The mysterious Oort cloud is the source of many of our solar system's comets, but astronomers still have no idea what it ...

Did you know our solar system might have had an extra planet? Scientists believe a mysterious ninth planet once existed but ...

Planet demographics reveal a puzzling lack of worlds in a certain size range throughout the galaxy F or centuries our solar ...

To see the parade, find a dark place with a clear view of the western horizon at nightfall. Mercury and Saturn will be low in the sky, brushing past each other in the fading glow of the evening sun, ...

In February 2025, all seven of our planetary neighbors will be visible from Earth. So what does such a planetary alignment ...

Astronomers for the first time have deciphered the three-dimensional structure of the atmosphere of a planet beyond our solar ...

Sure, they’re particles and rocks, but they’re still a fascinatingly long way from home. Alpha Centauri is the star system ...

Feb. 18 marks the 95th anniversary of the discovery of our outermost planet-not-planet. Here's what to know about the short ...

But turning our nine-planet solar system into eight just earned Pluto more fans. This year also marks the 10th anniversary of Pluto's first dedicated flyby mission. NASA’s New Horizons spacecraft ...

A shell of icy objects at the edge of the solar system known as the Oort cloud has a pair of spiral arms that resemble a miniature galaxy, new research suggests.

Mercury has a rocky surface when, facing the sun, can reach highs of 800 degrees while overnight lows could reach minus 290 ...

Saturn, Venus, Neptune, Uranus, Jupiter, Mars and Mercury will be visible in an uncommon planetary alignment this month.