Level 5: Measuring the sky

Space and time · level 5 of 8 · rough age 12-13 (a guide for parents; anyone can start anywhere)

Nobody has stretched a tape measure to the Sun. Every distance in space was worked out from angles, timing and a little geometry. This level measures angles in the sky, turns them into sizes and distances, and ends with how big Mars looks from Earth, and why it changes so much.

Lesson	You will be able to
Angles in the sky	Use degrees, arcminutes and arcseconds to describe the sky
Angular size	Link how big something looks to its real size and distance
Parallax	Find a distance from the shift seen from two places
The astronomical unit	Use Kepler's third law to find planet distances in au
Light-minutes and light-years	Measure distance by the time light takes
How big Mars looks	Work out the size of Mars in the sky, and why it changes

Previous: Level 4: Clocks on Mars · Next: Level 6: Light delay · Space and time topic page