Stargazing Guy

A light-year is a measure of distance – not time (or anything to do with Disney’s Toy Story).

It’s used to indicate the distance to stars and galaxies.

It’s the distance light travels in one year in a vacuum, which is about:

– 4.2465 light-years OR 5.88 trillion miles OR 9.46 trillion kilometres

Light travels at about:

186,282 miles per second OR 670.6 million miles per hour OR 299,792,458 metres per second

The light from the Sun takes about 8 minutes to reach Earth, because it is about:

93 million miles OR 150 million kilometres away.

The light from Proxima Centauri takes about 4.2465 years to reach Earth, becasue it is about:

4.2465 light-years OR 25 trillion miles OR 40 trillion kilometres away.

As you can see, the light-year is a very useful measure of distance for stars … not so good when it comes to galaxies (or other cosmological objects, such as quasars).

The Andromeda Galaxy , a similar shape but larger than our galaxy (the Milky Way Galaxy) is far, far away. It is:

2.5 million light-years OR 1.49 quadrillion miles OR 2.4 quadrillion kilometers

Credit:

https://www.esa.int/About_Us/ESAC/Proxima_Centauri_our_nearest_neighbour

https://www.nasa.gov/image-article/galaxy-next-door/

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PS: I love coffee. BuyMeACoffee, leave a message with a date and time and we can share it, remotely, at the same time, and think about the Cosmos.

In the meantime, take care of yourself and if you can, someone else, too, because as Adam Smith said, “we naturally desire not only to be loved but to be lovely”.

Remember, hope lives here.

Opening image source: https://www.explainxkcd.com/wiki/index.php/2897:_Light_Leap_Years

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