How far is a light-year in miles?

I get asked this question A LOT when I give my “Magic of Photography” talk, so I thought I’d put the answer to this one up on my site.

Light travels at 186,000 miles per second, so all we need to do is multiply 186,000 by the number of seconds in a year and we’ll get the answer.

186,000 = 1.86 x 105

Seconds in a year = 365 x 24 x 3,600 = 3.15 x 107

Multiply the two together to get the number of miles in a light-year:

3.15 x 1.86 x 1012 = 5.9 x 1012 miles or nearly 6 x 1012 miles.

So the answer to the question is – there are 6 x 1012 miles in a light year.

Let’s go a little futher – how long would it take us to get the nearest star – Proxima Centauri which is 4.2 light-years away – if we travelled at a speed of a million miles a day (nearly 42,000 miles an hour)?

Answer – about 69,000 years!!

Space is BIG, REALLY BIG, you might think it’s a long walk down to the local supermarket but …………………..

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