The Big Bang Theory

The Big Bang Theory :

Ø All the matter in the universe was originally a concentrated lump called primeval atom.

Ø Big bang was an explosion that occurred 15 billion years ago, leading to the formation of galaxies of stars and other heavenly bodies.

Ø Since then, all the galaxies have been flying away from one another causing expansion of the universe.

Galaxy

Galaxy :

Ø A Galaxy is a vast system of billions of stars, which also contains a large number of gas clouds (mainly of hydrogen gas) and dust, isolated in space from similar systems.

Ø There are about 100 billion galaxies (10^11 galaxies) in the universe, and each galaxy has, on an average, 100billion stars (10^11 stars). So, the total number of stars in the universe is 10^22 stars.

Ø The Milky Way galaxy is the home of the Earth and our solar system. It is spiral in shape.

Ø Milky Way galaxy was formed 5 billion years after the Big Bang.

Ø Latest known galaxy is the Dwarf Galaxy.

Ø According to the modern thought, universe can be classified into two parts namely :

1.     Atmosphere, and

2.     Space.

Ø Origin of the universe is explained by the Big Bang Theory, formulated and proposed by the Belgian astronomer and cosmologist Georges Lemaitre.

Ø Andromeda is our nearest galaxy.

Universe

Universe :

Ø The Universe is commonly defined as the totality of everything that exists, including all physical matter and energy, the planets, stars, galaxies and the contents of intergalactic space.

Ø The study of universe is nown as Cosmology.

Cosmology = cosmoc (Universe) + logos (Science).

Ø The universe has no limit.