person to go to space. And he also revolved around the earth in space in 108 minutes and safely came back to the earth. After this incident, the USA sent a satellite to Earth’s orbit. In August 1961, the Soviet Union send Vostok 2, which revolved 17 times around the Earth and came back to Earth in 25 hours. In 1962, the USA sent a spacecraft to space, it revolved around the earth for one time and came back to Earth. Till then, the Soviet Union was winning the race. But on 12th September 1962, John F Kennedy, the President of America delivered a speech he promised to put an American astronaut on the moon before the end of the 1960s. And finally, on 16 July 1969, the USA launched APOLLO. On 20 July 1969, it landed on the moon’s surface. And the USA became the first country to send a man to the moon. And that lucky man was Neil Armstrong. And the space race ended in some fields the Soviet Union won but in other fields the USA won.

I hope you have understood about the universe. This knowledge of the universe is not even equal to a drop of the ocean like the universe. Right now we have very little information about the universe.