What do we measure in light years?

Question

for homework.

Answer 1

WHY is because things are so far apart in space, we need a measurement unit that is really really LONG to keep the numbers reasonable.

Also, when you're measuring in light years, if you know how far something is, you know right off how OLD the light you are seeing from it is.

Answer 2

Distance to distant objects like stars and other galaxies.  A light year is the distance light travels in one Julian year in a vacuum.

9,460,730,472,580.8 km

Answer 3

the distance in space s measured in light years

Answer 4

Distance to things in outer space like stars and other galaxies.

Answer 5

One light year is the distance that light travels in one year through a vacuum.(and, of course, most of the Universe is close to being a vacuum). The "year" used for this calculation is usually the Julian year of exactly 365.25 days or 31 557 600 seconds; sometimes the mean tropical year of 31 556 925.9747 seconds is used. Since light travels at 299 792 458 meters per second, using the Julian year one light year equals 9.460 730 473 x 1015 meters, or 9.460 730 473 trillion kilometers. One light year is approximately 5.880 trillion miles.