(WHTM) – Our solar system has eight (was nine) planets and is roughly 4.571 billion years old. The planets in our solar system include Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune ...

"We were finding quite a few Earth-sized things, but not very much smaller than that," said Thomas Barclay, an astrophysicist at NASA's Goddard Space Flight Center and first author of the 2013 paper ...

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SEATTLE – NASA has discovered the smallest planet ever seen beyond our solar system – a rocky world just 1.4 times larger than Earth – using its planet-hunting Kepler observatory. The planet, called ...

Astronomers from Princeton and other institutions have discovered the smallest planet found outside of our solar system using a technique that researchers believe will uncover others that potentially ...

Mercury, the smallest planet in our solar system, has captivated scientists due to its extreme temperatures, dense iron-rich core, magnetic field, and distinctive geological features. Recent research ...

A large asteroid could be reclassified as a dwarf planet -- which could make it the smallest in the solar system -- after new research revealed it's shape, astronomers said on Monday. A large asteroid ...

Astronomers have detected the smallest rogue planet in our Milky Way galaxy, and it's between the sizes of Mars and Earth. Rogue planets are free-floating planets that don't orbit stars. Astronomers ...

A spacecraft operated by the European Space Agency and the Japan Aerospace Exploration Agency has made its final flyby of Mercury, as scientists now work to guide BepiColombo into the planet’s orbit.

NASA bragged Tuesday that its Kepler Space Telescope had discovered the two smallest planets ever found orbiting a distant star, but a UA astronomer and colleagues may have discovered even smaller ...

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 ...