What is a Light Year?

The Andromeda Galaxy           2.5 million light years from Earth

Over the last set of blogs, I have described the basic format of my telescope used to capture deep sky and solar system targets from my garden in Kingswinford.

Let’s take a quick detour from my set up! I want to share what really fascinates me with our universe and why I love this hobby so much!

When we look up at the night sky, we are looking at stars that are a long distance away from us, galaxies even further! The distances are so vast they are measured and quoted as “light years”.

So, what is a light year?

Light travels at an incredible speed of 186,000 miles per second.

The moon is orbiting the Earth at 250,000 miles. So, the time taken for light to travel from the Earth to the moon is 1.3 seconds.

So to calculate a light year :-

  • A light minute is 186,000 x 60 seconds = 11,160,000 miles
  • A light hour is 11,160,000 x 60 minutes = 669,600,000 miles
  • A light day is 669,600,000 x 24 hours = 16,070,400,000 miles
  • A light year is 16,070,400 x 365.25 days = 5,869,713,600,000 miles (5.8 trillion miles!)

The distance to our nearest star Alpha Centauri –

4.4 x 5,869,713,600,000   = 25,826,739,840,000 miles….A long, long, way!

I hope that quick explanation made sense!

If you have any questions, do get in touch!

You can contact me by messaging me from my contact page by following this link: Click here.

Many thanks – check back soon,



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