For decades, our solar system was thought to have nine planets, with Pluto considered the smallest and farthest. But in 2006, ...

Almost 20 years after Pluto was infamously downgraded from its status as a planet, scientists now believe they have ...

Astronomers find evidence of a possible ninth planet beyond Neptune, reigniting the debate about the formation of the Solar ...

There’s a new object in the distant reaches of our solar system, and it might just offer clues to a long-standing cosmic ...

Astronomers may have found a candidate for Planet Nine. This planet is beyond Neptune. The finding could be the first evidence of the theorized Planet ...

Scientists hunting for Planet Nine, an elusive planetary body that could change our understanding of the solar system, have found something. Planet X is a hypothetical planet seven times the mass ...

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the ...

U.S. astronomers hunting for "Planet Nine" have instead stumbled on what appears to be a new dwarf planet in the solar system's outer reaches.

The object is about 700 kilometres wide and lies nearly three times farther from Earth than Neptune. Its highly elongated ...

Our solar system may have a ninth planet after all ... to a celestial body that could be a possible candidate as "Planet Nine," according to a new paper, which has been accepted for publication ...

The small world was found during a search for the hypothetical Planet Nine, and astronomers say the next time it will reach ...