example...."the galaxy is about 20 light years away"
2007-04-30 06:11:15 · 17 answers · asked by trey 2 in Science & Mathematics ➔ Astronomy & Space
A lightyear is a unit of measurement of length, specifically the distance light travels in vacuum in one year. Also The exact length of the light-year depends on the length of the reference year used in the calculation.
1 light year = 5.87 x 10^12 miles or 9.46 x 10^12 km. based on a reference year of exactly 365.25 days.
When you say the galaxy is 20 lightyears away it means that the distance of the galaxy from the reference point which is the earth is equal to 189,214,609,451,616 Km.
2007-04-30 06:23:05 · answer #1 · answered by giftedman88 3 · 0⤊ 0⤋
A light year is how far light travels in one year at the speed of 186,262 miles a second. About 5.878 trillion miles. A larger unit used is a parsec, which is 3.26 lightyears.
The Milkyway Galaxy is about 100,000 lightyears across, therefore, any reference to something in space that less than 100,000 lys is within our own galaxy. Anything greater, is outside our galaxy!
hope this helps
2007-04-30 06:34:59 · answer #2 · answered by James O only logical answer D 4 · 0⤊ 0⤋
They mean a distance of about 6 trillion miles.
Light moves at 186,000 miles per second and if you traveled at that speed for a year you would cover almost 6 trillion miles. It is like saying some place in the city is 20 minutes away meaning that if you drive at some assumed speed for 20 minutes you will get there.
2007-04-30 06:21:04 · answer #3 · answered by campbelp2002 7 · 0⤊ 0⤋
A lightyear is the distance light travels in one year.
2007-04-30 06:13:51 · answer #4 · answered by Anonymous · 0⤊ 0⤋
A lightyear is a measure of distance. It means the distance light travels in one year.
5,879,000,000,000 miles
2007-04-30 06:15:54 · answer #5 · answered by biscuitperifrank 5 · 0⤊ 0⤋
A common confusion is that light year is a reference to time.
It is a reference to distance: the distance light travels (in a vacuum at 300,000 kilometers/second) in one standard earth year.
By common nomenclature no larger units of distance are used, but you can refer to light months, weeks, days, hours or seconds. For example, the sun is about 8 1/2 light minutes from earth.
2007-04-30 06:20:11 · answer #6 · answered by Lorenzo Steed 7 · 0⤊ 0⤋
A light-year or lightyear (symbol: ly) is a unit of measurement of length, specifically the distance light travels in vacuum in one year. While there is no authoritative decision on which year is used, the IAU recommends the julian year.
2007-04-30 06:14:24 · answer #7 · answered by SamCam 6 · 0⤊ 0⤋
The distance light travels in one year. This distance is about 5.87849981 × 10^12 miles
2007-04-30 11:03:01 · answer #8 · answered by Mr. Smith 5 · 0⤊ 0⤋
One light year means distance travelled by light in one year that is equal to 9.46 tera meters so 20 light year means around
189,200,000,000,000,000 meters so u see it will be a huge number so they express it in light years so it is only 20 light years away, a huge diff in number.
2007-05-03 19:17:03 · answer #9 · answered by ksr 3 · 0⤊ 0⤋
A light year is how far light travels in a year going at 186,262 miles per second.
2007-04-30 06:13:50 · answer #10 · answered by Gene 7 · 0⤊ 0⤋