Missing The solar system once had five giant gaseous planets rather than the four it has today. That's the conclusion from a computer simulation of the solar system's evolution, which suggests the ...

More than 7 billion miles away from the sun, out on the far reaches of the solar system, astronomers have spotted a planet-like object they’ve never seen before, and they’ve nicknamed it Biden.

A rogue star may explain why the outer solar system is so odd. Scientists have a new explanation for Pluto's tilted orbit and other idiosyncrasies.