There have been questions about a mysterious ninth planet in our solar system for nearly a decade. Pluto was unseated as number nine in 2006. Now, a group of international researchers say they may ...

Pluto was reclassified as a dwarf planet in 2006. Our solar system may have a ninth planet after all, researchers say. The possibility that an additional planet may be hidden far into the solar system ...

On the heels of a year that brought a dazzling green comet, a rare sunrise eclipse, peak planet viewing, an interstellar ...

There's a new object in the distant reaches of our solar system, and it might just offer clues to a long-standing cosmic mystery. Astronomers have cataloged a frozen minor planet called 2017 OF201, ...

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 dubbed ...

Jupiter is already the biggest planet by far in our solar system, but new research suggests it was somehow once even larger than it is now. Twice as large, in fact. To put that into context, those ...

A lucky alignment of space- and ground-based telescopes has enabled researchers to nail down the mass of a rogue planet for the first time. Unlike worlds in our Solar System, rogue planets do not ...

The internet has been abuzz with the possibility of sky watchers seeing a “smiley face” in the eastern sky above the horizon on Friday morning before dawn. Just so you know, some of the graphics used ...