Moons of our Solar System
Moons of our Solar System

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Moons of our Solar System

Week 2: Looking at moons


Like planets, moons can have an internal layered structure: a core, mantle and crust. At Jupiter and beyond, the outer part of each moon is ice that behaves like rock. How do moons get their names?

Jess gives you a heads up on what to expect this week.

Download this video clip.Video player: moons_1_vid016.mp4
Skip transcript


Hi there. Well done for getting to Week 2. Last week we had a first look into moons and their orbits. I think my favourite part was the ‘Waltz around Saturn’ - the video of Saturn’s moons set to music. Much of my work is focused on laboratory analysis of samples, but every now and then it’s good to be reminded just how simply beautiful moons can be.
This week you’ll discover what moons are made of and how - like a planet - they can have an internal layered structure. By which I mean a core, mantle and a crust. You’ll find that moons in the outer Solar System, at Jupiter and beyond, tend to contain a higher proportion of ice and the ice is so cold, it behaves essentially like rock.
You’ll also discover that ice isn’t just frozen water. It can be the frozen form of substances that are more familiar to us on Earth as gases, such as methane and carbon dioxide. Further from the Sun the cocktail of ices on the moons gets richer, which is another reason why this sort of ice behaves like rock does within the Earth.
Then we’ll look at craters. Craters are really interesting. On our Moon - like on other moons - we’ve learned that they have been formed as the result of large meteorite and comet impacts. In the final hour this week we’ll see how impacts occurring on the Moon can actually be observed, and what these observations tell us. We’ve built a simulator - actually a bit of a game, that allows you to work out the size of a crater that would be formed on different moons by particular impactors. See you next week.
End transcript
Copy this transcript to the clipboard
Print this transcript
Interactive feature not available in single page view (see it in standard view).

By the end of this week, you should be able to:

  • recognise the structure of a moon and what it’s made of
  • understand the significance of ice, and its different forms, in the moons of the outer solar system
  • understand how a moon’s surface is altered by comet or meteorite impact.

If you wanted to look into this further, you might find the following links of interest:

  • 10 things you should know about moons [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] In December 2015, Oxford University Press invited David Rothery to describe ten key points about moons on video. Here is the result. It sums up much of week 1, and introduces a few things that have not yet come up.
  • Planets and moons chat recording. The recording our of live webcast made on Weds 9 March 2016, 19:30-20:15 GMT can be viewed at this link (you will see the video stream only, not the ‘voting widgets’)

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus