Online Maths Theory and Practices for Kids

What is the Universe?

z The Universe The universe is a vast infinite space which includes the earth and all the heavenly bodies in the sky. The sky contains the Sun, Planets (their moons), Stars, Galaxies, Comets, Asteroids and Satellites.


Star is a heavenly body which has light of its own. You can see stars twinkling in the sky at night. At the moonless night and try to count the number of stars which you can see with your naked eye. You may be able to count around 2000 to 3000 stars in your naked eye. But help of a small telescope you can see around 100,000 stars and most powerful one you can see more than millions (1,000,000) & trillions (1,000,000,000,000) stars.

The stars are very large object and several times bigger than our earth. Some are very small and some are even bigger than the sun. They appear so small because they are very far away from us.

The Sun is also a star and it gives off light all the time.


The Universe, Planets Planets Planets are the heavenly bodies which revolve around the sun. They do not produce their own light but reflect the light of the sun that falls on them. Planets are disc shaped. The planets are not twinkle, brighter than stars. There are eight planets comprised in our universe.

» Learn more about solar system


A vast collection of stars, dust and gas held together by the gravitational attraction between its components. Galaxies are usually classified as Elliptical, Spiral or Irregular shape.

The Universe, Elliptical Galaxies
Elliptical Galaxies
are like ellipsoidal clouds of stars with little internal structure apart from a denser nucleus.

The Universe, Spiral Galaxies

Spiral Galaxies
are flat disc shaped collection of stars with prominent spiral arms.

The Universe, Irregular Galaxies

Irregular Galaxies have no apparent structure or shape.

Milky Way System

The Milky Way System is a galaxy that belongs to our Solar System. There are some 300 billion stars in the system. The age of the system is more than 13 billion years. Most of the stars in the Milky Way lie in the galactic disk close to the nucleus. Our Solar System lies about 28,000 light years from the centre.

The Universe, Milky Way System

Light Year

A light year means for “The Distance Travelled by Light in One Year”. The speed of the light is 300,000 km per second. Therefore one light year is 9.5 X 1,000,000,000,000 (10 Trillion) kilometers.

The sun is nearly 8 light minutes away from the earth. It means that light from the sun takes nearly 8 minutes to reach the earth.