Question

Why are light-years more convenient than miles, kilometers, or astronomical units (AU) for measuring the distances to stars and galaxies?

Answer 1

Answer:

Stars and galaxies are very far from the Earth. If their distance were denoted by km or AU then the numbers would be very large. Light-year makes the representation of distance to be concise.

Explanation:

Stars and galaxies are very far from the Earth. If their distance were denoted by km or AU then the numbers would be very large. Light-year makes the representation of distance to be concise.

The distance light travels in one year is called a light-year.

$1\ lightyear = 3\times 10^{8}\times 365.25\times 24\times 60\times 60 = 9.46728\times 10^{15}\ m$

As it can be seen here that 1 light year = 9.46728×10¹⁵ m expressing distances of stars and galaxies which are more than 1 light-year becomes easier. Converting it to km will make it 9.46728×10¹² km does not make much difference.

1 Astronomical unit (almost the distance between the Earth and Sun) = 149597870700 m is also not enough to represent the distances of stars and galaxies.