What is a "Light Year"?

Question

Can someone explain "light years" in terms that an Idiot like me can understand?

Answer 1

The distance light travels in a year.

Answer 2

5,878,625,373,183.61 miles

Like anything else, light takes time to travel over a given distance. Because the speed of light is so fast (670,616,629.2 mph), on our scale we do not notice it, however, on a universal scale it can be noticed. A light year is the distance that a ray of light can travel in one year.

To understand the idea of the speed of light, it might pay to understand how quickly something slower travels, such as sound. Stand at the end of a park and get a friend to throw a rock through a window pane. Watch while this happens. You seeing the pane breaking is light travelling at the speed of light. A split-second later, you will hear the pane breaking. That is the speed of sound. A while later your friend will pass you running. That is the speed of your friend.

Of course the distance above is based on the speed of light in a vacuum (ie there is nothing, not even air, between the source of the light and the observer). Naturally, if anything gets in the way it slows the light down.

Answer 3

This is a distance used in astronomy. Since the distances are so great in the solar system and beyond, there is actually a delay to time between the time we see an event on the sun, for instance and the time it actually ocurred.

An explosion in space may have actually occurred hours, days or years before we see it. But, because it is so far away, light, as fast as it is, takes awhile to reach us.

The speed of light is about 186, 282 miles per second or:

186,282 X60 x 60 X 24 X 365 =

5,874,589,152,000 miles per year

Therefore 1 light year is 5,874,598,152,000 miles

Answer 4

It is sometimes confusing term if light year is assumed as a unit of time just like year.
Light year is a measure of distance just like a meter or kilometer or mile.
Presuming the above two things are clear. It should be understood that it is diffucult to measure the distances celestial objects because they are very very far. So far that the light coming from them has taken several years to reach us and at present we are only able to veiw their state as it existed at the time the light was emitted from them.

Combining the above concepts it was logical for scientist to device a unit of distance which is equivalent to the distance travelled by light in one year. Hence the name light year.

The light travel 3 x 10^10 m/sec so it travels 365 x 24 x 60 x 60 x 3 x10^10 m/year so that is the measure of one light year.

Answer 5

It is a measure of distance, like a foot, or mile but, it is a very very large distance: 5.879 trillion miles.

It is the distance light travels in one year.

Consider that it takes light only 8 minutes to travel from the sun to the earth, and that is 93 million miles. In 1 year there are 65,700 8-minute periods, so in 1 year light travels about 6 trillion miles.

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Answer 6

The distance that light travels in one year

Answer 7

I believe a light year is the distance that light travels in one year.

Answer 8

Hi
A light year is how long it takes light to travel, which is 186,000 miles a second. So, for instant, if we see a galaxy, looking through a telescope, lets say 20 million light years away, it will take 20 million years for the light to reach out eyes. Looking into to space at distant objects they look greyish white in color, because light hasn't reached our eyes. That's why we add , nebula, color, Ha filters to equipment and eyepieces to bring out contrast and color to get a hint of what it might look like. Hoped this helped.

Answer 9

The distance light travels in a vacuum in one year. Light travels roughly 186,000 miles a second. Roughtly 6 trillion miles if memory serves. If I mess up someone will hold me to task.

Answer 10

astronomers use this as a unit of measurement.this is the distance that a ray of light can travel in a whole year.in a whole year the ray can travel a distance of 300000 * 365 * 24 * 60 * 60 = 9460800000000 km.