Once the quirky underdog of our solar system, Pluto held planetary status until 2006, when it got a cosmic demotion that still stings space fans. Discovered in 1930, Pluto was the ninth planet for ...

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

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 ...

Sedna will make its closest approach to the Sun in 2076, giving us a rare opportunity to visit the planetoid before it drifts ...

It took over nine years for New Horizons to reach Pluto after blasting off atop an Atlas 5 rocket on Jan. 19, 2006. After ...

Over the past decade, researchers have been puzzling through Pluto’s mysteries. Meanwhile, the New Horizons probe heads for interstellar space.

A ninth planet the size of Neptune may be hidden in the far reaches of the solar system, but the evidence has left some ... less than 20 years after the previous ninth planet, Pluto, ...

The planets in order from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. If you include the ...

Pluto, the fourth ninth planet -- 11. Hidden secrets of the outer solar system -- 12. The plutinos -- 13. Is Pluto a planet? -- 14. Goldilocks -- Postscript. Current thoughts by other astronomers -- ...

How many dwarf planets are there in our solar system? The recent discovery of 2017 OF201 makes the tally anywhere between five and 18, plus hundreds of potentially undiscovered ones, depending on whom ...

Close stellar encounters could change the structure of our planetary system, potentially dooming Earth or other worlds to ...

Pluto is the tiniest planet in our solar system with a diameter of roughly 2,377 kilometers, making it even smaller than our ...