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 August 24, 2006, our solar system lost a planet. It wasn't by cataclysmic destruction, but rather by the vote of the International Astronomical Union, which declared that Pluto, considered the ...

Researchers have found a candidate for the hypothetical Planet Nine, which could be an undiscovered giant planet way out in our solar system. However, as with all ninth planet research, the new ...

An artist's illustration of a possible ninth planet in our solar system, hovering at the edge of our solar system. Neptune's orbit is shown as a bright ring around the Sun. Scientists in Taiwan ...

Caltech professor Mike Brown (L) and assistant professor Konstanin Batygin have been working together to investigate distant objects in our solar system for more than a year and a half. The two ...

Astronomers have been scouring the outer solar system for signs of a hypothetical ninth planet for almost a decade, without success. However, we may finally be on the cusp of finding it, experts say.