Real castles aren’t this old. And the background galaxy is even older. Looking a bit like an alien castle, the pictured rock spires are called hoodoos and are likely millions […]

What color is the Moon? It depends on the night. Outside of the Earth’s atmosphere, the dark Moon, which shines by reflected sunlight, appears a magnificently brown-tinged gray. Viewed from […]

An almost full moon on April 15 brought these luminous apparitions to a northern spring night over Alberta Canada. On that night, bright moonlight refracted and reflected by hexagonal ice […]

There’s a black hole at the center of the Milky Way. Stars are observed to orbit a very massive and compact object there known as Sgr A* (say “sadge-ay-star”). But […]

The massive stars of NGC 346 are short lived, but very energetic. The star cluster is embedded in the largest star forming region in the Small Magellanic Cloud, some 210,000 […]

Albert Einstein’s general theory of relativity, published over 100 years ago, predicted the phenomenon of gravitational lensing. And that’s what gives these distant galaxies such a whimsical appearance, seen through […]

Nebulas are perhaps as famous for being identified with familiar shapes as perhaps cats are for getting into trouble. Still, no known cat could have created the vast Cat’s Paw […]

What’s that passing in front of the Sun? It looks like a moon, but it can’t be Earth’s Moon, because it isn’t round. It’s the Martian moon Phobos. The featured […]

Most galaxies don’t have any rings — why does this galaxy have two? To begin, the bright band near NGC 1512’s center is a nuclear ring, a ring that surrounds […]

On certain dates in February, an elusive firefall can be spotted at sunset in Yosemite National Park, when water flows, the weather cooperates and the direction to the setting Sun […]