The Universe

The Universe

All the aggregate of all existing things or the whole creation embracing al celestial bodies (heavenly bodies) and all of the space is called the universe.

The Universe

The universe consists of everything that exists including the earth, solar system, constellation, galaxies etc. Solar system in the universe is like a very fine particle. Nobody knows the size and the limit of the universe. The sun is the nearest star to the earth, which is the main source of energy. The sun is so large that if it is a hollow ball, we could place more than one million (1.3) earth into it. It is 1.5*10^8 km away from the earth. All the planets of the solar system revolve around the sun in their elliptical orbits.

Galaxies

Stars are the main constituents of the universe and their distribution in the universe is not uniform. Somewhere their density is high and somewhere is low. In this way, stars form groups. Some groups of stars are very huge. Such enormous system of stars, star clusters, nebulae, dust, and gas: all held together by gravity are called a galaxy. There are about 10^12 galaxies in the universe. The Milky Way galaxy is one of such galaxies, in which our solar system lies.

The Milky Way Galaxy

The Milky Way is a spiral galaxy consisting of hundreds of billions of stars. Our solar system is located in one of the Milky Way’s three spiral arms about 2.5*10^4 light year away from the nucleus or galactic Centre.

Constellation

Constellations are group of some stars, which do not change their location relative to each other and always form a fixed patter. They are small groups of stars. These patterns are easily recognizable. Such constellation were named after gods, heroes etc. At present 88 constellations are known, out of which twelve constellations are used as sign of zodiacs (RASHIS). All the constellations cannot be seen in the sky at the same time or from same position. Some examples of constellations are Ursa Major (Big dipper), Ursa Minor, Draco, Cassiopeia, Sepheus, Orion, etc.

Solar System

Only the sun is a known star, which has a group like solar family and only one planet of it has suitable conditions for organisms to survive on it, is the earth. The solar system consists of the sun and all the objects that surround it. These objects include eight planes as well as smaller body; satellites that orbit them. Although solar system is huge, it is only a small part of a galaxy. The eight planets of the solar system are mercury, Venus, Earth, mars, Jupiter, Saturn, Uranus and Neptune. The definition of planet is given by the convention that

1.       A planet should have its own round orbit (elliptical) around the sun.

2.       Its shape must be round.

3.       Its orbit must not cross the orbit of other planets.

The Pluto was fail to fulfill the last statement, due to which it is kept in the category of Dwarf planets with its satellite, Charon and newly discovered heavenly mass Jena (2003 UB13)

Planets

Planets are those members of solar system, which revolve the sun in their own elliptical orbits. They are called major planets. The size, temperature, revolution time, and rotation time of the planets are different and they are at different distance from the sun. The major planets can be classified into inner planes and outer planets.

Inner planets are those planets which are surrounded with the belt of asteroids; they are mercury, Venus, Earth and Mars. Outer planets are those planets which are beyond the belt of asteroids. They are Jupiter, Saturn, Uranus, and Neptune.

Mercury

The closest planet of the sun and it is about 5.8*10^7 km away from the sun. It can be seen near the horizon shortly after sunset or before sunrise. We need telescope to see it. It is the fastest rotating planet. The mercury has no atmosphere and no satellite. The diameter of Mercury is about 4880km.

Venus

It is the brightest planet of the solar system. It is also known as morning and evening star, because it can be seen in evening and morning. Its diameter is about 12104 km. the Venus also has no moon. This planet has a thick atmosphere of carbon dioxide and cloud of Sulphuric acid and traps solar energy. It is the hottest and brightest planet. Its temperature is about 480 degree Celsius.

Earth

It is the only planet with suitable environment for living things. It is also called green planet. It takes about 24 hour for one rotation and about 365 days for one revolution. The main components of the atmosphere of the earth are oxygen, nitrogen, and water vapor. About two third are of the earth is covered by ocean which is the major sources of water on the earth. The earth is orange shaped and its average diameter is about 12756 km. The Moon is its only one satellite.

Mars

It can be easily identified in the sky by its red color. It is also called red planet. Its diameter is about 6720 km. It takes 24 hours and 37 minutes for the completion of one rotation and about 687 days for the completion of one revolution.

Jupiter

It is the largest planet which is always covered with clouds. The louds form five bright and four dark grey bands on the surface. The main components of its atmosphere are hydrogen and helium. It has 63 satellites. The temperature of its surface is about -150 degree Celsius.

Saturn

It is the second largest planet which is about 1.5*10^9 km away from the sun. Its diameter is about 120585 km. It takes 10 hour 14 minutes to complete one rotation and 2905 years for one revolution. It is recognized because of the prominent rings. Only three rings of them are seen distinctly. There are about 46 satellites of Saturn, the biggest of them is Titan having diameter of 5150 km. Density of Saturn is so less that it can float on water.

Uranus

It is the first planet discovered; in 1781 A.D. Scientists believe that this planet is made up of fluids which may have core of rock. The temperature of its surface is about -216 degree Celsius. Its atmosphere contains mainly hydrogen, helium, and methane. It has about 27 satellites.

Neptune

Neptune was discovered in 1846 AD. The mean distance between the sun and the Neptune is about 4.48*10^9 km and its diameter is about 48000 km. Atmosphere of Neptune is made up of hydrogen, helium, and methane. The orbit of planet overlaps the orbit of the Pluto. It has 13 satellites, Triton of them is biggest.