The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

Wolf 359’s extreme radiation and frequent X-ray flares make life-sustaining atmospheres on nearby planets highly unlikely, ...

"With an orbital period of 570 days, it is a relatively cold gas giant planet," said Guðmundur Stefánsson of the University ...

The zodiacal light shines in the evening as the Moon reaches Last Quarter and skims past Spica and Antares in the sky this ...

Does our Solar System have 9 planets or only 8? Astronomers have gone back and forth on that a lot, with Pluto now being classified as a dwarf planet. However, out beyond Neptune there could be ...

Why is Pluto no longer a planet? Discover the real reason behind Pluto’s reclassification as a dwarf planet and the science that led to this change.

As the gatekeepers to the Kuiper Belt, Charon and Pluto are a unique double dwarf planet system ... Christy had been imaging Pluto with the USNO's 1.5-meter (4.9-foot) telescope.

In 2006, the International Astronomical Union (IAS) reclassified Pluto as a dwarf planet. That decision came several years after discovering the Kuiper Belt, a ring of icy and rocky objects 2.8 ...

An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit before shoving four of the solar system's planets onto a different course.

In August 2006, the International Astronomical Union made the controversial, but correct, decision to demote Pluto from its ...

The ESA’s Gaia mission mapped the positions and velocities of stars with extreme precision by measuring about one billion ...