The speed of recession of a galaxy is proportional to its distance.

What is a Red Giant?

The length of the Milky Way is .......... light years.

Meteors are

$A$ 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:

The magnitudes of two stars $A$ and $B$ are $2.5$ and $-5$ respectively. The brightness ratio of $\frac{B}{A}$ is