The diameter of Milky Ways is over ----- light years.

Define one light year.

What is light year?

Let us assume that our galaxy consists of 2.5 × 10^(11) stars each of one solar mass. How long will a star at a distance of 50,000 ly from the galactic centre take to complete one revolution? Take the diameter of the Milky Way to be 10^(5) ly.

What is one light year?

The diameter of eyeball is __________.