Earth has a newly-discovered neighbor in the solar system. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit ...

What was discovered in Flagstaff, Arizona, and killed off in Prague? If you answered "Pluto's planethood," your grasp of the astronomical is excellent. Feb. 18 marks the 95th anniversary of the ...

Journey beyond the asteroid belt to explore the solar system's majestic giants and mysterious outer reaches. We break down ...

Pluto, discovered in 1930, was once considered the ninth planet in our solar system. In 2006, the International Astronomical Union reclassified Pluto as a dwarf planet because it doesn't meet all the ...

Lowell Observatory's sixth annual "I Heart Pluto Festival" will honor the remote icy world that was reclassified as a dwarf planet in 2006 When you purchase through links on our site, we may earn an ...

The planet Neptune wobbled in its orbit around the Sun. That could only mean one thing, astronomers said: There was a ninth planet out there, somewhere, lurking in the fringes of the solar system.

A composite image showing the five dwarf planets recognized by the International Astronomical Union, plus the newly discovered trans-Neptunian object 2017 OF201. The TNO is potentially large enough to ...

NASA's Hubble Space Telescope detected material from a Pluto-like body spiraling into a white dwarf star 260 light-years away from Earth. Credit: NASA / JPL-Caltech / Tim Pyle illustration For the ...

(Correction: An earlier version of this story misstated how far Pluto is from the sun. The correct number is 3.7 billion miles.) What was discovered in Flagstaff, Arizona, and killed off in Prague? If ...