These icy bodies orbit the sun just like the major planets, yet they follow their own rules, often traveling along elongated ...

A rare discovery beyond Neptune is forcing scientists to rethink early solar system dynamics and the forces that shaped ...

After studying thousands of computer simulations of the solar system, researchers at Rice University and the Planetary Science Institute think there’s a 40% chance an elusive “Planet Nine” or “Planet ...

Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously unknown world may be lurking in the outer reaches of the solar system. The ...

Ammonite was discovered using the Subaru Telescope in Hawaii, with follow-up confirmation from the Canada-France-Hawaii Telescope. Its orbit and size officially qualify it as a distant dwarf planet.

In the remote outer reaches of planetary systems, far beyond the orbit of known planets, enormous and mysterious worlds silently loop around their stars. Some drift as far as 10,000 times the distance ...

There may be a warp in the Kuiper Belt, possibly caused by “Planet Y” — a Mercury-to-Earth-sized world that orbits the sun way beyond the orbit of Neptune. Is there a mysterious “Planet Y” orbiting ...

LONDON — The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper's authors have ...

On03, NASA's Pioneer 10 spacecraft beams its last data transmission back to Earth. Pioneer 10 was NASA's first mission to the ...

The origin of super-Earths and sub-Neptunes has been revealed in a system of four young planets that are dramatically losing ...