From a shrinking Mercury to Venus’s runaway greenhouse nightmare, the inner solar system is a story of extremes. This video ...

The four rocky worlds closest to the sun share a common ancestry but have followed radically different paths. Mercury is still shrinking as its interior cools. Venus traps so much heat that its ...

Scientists have seemingly settled long-standing arguments about whether the components of Earth originated from the inner or outer Solar System.

It’s not every day you get a chance to spot multiple planets with the naked eye—but this month, you can. Venus and Mercury are both visible in the sky, offering a rare glimpse ...