The farthest objects in our Universe discovered by modern astronomers are so distant that light emitted by them takes billions of years to reach the Earth. These objects (known as quasars) have many puzzling features, which have not yet been satisfactorily explained. What is the distance in km of a quasar from which light takes 3.0 billion years to reach us?
Quasar: The active galactic centre which emit huge amount of energy in the form of light.
Given,
Time taken by Quasar light to reach earth, T = 3 billion years
∴ T = 3×109×365×24×60×60 s
(∵ 1 billion = 109 years)
We know that,
Speed of light in vacuum, V = 3×108 m/s
∴ Distance between the Earth and Quasar is given by,
D= V×T
= 3×108×(3×109×365×24×60×60) m
= 2.8×1022 km