Mercury is the smallest planet in our solar system. Explore its size, extreme temperatures, core structure, and comparison with Pluto.

In a new study, a team of astrophysicists, including two researchers at CU Boulder, have discovered a small and rocky world orbiting a star far from Earth—similar to our own planet, perhaps, but much ...

Studying the orbits of thousands of exoplanets shows that large planets tend to have elliptical orbits, while smaller planets tend to have more circular orbits. This split coincides with several other ...