THE COSMOS

Cosmos is a term used in astronomy as well as physics. It refers to everything that exists-from the smallest atoms to the huge heavenly bodies that are far away from us. This word has come down from the ancient Greek word kosmos, which means well-ordered universe or world. The Greeks believed that cosmos was a homogeneous (uniform) system consisting of the earth, the sun, the moon, stars, and other visible planets. But today we know that the cosmos is far larger than the one that the ancient people thought it to be. The term cosmos is another word for universe indeed.

COSMOLOGY

Cosmology means study of the origin, structure, development, behavior and future of the cosmos (universe).

Till the l7th century A.D., people believed that everything beyond the earth's surface was not worth knowing at all. But then Kepler proved that a number of heavenly bodies (planets) revolved round the sun. Also, Isaac Newton explained how gravity forced the planets to move along fixed paths. It Ied the scientists to believe that laws of physics were applicable to cosmic bodies as well.

In 1915, Fred Hoyle, suggested that the cosmos (universe) has always existed. New matter keeps being created out of nothing to fill the empty spaces caused due to the expansion of the universe. But a few years later, Edwin Hubble put forth the Big Bang Theory regarding the origin of the universe. This theory came to be accepted finally before long.

These theories goaded the scientists and astronomers to take up a regular study of the cosmos as an independent branch of science. It is this very branch that has been named cosmology.

Astronomers of today are studying the universe from various angles. So, new facts and theories are sure to be put forth to replace the old ones in the near future.