Question

What are the units of measuring space? What is meant by "Light Year" and "Astronomical Unit"?

Answer 1

As outer space is limitless we can measure it only with special units. There are two units of measurement - Light year and Astronomical units.
A Light Year is the distance covered by light in one year in vacuum travelling at a speed of 299,792 km per second. A light year is thus 9,460,530 million km.
Astronomical Unit represents the mean distance between the sun and the earth, calculated on the data supplied by radars. One A.U. is approximately 150 million km. In other words a light year is made up of about 60,000 A.U.