Earth has a newly-discovered neighbor in the solar system. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit ...

The planet Neptune wobbled in its orbit around the Sun. That could only mean one thing, astronomers said: There was a ninth planet out there, somewhere, lurking in the fringes of the solar system.

On Aug. 24, 2006, the International Astronomical Union (IAU) decided that Pluto wasn't a planet anymore. Instead, Pluto is now officially classified as a dwarf planet along with four other confirmed ...

It's not exactly news to say that Pluto is no longer considered a planet. That made headlines almost 20 years ago. But what if I told you that decision at the time was controversial, not just among ...

Several Johns Hopkins University astronomers described a decision Thursday to strip Pluto of its planetary status as a “muddled” ruling that is unlikely to settle ongoing debates over how to define a ...

A possible new dwarf planet described as "Pluto's cousin" has been found at the edge of the solar system, so far away that it takes around 25,000 years to complete one orbit around the Sun.

Before Pluto was discovered, it was predicted. Astronomers had observed that massive objects can affect the orbits of their neighbors and, after seeing deviations in the orbits of Uranus and Neptune, ...

Using NASA’s Hubble Space Telescope to view the ninth planet in our solar system, astronomers discovered Pluto may have not one, but three moons. If confirmed, the discovery of the two new moons could ...

WASHINGTON, May 30 (Reuters) - Scientists have identified an object about 435 miles (700 km) wide inhabiting the frigid outer reaches of our solar system that might qualify as a dwarf planet, spotting ...

In the Feb. 23 issue of the journal Nature, a team led by Dr. Hal Weaver of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., describes its discovery of two new moons ...

A possible cousin of Pluto seems to be circling the far reaches of the solar system. The dwarf planet candidate 2017 OF201 travels in a superwide orbit, with the sun relatively near one end of its ...