Captured last week after sunset on a Chilean autumn night, an exceptional airglow floods this allsky view from Las Campanas Observatory. The airglow was so intense it diminished parts of […]

This image is not blurry. It shows in clear detail that the largest satellite galaxy to our Milky Way, the Large Cloud of Magellan (LMC), rotates. First determined with Hubble, […]

Four hundred years ago today (May 15, 1618) Johannes Kepler discovered the simple mathematical rule governing the orbits of the solar system’s planets, now recognized as Kepler’s Third Law of […]

Why does a volcanic eruption sometimes create lightning? Pictured above, the Sakurajima volcano in southern Japan was caught erupting in 2013 January. Magma bubbles so hot they glowed shot away […]

This pretty cosmic cloud lies some 1,500 light-years away, it shape and color reminiscent of a blue robin’s egg. It spans about 3 light-years, nested securely within the boundaries of […]

Large galaxies grow by eating small ones. Even our own galaxy practices galactic cannibalism, absorbing small galaxies that get too close and are captured by the Milky Way’s gravity. In […]

How was the unusual Red Rectangle nebula created? At the nebula’s center is an aging binary star system that surely powers the nebula but does not, as yet, explain its […]

Why is there a large boulder near the center of Tycho’s peak? Tycho crater on the Moon is one of the easiest features to see, visible even to the unaided […]

Stickney Crater, the largest crater on the martian moon Phobos, is named for Chloe Angeline Stickney Hall, mathematician and wife of astronomer Asaph Hall. Asaph Hall discovered both the Red […]

Big, beautiful spiral galaxy M101 is one of the last entries in Charles Messier’s famous catalog, but definitely not one of the least. About 170,000 light-years across, this galaxy is […]