A new paper discusses the possible existence of an unseen planet in the outer solar system, the so-called "Planet X" or ...

Test your knowledge on our solar system, from the biggest and smallest planets to the behemoth mountain on Mars.

Learn how you can see bright Jupiter from Earth, helped by its massive size and banded, reflective cloud tops, in December's ...

A NASA Hubble Space Telescope observation program called OPAL (Outer Planet Atmospheres Legacy) obtains long-term baseline observations of Jupiter, Saturn, Uranus, and Neptune in order to understand ...

Weather permitting, Jupiter will not only be brighter than most other stars and planets in the evening sky, but will also be ...

If planet X exists, it is likely a gas giant similar to Neptune. NASA/Caltech/R. Hurt (IPAC), CC BY Our solar system is a particularly crowded place. Millions of objects move within it, whether they ...

It's an interesting thought experiment; while Borisov and 'Oumuamua were smaller objects, a more massive rogue planet joining our solar system could generate orbital chaos. It could potentially ...

In the next decade, researchers will start probing the atmosphere of planets as small as Earth and Venus orbiting nearby stars. But although these two solar system planets are similar in size and ...