Solar system


I like to start by finding out how much my students know about the movement of the stars, planets and moon, some seem to know very little (especially at 0800). They know how the sun moves but many don't know that the moon doesn't rise at the same time each day or that the planets wander.

Proving r3 ∝ T2 is a good bit of revision / application of Newton's laws.

There are some excellent simulations showing how everything moves and why it looks like it does from the Earth. I always like to build the solar system in Interactive Physics and make one of the planets the centre to show how the orbital motion gives rise to the planetary wander viewed from the Earth.


  • A lot of astrophysics is based on the assumption that what happens here happens out there, is this reasonable? What choice do we have but to make this assumption?
  • The story of Galileo and his conflict with the church is an interesting TOK issue.
  • Why were ancient civilisations so interested in the movement of the planets?


Intro to Astrophysics

Intro to Astrophysics answers

Text Book

Page 332 - 338


Problems 1 - 4



Screenshots of Chris' board


Phet solar system

This is a simple simulation showing the way the planets orbit the sun. You can also add a moon or simulate a sling shot but if you want more control then you need to set up your own sim in interactive physics or algodoo. See section on orbits.

Phases of the moon

This is one of a series of great flash animations from the university of Nebraska-Lincoln, since they are flash animations rather than Java applets they can easily be offloaded and run off-line. This one shows how the phases of the moon can be explained in terms of the orbits of the moon around the earth and the earth around the sun.

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