Clyde Tombaugh discovered Pluto in 1930 at Lowell Observatory in Flagstaff. Here's how Pluto won - and lost - its planetary ...

“New Horizons shattered a major paradigm of planetary science,” says Alan Stern, the mission’s principal investigator. “Pluto turns out to have as much complexity as Mars or Earth, so much so that I ...

For decades, it captivated imaginations with its icy surface and distant orbit beyond Neptune. But in 2006, Pluto’s planetary reign came to an end when the International Astronomical Union ...

The IAU defends the definition based on Pluto’s orbit. Unlike other planets that have a more or less circular, equatorial orbit around the sun, Pluto’s is sharply inclined and highly ...

Pluto did not meet all three criteria the IAU determined were necessary to be considered a planet: The body must orbit its host star, just as Earth and Jupiter orbit the sun. It is large enough to ...

An amateur astronomer discovered Pluto 95 years ago today. The former planet will complete an orbit in another 153 years. On February 18, 1930, just two weeks after his 24th birthday, Clyde ...

Pluto was discovered 95 years ago on Feb. 18 ... the Lowell Observatory said. The body must orbit its host star, just as Earth and Jupiter orbit the sun. It is large enough to be mostly round.

Still that date will be one to circle on cosmic calendars. 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 ...

In 2006, astronomers reclassified Pluto as a dwarf planet when the International Astronomical Union voted to redefine what a planet is. The new definition requires that a planet: orbit the sun ...

It must orbit the sun. It must have enough mass to force its shape into a sphere. It must clear competing bodies and materials out of its orbital path. Because tiny Pluto hasn't cleared the Kuiper ...