Have you ever looked out into the vast space that surrounds you and wondered about the Earth on which you live? It is interesting to know that what exactly happened in our universe, about 15 billion years ago.
● All matter in the universe was concentrated in one mass.
● This super dence and extremely hot mass eventually exploded with the Big Bang, and the matter was thrown around in all direction.
● The universe started to expand and get bigger thus creating more space around the matter.
● This scattered matter led to the formation of galaxies, stars and other heavenly bodies.
All of this has been explained by a widely accepted theory called the Big Bang. The theory explain the process that led to the birth of our universe.
With the big bang, millions of galaxies, each having millions of stars, Where are formed in the universe. One such galaxy, to which our Sun belongs, is the Milky Way galaxy. This spiral shaped Galaxy is also known as Akash Ganga( in hindi).
Stars make up the galaxies in the universe. Stars are heavenly objects that are self luminous, i.e. they shine by producing their own light. This incredible amount of light and heat is produced by the burning of gases within them. The sun that we see everyday, is a star.
Some stars make a recognisable pattern in the sky known as constellation or Nakshatra. When you look up into the sky you will see some of them. The most easily recognisable constellations are :
- Ursa Major (the great bear)
- Orion (the Hunter)
- Libra (the Balance Scales
Astronomy is the study of stars and other celestial bodies. Scientists who study the stars and other celestial bodies are called astronomers.
Our Sun, together with all the planets that revolve around it, their satellites or moons, meteors, comets and asteroids, forms the solar system. ‘Sol’ in latin means the Sun, so the sun and all heavenly bodies related to it make up the solar system.
- Our solar system was formed about4.6 billion years ago.
- Th sun, the planets and other celestial bodies have their own gravity of different strengths. This pull on each other, is what holds them in place in the solar system and keep them where they are.
- Each planet struck a certain amount of time to complete one Revolution around the sun. This is called it’s year. The father of planet is from the sun, the longer is it’s year. Mercury, the closest planet to the sun, has a year of 88 Earth days. Neptune, the planet farthest from the sun, as a year of 60,266 Earth days. The Earth takes 365 1/4 days to complete one Revolution around the sun.
Celestial bodies that revolve around the planets are called satellites.
•While the moon is the only natural satellite of the earth, other planets have a higher number of satellites.
•Like the planets, the satellites have no light of their own, and they too reflect the light they receive from the sun.