The Universe

When we look at the sky, we see different kinds of natural bodies like the sun, the stars, the moon, and so on. The natural bodies in the sky are called celestial bodies or heavenly bodies. They are part of our universe. The universe is a huge space which contains everything that exists. The celestial bodies that we see are just a small fraction of the bodies that exist in the universe. One of the reasons why we do not see more of them is that they are very, very far away.

For the first is we have a Solar System. It is the sun is the brightest object in the sky. It is huge. It is about 333,000 times heavier than the earth, and you could fit more than a million earths inside it! Its great mass causes a large gravitational force. This keeps the sun, the planets, their moons and some other smaller bodies together as the sun’s family. The sun and all the bodies moving around it are together called the solar system. All the members of the solar system revolve around the sun in almost circular paths, or orbits.

There are trillions of stars in the universe. They occur in groups called galaxies. The gravitational force between stars keeps the stars of a galaxy together. Apart from stars, a galaxy may have other celestial bodies like planets and moons. So you can say that a galaxy is a group of stars and other celestial bodies bound together by gravitational force.

The distribution of the stars in a galaxy can give it a shape such as spiral, ring or elliptical. Our sun is a part of a spiral galaxy called the Milky Way Galaxy. This galaxy is named after the Milky Way. The Milky Way is a band of stars that we can see on a clear night. These stars are a part of our galaxy. The ancient Romans called this band of stars Via Galactica, or ‘road of milk’. That is how our galaxy got its name.

Second, there are trillions of stars in the universe. They occur in groups called galaxies. The gravitational force between stars keeps the stars of a galaxy together. Apart from stars, a galaxy may have other celestial bodies like planets and moons. So you can say that a galaxy is a group of stars and other celestial bodies bound together by gravitational force.

Third, is about Planets. We have 8 planets in our solar system. The name of planet is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.  After the sun, the planets are the largest bodies in our solar system. The planets are around body the orbit the sun and which has pulled in all objects near its orbit. The four planets closest to the sun—Mercury, Venus, Earth and Mars—are small, rocky planets. They are called terrestrial planets. The other four planets—Jupiter, Saturn, Uranus and Neptune—are giants in comparison.

            We also have a moon. It around the moon in every single day. In one years, the moon around the in 360 days. The moon takes 27 days and 8 hours to complete one revolution around the earth. In this time it also completes one rotation around its axis.

We see different shapes of the moon as it travels around the earth. 

Because of that, we have a night and morning. Another thing in universe that we cannot see is the dwarf planets, asteroids, meteoroids and comets. The dwarf planets is a small, round body that orbits the sun. In case asteroids is in a belt between the orbits of Mars and Jupiter, millions of small, irregular, rocky bodies revolve around the sun. These are asteroids, and the belt is known as the asteroid belt. Asteroids are also called minor planets. Asteroids were not the only pieces of rock left over from the formation of the solar system. Some others, called meteoroids, still orbit the sun. When they come very close to a planet such as the earth, gravitation pulls them in. A comet is a small body of ice and dust that moves around the sun in an elongated orbit. As a comet approaches the sun, it heats up and leaves behind a stream of hot, glowing gases and dust particles. We see this as the ‘tail’ of the comet. So that is a little thing we know about the universe.