Astronomers are hunting for evidence of a mysterious ninth planet beyond Neptune. This documentary uncovers the clues, the science, and what discovery could mean for our solar system.

The James Webb Space Telescope's Near-Infrared camera (NIRCam) captured stunning imagery of Neptune, its rings and moons. It is the "clearest view of this peculiar planet’s rings in more than 30 years ...

Astronomers used a telescope in Hawaii to find a new object on the outer edges of our solar system, helping to fuel evidence of a long-standing theory about Planet Nine, or Planet X. For years, ...

Because the solar system's contents formed from a disk around the sun, we would expect the orbits of everything orbiting the sun to keep relatively close to the plane of that disk. However, some don’t ...

Neptune, long believed to be dark blue, is actually very pale like Uranus, scientists say. They used modern telescopes to re-assess artificially enhanced images taken by NASA's Voyager 2 probe. We can ...

In pictures of the farthest planets from the sun, Uranus looks like a pale-green orb, while Neptune usually looks much bluer. A new analysis revealed their true colors. Here's NPR's Nell ...