when refering to distance in space, why is the term "light years" used instead of miles?

Answer 1

Because the numbers of miles become too large for the average person to grasp.

For example, the nearest star to ours is Proxima Centauri, which is 4.2 Light Years away.

Light travels at 186282.3971 miles per second, so one light year is:

186,282.3971 miles/second * 60 seconds/minute * 60 minutes/hour * 24 hours/day * 365.25 days/year = 5,878,625,373,183.61 miles

So Proxima Centauri is 24,690,226,567,371.20 miles away. That's 24 trillion, 690 billion, 226 million, 567 thousand, 371.2 miles.

Isn't it easier to just say 4.2 light years?

The nearest galaxy to the Milky Way is the Andromeda Galaxy, which is about 2½ million light years away. That is 14,696,563,432,959,000,000 miles away (that's 14 quintillion, 696 quadrillion, 563 trillion, 432 billion, 959 million miles away).

Isn't it easier to say two and a half million light years?

Answer 2

Because the distances involved are so great.

One light year is about 6 trillion miles (that's 6,000,000,000,000.) There is nothing except our own Solar System that close to us, the very nearest star being 4.3 light year away, That would be in miles 24,300,000,000,000. Most celestial bodies are hundreds or thousands of times more distant, so the numbers would soon bog down in a mass of zeroes.
Actually, for very large distances, astronomers use a different measure, the parsec, equal to 3.26 light years. That t is the distance at which a star would have an optical parallax of one second of arc as seen from Earth.( PARallax /SECond.)

Answer 3

Light years are used because the distances in space are enormous. If they were measured in miles, then the number of miles would be huge. A light year is a much larger unit than a mile, so the numbers are smaller and easier to use.

Also, the concept of a light year has a practical meaning in astronomy. When you look at a star, you are seeing it by means of the light that it emits. That light takes some time to travel from the star to you. So, when you observe a star that is 5 light years away, you are seeing the star as it was 5 years ago. When you look at very distant objects, you are seeing them very far back into the past.

A light year is the number of miles that light travels in one year, when travelling through a vacuum.
1 light year = 5,878,625,373,183.61 statute miles
1 light year = 9,460,730,472,580.8 km

Answer 4

It allows for easier numbers to deal with. For example, Alpha Centauri, our nearest neighbor, is roughly 4 light years away. If we were to give that distance in miles, it would equate to 2.35 x 10^13 miles. Hence, light years make for easier numbers when gauging astronomical distances.

Answer 5

The Universe is so vast that travel there is measured in "Light Years". Presently, there is nothing faster that we know of than the speed of light. Light travels at 186,000 miles per second. A Light Year is the distance one could travel in one year at that speed.

Answer 6

Because distances in space are so immense and since light travels so fast (faster than anything else) we measure distance in light years, which is how far light will travel in one year. I dont remember how many miles it is, but it's pretty damn far!

Answer 7

Becuase space is infinitly more vast than a planet is. We can still refer to things in miles; but we might find that it eventually becomes inadequate to descibe the imense distances of space.

Answer 8

It takes too much paper to write it out in miles.

Answer 9

Well, i don't. I always use nanometers! :)