Who was the first Indian astronaut to travel into space?

Describe the Ptolemaic model for planetary motion.

Which one of the following is known as $Saptarishi$?

$A$ galaxy is observed to be moving with a velocity of $8600 \ km \ s^{-1}$. If it is at a distance of $430$ million light-years from us,the Hubble constant and the corresponding age of the universe are respectively:

Hubble's law states that the velocity with which a galaxy is moving away from the Earth is proportional to:

How does the red shift confirm that the universe is expanding?