What if there’s a planet hiding in our solar system, 10 times larger than Earth? While this theory has yet to be confirmed, ...

For many of us, the idea of a solar system with just eight planets is a fundamental concept in science. However, since Pluto was reclassified as a dwarf planet in 2006, Neptune has stood as the last ...

If such a hidden object—sometimes whimsically called “Planet X”—exists, it would orbit at least 10 times farther from the sun than Neptune—too distant and too faint to have been spotted ...

Planet X has a long and storied history of non-existence. For about 130 years, astronomers have debated the existence of an additional planet or planets to explain discrepancies in the orbits of ...

Planet X, or Nibiru, is on a crash course with Earth, doomsayers believe — prophecies draw new focus with ‘Planet Nine’ discovery ...

If Planet X is out there, it’s really, really far away. Brown and Batygin’s educated guess as to where Planet X might be is based on the crooked orbits of 6 very distant objects.

The hunt for the hypothetical "Planet X" has been fruitless so far, but that doesn't mean astronomers are calling it off. A new analysis of data collected by NASA's Wide-Field Infrared Survey ...

Although the paper is certain to revive the search for Planet X, success is not certain: Previous surveys have failed to detect any Saturn-sized planets going out as far as 10,000 AU.

An artist's concept of Planet 9, sometimes referred to as Planet X. Planet 9 is a hypothesized ninth planet in our solar system. It is not about to kill us all.

And if Planet X — also sometimes called Planet Nine — exists, it’s way out there; it’s somewhere between 200 and 1,200 times the distance from the Sun to Earth.

Look, it’s Planet X, again. No, not the mythical dead star that’s supposed to appear in the sky in 2003 in 2012 on Sept. 23, 2017 last October in November on April 23 and herald the end of the ...

While searching for the mysterious Planet X that some astronomers believe lurks on the edge of our solar system, researchers instead found an extremely distant object they dubbed “the Goblin.” ...