The event horizon of a nonspinning billion-solar-mass back hole has a radius of 1.8 billion miles — the distance of Uranus from the Sun.

Earth's satellite sits close to the Red Planet in the predawn sky, before passing both Mars and Jupiter later in the day.

Venus’ reign is coming to an end as Mars and Jupiter enter the scene and the Moon occults Regulus in the southern sky this ...

Stunning face-on spiral M74 is visible after dark this evening, showing off its bright nucleus and fainter asymmetrical arms ...

Our satellite stands in Cancer the Crab, not far from M44 and ready to approach western Leo to pass the planets there.

Our satellite passes several planets while Venus meets Spica in a close conjunction and spooky season culminates in the sky ...

October’s bright Full Moon offers an excellent observing target, allowing you to trace the rays thrown out by ancient impacts ...

This crescent-shaped cluster shines in northern Cassiopeia, visible all night long as the stars wheel around the North ...

The Red Planet reaches the border of Cancer and Leo; tomorrow it will have crossed the line into the Lion, sharing it with ...

A 1,100-mile-long ice cloud forms near the martian volcano Arsia Mons every morning. New simulations suggest it’s built by a ...

The Moon passes 5° north of Uranus at 6 A.M. EDT this morning. You’ll find our satellite hanging above the Pleiades (M45) in ...