It must have cleared all other celestial bodies, except its own moons, from its orbit.

In the time Pluto was found, classified as a planet and reclassified as a dwarf planet, it has not completed one orbit. One ...

After a decade-long search, some scientists say a growing number of clues point to the existence of a hidden planet in the Kuiper Belt beyond Neptune — and they may soon have the opportunity to find ...

than any of the planets in the outer solar system. Nevertheless, because it orbited the Sun like a planet, it was classified as a planet and named Pluto, after the god of outer darkness in Roman ...

Our solar system has eight planets but in recent years, astronomers have theorised there could well be a ninth planet that's hiding in our solar system we've not been able to see yet.

We know about Pluto. But we don’t really know ... ideas about how the migration of the giant planets sculpted the early solar system. “We think the Kuiper belt was a lot more massive early ...

it has as rich geology as any of its planetary siblings in the solar system A color-enhanced photo of Pluto that was captured by the New Horizons spacecraft in 2015 NASA / Johns Hopkins University ...

NASA has given a new lease of life to its New Horizons mission, which in 2015 got the first-ever close-ups images of dwarf planet ... and its solar wind at the very edges of our solar system.

Are there hidden planets in our solar system? New technologies, like the powerful Rubin Observatory, brings us closer to ...

Aside from the solar system once again having nine planets—which it had before Pluto’s demotion in 2006—the discovery of a distant Earth-mass planet would have profound implications for ...

The solar system has nine planets, but in 2006 the International Astronomical Union declared Pluto a dwarf planet, making the ...