5  Summary of Week 4

This week you’ve learned about transiting planets both inside and outside the Solar System. You have seen how transits can be used to find and measure the size of exoplanets. You’ve learned how the transit depth is measured, and how that depends on the relative sizes of the star and the planet in question.

You should now be able to:

• state which planets in the Solar System are observed to transit the Sun, and explain why
• outline how transits can be used to identify exoplanets and measure the size of stars and planets
• state the relationship between radius and cross-sectional area for a sphere
• show you understand the size ratio between the Sun, Jupiter and Earth
• describe the relationship between transit depth and the ratio of radii of the planet and star (R _p /R _star)².

You are now halfway through the course. The Open University would really appreciate your feedback and suggestions for future improvement in our optional end-of-course survey, which you will also have an opportunity to complete at the end of Week 8. Participation will be completely confidential and we will not pass on your details to others.

Next week you will be learning more about how to measure the properties of individual planets using the transit technique and the radial velocity technique that you learned about in Week 3.

You can now go to Week 5.