The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

Extrasolar planets contextualise the Solar System among a large number of planetary systems with very different properties. Many extrasolar planets show characteristics which are not realised in the ...

Mike Brown, an astronomer at Caltech, said: "It's really difficult to explain the solar system without Planet Nine but there's no way to be 100 per cent sure [it exists] until you see it." ...

There may be an undiscovered planet in the outer solar system whose presence is revealed by the strange orbit of objects beyond the eighth planet Neptune. The tantalizing prospect of a ninth ...

The night sky recently played host to a truly extraordinary event: a planetary parade unlike any seen by this generation. From late January to early February 2025, several planets in our solar system ...