He called this hypothetical world "Planet X." "In some ways, Pluto's more of a planet than some of the other established planets, like Mercury." ...

Mercury will join Pluto in an empowering and revelatory sextile, which could lead to powerful breakthroughs in communication ...

It takes Pluto slightly over 248 Earth years to orbit the sun, which means that on March 23, 2178, one Plutonian year will have elapsed since the dwarf planet was first spotted, on Feb. 18 ...

If you answered "Pluto's planethood," your grasp of the astronomical is excellent. Feb. 18 marks the 95th anniversary of the discovery of our outermost planet-not-planet. Here's what to know about ...

The ringed gas giant Saturn has officially replaced Jupiter as the planet in our solar system with the most moons. The ...

Pluto was discovered at Lowell Observatory in Flagstaff, Arizona in 1930 and was considered our ninth planet until 2006. The International Astronomical Union reclassified Pluto as a dwarf planet ...

Pluto was the little planet that could — until it couldn’t. Discovered in 1930 at Lowell Observatory in Flagstaff, Arizona, Pluto was hailed as the ninth planet in our solar system.

Pluto will mark a birthday of sorts on March 23, 2178. No one is likely to be there to celebrate it, of course. Even if humanity is a multi-planet species by then, it would be a decided challenge to ...

Back in 2006 our Solar System lost a planet, not because it disappeared, but because it was reclassified. Pluto, now considered a dwarf planet, failed one of the three tests the International ...

The cosmos is filled with wonders yet to be discovered. One of the latest mysteries captivating scientists and space ...