Question

According to astronomers, what is a "light year"

Answer 1

Here's a hint : A light year is a distance, not a time.

A light year is a unit of length used informally to express astronomical distances.

Answer 2

A light year is the distance light travels in one year.

Let's figure out what this distance is shall we...?

We know that speed = distance / time, therefore distance = speed x time.

Speed of light = 299,792,458 m/s

Time (One year) = 31,536,000 s

That is a ridiculous:

9.454254955 x 10¹⁵ metres,

Which is approximately:

9,400 trillion metres.

Only "one light year" away... That's a hell of a distance.