This icy world, temporarily named 2017 OF201, could be a distant cousin of Pluto — and scientists mean "distant" quite ...

Astronomers have discovered a mysterious dwarf planet, 2017 OF201, far beyond Pluto. This discovery challenges existing ...

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

Pluto’s demotion ... a new planet hiding beyond Neptune. Two astronomers in Japan, Patryk Sofia Lykawka and Takashi Ito, claim there is a planet a little larger than Earth lurking in the Kuiper ...

New Horizon’s trajectory from Earth to Pluto and the mysterious 2014 MU69. The object is about a billion miles away from Pluto. Credits: NASA/JHUAPL/SwRI/Alex Parker In November the New Horizons ...

Scientists discovered an extremely distant object billions of miles beyond Pluto. The object has an orbit that hints at an even-farther-out “Super-Earth” or larger “Planet X” that could ...

It’s about 80 astronomical units away, meaning it’s 80 times farther from the sun than Earth, or about twice as far as Pluto ... says one of the outstanding mysteries swirling around these ...

The New Horizons spacecraft attempts to fly by a mysterious object known ... the first spectacular photos of Pluto, New Horizons is four billion miles from Earth, trying to achieve the most ...

"Planet X" might actually exist — and so might "Planet Y." At least two planets larger than Earth likely lurk in the dark depths of space far beyond Pluto, just waiting to be discovered, a new ...