Space 01
How a dip in starlight reveals an exoplanet’s size
Infer a planet-to-star radius ratio from a transit light curve, compare Earth and Jupiter signals, and explore why grazing transits need more care.
planets
Space 02
Why planets lose atmospheres: gravity, temperature and molecular speed
Compare escape velocity with a thermal gas distribution, and learn why a fast molecular tail does not directly give an atmospheric lifetime.
Space 03
Why planets seem to move backward: retrograde motion explained
Use Earth’s moving viewpoint to explain Mars, Mercury and Venus retrograde motion, with a worked synodic-period example.