True planets, dwarf planets, and exoplanets--what's the difference? Learn the three rules scientists use to decide what makes something a planet. Discover how the search continues …
Find out how far away the Moon is, why it seems to change shape, and who the first person was to walk on the Moon. Notes to caregivers and teachers provide question prompts to …
Take an incredible look at the planet Mars and its place in our solar system. Find out how it compares to Earth and learn more about its future exploration. Notes to caregivers and …