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### Length of a Light-Year

```
Date: 1/31/96 at 12:5:15
From: Anonymous
Subject: Distance Conversions

How far is a light-year in miles or kilometers?
```

```
Date: 6/15/96 at 9:11:7
From: Doctor Robert
Subject: Re: Distance Conversions

A light-year is the DISTANCE that light travels in a year.
The speed of light has been measured to be approximately
186,000 miles per second. Light then travels
(186000 mi/sec)(60 sec/min)(60 min/hr)(24 hr/day)(365 day/yr)
which is approximately 5,870,000,000,000 miles in a year!

That many miles is one light-year.

-Doctor Robert,  The Math Forum
```

```
Date: 04/21/2002 at 02:06:47
From: Anonymous
Subject: A light-year

What is a light-year?
```

```
Date: 04/21/2002 at 08:30:18
From: Doctor Jerry
Subject: Re: A light-year

Hi,

A light-year is a measure of distance.  It is the distance light will
travel in one  year.

1 light year is about 9.5 * 10^{15} meters.

You can calculate this as follows: light travels at a speed of
300,000,000 meters per second. By multiplying the speed of light by
the number of seconds in one year (which is about 365.25*24*60*60),
we find 9.5 * 10^{15} meters.  This is

9 500 000 000 000 000 meters.

- Doctor Jerry, The Math Forum

```
Associated Topics:
High School Definitions
Middle School Definitions
Middle School Terms/Units of Measurement

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