Why is there no air on the Moon?

I was asked two questions a few weeks ago and I’ve been pondering the answers ever since: Why is there no air on the Moon? And how does our air stay on Earth?

Moon Day 12
Moon Day 12

These fantastic questions got me thinking about my answers to What is air made of? and Why are there no trees on the Moon?. But neither of those quite answered these new questions. So, after much deliberation, here’s my answer!

The planet Earth is surrounded by something called an ‘atmosphere’. An atmosphere is the name scientists give to the gases that surround a planet (or a similar body, like a moon). The Earth’s atmosphere is mostly made up of nitrogen, oxygen and water vapour. I wrote about the Earth’s atmosphere in my answer to How high is the sky?.

The gases in an atmosphere are held in place next to that planet or moon by something called ‘gravity‘. Gravity is what keeps things together in space – like stars and planets. It’s also the reason that things fall back down to the ground when you throw them up into the air. Gravity keeps us from falling off the Earth and it keeps the Earth orbiting around the Sun. We can’t see it or smell it or taste it and we can’t really feel it, even though it’s pressing us onto the Earth’s surface all the time!

So gravity keeps the gases in the Earth’s atmopshere next to our planet and stops them from disappearing off into space.

The Moon has a very thin atmosphere, which is made up of different gases to the atmosphere on Earth. It isn’t made of the gases in air, so when astronauts visit the Moon, they have to take air with them so that they can breathe!

If you enjoyed this post, you might also like to read How bright does the Moon shine?

And, once again, I’d like to thank my friend Alex for permission to use his amazing Moon photo in this post.

4 thoughts on “Why is there no air on the Moon?

  1. Kathryn Grace December 7, 2016 / 8:13 pm

    Oh, I’m delighted to find you, thanks to your feature on WordPress’s The Daily Post. What an amazing photograph of the moon, from an angle I don’t recall ever seeing. It looks like a moldy naval orange. I know your site will come in handy when I’m talking with my grandchildren and questions like these come up. I just hope I can remember the answers, or find them fast if I haven’t already seen them, when they ask! I’m not ashamed to Google for answers. I’ve been friends with plenty of reference librarians in my lifetime and strongly believe in “looking stuff up.”

    Liked by 1 person

    • kturton December 9, 2016 / 9:09 pm

      Thank you! I’m glad you enjoyed this post. The photo was taken by my friend and he very kindly allows me to use it on my blog. Encourage your grandchildren to keep asking amazing questions and, hopefully, I can help with some of the answers 🙂

      Liked by 1 person

  2. Anna December 10, 2016 / 7:55 pm

    I have a general science degree. My job is unrelated. Recently, I have been missing science! Most likely due to the TV series, The Flash, which involves physics. This blog has inspired me to consider creating a YouTube channel as an outlet for my science-y side 🙂 I look forward to reading your other posts.

    Like

    • kturton December 10, 2016 / 8:38 pm

      I’m glad you’re enjoying the blog. It is lovely to hear that it has inspired you to create a YouTube channel 🙂

      Liked by 1 person

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