The speed of light is 300.000 km/s. This means light would travel a distance
of 300,000 km in just one second. Actually we cannot believe it. Such an
incredible one.
Any way it actually covers such a distance because of its high speed.
Now in one minute ie 60 second, the distance = 300,000 x 60 km
Then what about the distance covered in one hour?
That comes to be 300,000 x 60 x 60 km
Now in one day ie in 24 hours? 300,000 x 60 x 60 x 24 km
Then the distance to be covered in one year ie in 365 days, it will be computed as
300,000 x 60 x 60 x 24 x 365 km
As you simplify this you get the distance covered by light in one year.
Such a distance is named as light year.
Hence light year = 9.46 x 1012 km
For a lay man it has to be written as 9,460,000,000,000 km
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Note:
The questioner asks "How long ... ", so he may be thinking that
a light year is some kind of time period, as so many do.
It has to be pointed out immediately that a 'light year' is a distance, not
a time. It's the distance that light travels in one year through vacuum.
The equivalent distance in km is calculated above.
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I too thought about the word 'long'. But 'long' also stands for length ie distance. So I quietly continued explaining in detail ever for a student studying art subjects and not that much familiar with scientific thoughts.
One light year is equal to about 5.88 trillion miles.
0.0000158132211 light-year.
1 trillion light years = 5.87849981 × 1024 miles.
1 light-year is about 5.88 x 1012 miles. To convert a certain number of light-years to miles, you can multiply by this number.
One light year (the distance light travels in one year) is:5,878,625,373,000,000,000,000 miles.
One light year is equal to about 5.88 trillion miles.
exactly 9,460,730,472,580.8 km or 5,878,625,373,183.608 miles
Exactly 1.000 year.
2,937,300,836,700 miles.
6 trillion miles per year.
1 Light year =5.879e+12.
0.0000158132211 light-year.
There are approximately 5.84 x 1012 (5,840,000,000,000) miles in one light year. This information is far from correct. There are 97,909,819,200 miles in a light year. Light travels 186,282 miles per second, & there are 525,600 is second in a year. 525,600 × 186282 = 97,909,818,200
light travels 5,878,630,000,000 miles in a year.
The distance of one light year, in light years, is exactly 1.
A light year is a measure of distance, not time. A light year is the distance that light will travel in one year. One light second is 186,000 miles. A light year is a measure of distance, not time. A light year is the distance that light will travel in one year. One light second is 186,000 miles.
4.27 light year = 2.51011942 × 1013 miles