Q: 8.5 Let us assume that our galaxy consists of stars each of one solar mass. How long will a star at a distance of ly from the galactic centre take to complete one revolution? Take the diameter of the Milky Way to be ly.
We know that one light year is .
The time period of rotation is given by :
Putting all the value (in SI units) in the above equation we get :
or
In years :