Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Many Americans grew up with this as the definitive planetary lineup and created clever mnemonic devices to memorize them in ...

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Clyde Tombaugh didn't set out to discover Pluto when he sent his sketches of the night sky to Lowell Observatory in Flagstaff ...

This story is part of Short Wave's series Space Camp about all the weird, wonderful things happening in the universe. Check out the rest of the series. If you were born in the last century you might ...

It’s been 18 years since Pluto’s celestial status was called into question—yet the matter seems far from settled. We asked experts from both sides to make their case. This 2015 NASA image of Pluto ...

Editor’s note: A version of this story originally appeared in Astronomy’s 2007 special issue 50 Greatest Mysteries of the Universe. For a more recent discussion of Pluto’s planethood, see “An ...

A new formation theory for Pluto's moon Charon could explain why Pluto is geologically active. Illustration incorporates NASA New Horizons terrain imagery. Pluto — demoted to dwarf planets status in ...

Pluto may have lost its status as a full-fledged planet in 2006, but that doesn't mean it's a joke of a world this April Fools' Day and the folks behind Pluto TV want to make that clear. On April 1, ...

The debate over Pluto’s planetary status has been ongoing since its reclassification as a “dwarf planet” in 2006 by the International Astronomical Union (IAU). Recent discussions and new scientific ...

You know what a planet is, right? A big round thing that orbits a star. Uh, not so fast. You know what a planet is, right? A big round thing that orbits a star. Uh, not so fast. The surprisingly ...

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Small but mighty Pluto is connected to destruction, subversion, depth, intensity, primal urges, the taboo and much more. NY Post photo composite Come on down to the underworld, folks — we’re talking ...