The inner solar system is home to four rocky worlds that formed under the intense heat of the young Sun. This video explores Mercury, the scarred planet that is slowly shrinking; Venus, where a ...

Forbes contributors publish independent expert analyses and insights. An award-winning reporter writing about stargazing and the night sky. The solar system suddenly has a new member. A new object ...

Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously unknown world may be lurking in the outer reaches of the solar system. The ...