What if the aliens are hiding from us? Hiding a whole planet is easier than you think.
Pluto is too small to be considered a planet anymore, but our solar system appears to have a new ninth planet.
Pluto was demoted to dwarf planet status, but it still has moons. This new moon, called P5 for now, is the fifth moon found orbiting Pluto.
You've heard about comets and asteroids in space. What is the different?
Exactly how much are we damaging the environment when we put up new buildings and expand our cities?
Why are the planets where they are instead of somewhere else?
Nowadays everybody knows there are nine planets in our solar system, but that information was hard won.
Yes, it's true, Earth has "love handles!" Learn more about Earth's bulge...
What is our earth's history? New research suggests that life on Earth has existed without interruption for longer than we thought.
It seems to be possible for planets in a stable solar system to somehow get off track and run into each other. Is our planet in danger?