For some, these subtle bands of light and shadow stretched across the sky as the Sun set on July 11. Known as anticrepuscular rays, the bands are formed as a […]

Unlike most entries in Charles Messier’s famous catalog of deep sky objects, M24 is not a bright galaxy, star cluster, or nebula. It’s a gap in nearby, obscuring interstellar dust […]

When Vulcan, the Roman god of fire, swings his blacksmith’s hammer, the sky is lit on fire. A recent eruption of Chile’s Villarrica volcano shows the delicate interplay between this […]

Globular star cluster Omega Centauri packs about 10 million stars much older than the Sun into a volume some 150 light-years in diameter. Also known as NGC 5139, at a […]

These three bright nebulae are often featured on telescopic tours of the constellation Sagittarius and the crowded starfields of the central Milky Way. In fact, 18th century cosmic tourist Charles […]

These clouds are doubly unusual. First, they are rare noctilucent clouds, meaning that they are visible at night — but only just before sunrise or just after sunset. Second, the […]

Do other stars have planets like our Sun? Surely they do, and evidence includes slight star wobbles created by the gravity of orbiting exoplanets and slight star dimmings caused by […]

Why are these clouds multi-colored? A relatively rare phenomenon in clouds known as iridescence can bring up unusual colors vividly — or even a whole spectrum of colors simultaneously. These […]

Found among the rich starfields of the Milky Way, star cluster NGC 7789 lies about 8,000 light-years away toward the constellation Cassiopeia. A late 18th century deep sky discovery of […]

A glow from the summit of Mount Etna, famous active stratovolcano of planet Earth, stands out along the horizon in this mountain and night skyscape. Bands of diffuse light from […]