In astronomer-speak, metals refer to elements heavier than helium. The first stars that lit up the universe were very metal-poor, since hydrogen and helium were just about the only materials around ...

This evening, the small constellation Lacerta sits just below cross-shaped Cygnus in the eastern sky after dark. The zig-zagging outline of the Lizard lies roughly 20° east (to the lower left early in ...

Mars and the crescent Moon hang together in the early-morning sky, straddling the border of Gemini and Taurus.

A total eclipse of the Sun coincides with the peak of the annual Perseid shower, plus Venus reaches dichotomy in the sky this ...

The Little Gem is a lovely blue-green planetary nebula that shines brightly in the southern sky near Sagittarius' Teapot ...

The Moon passes in front of the stars of the Pleiades, visible in the eastern U.S., while distant ice giant Uranus hangs ...

Mercury sits a few degrees due south of Pollux in Gemini early this morning, while Mars lies higher up along the ecliptic.

Solar and lunar eclipses both occur this month, as Mars and Jupiter meet in the early morning and the Perseid meteor shower peaks.

Saturn’s two-toned moon Iapetus passes through superior conjunction, sitting just south of the ringed world this morning.

Rising shortly after sunset, July’s Full Moon, called the Buck Moon, dominates the sky tonight with its bright light.

Mercury reaches its greatest western elongation, Iapetus passes close to Saturn, and the Moon occults the Pleiades in the sky ...

The waning Moon steps up to form a triangle in the early-morning sky with two distant planets: Saturn and Neptune.