Answer:
Lightyears
Explanation:
When dealing with very large interstellar distances, astronomers do not use the regular miles, kilometers, or meters we are used to. This is because they are just too small to be used as a metric when measuring such large distances. As a matter of fact, the earthly number system will quickly be exhausted when trying to measure some of these interstellar distances.
Instead, astronomers make use of Lightyears. Lightyears are defined by the distance traveled by an object moving at the speed of light if it was moving constantly at that speed for one year.
This can properly be used to estimate interstellar distances. since its value is very large. 1 lightyear = 9,461,000,000,000 Km
If we say that our closest star is 9 lightyears away, we are saying that it will take an object moving at the speed of light 9 years to travel from that star to our planet.
