The M7 Open Star Cluster in Scorpius
5.05.2002

M7 is one of the most prominent open clusters of stars on the sky. The cluster, dominated by bright blue stars, can be seen with the naked eye in a dark sky in the tail of the constellation of Scorpius.

Antares and Rho Ophiuchi
9.05.2004

Why is the sky near Antares and Rho Ophiuchi so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and so appear dark.

Leonids Over Monument Valley
19.11.2012

What's happening in the sky over Monument Valley? A meteor shower. Over the past weekend the Leonid meteor shower has been peaking. The image -- actually a composite of six exposures of about 30 seconds each -- was taken in 2001, a year when there was a much more active Leonids shower.

APOD: 2026 March 8 Б The Aurora Tree
7.03.2026

Yes, but can your tree do this? Pictured is a visual coincidence between the dark branches of a nearby tree and bright glow of a distant aurora. The beauty of the aurora -- combined with...

A Rocket Launch at Sunset
28.09.2005

What kind of cloud is that? Last week, a sunset rocket launch lit up the sky and was photographed by sky enthusiasts as far as hundreds of miles away. The lingering result was a photogenic rocket plume.

Martian Analemma
29.12.2006

On planet Earth, an analemma is the figure-8 loop you get when you mark the position of the Sun at the same time each day throughout the year. But similarly marking the position...

Gamma Cas and Friends
23.12.2009

Gamma Cassiopeiae shines high in northern autumn evening skies. The brightest spiky star in this rich and colorful Milky Way starfield, bluish Gamma Cas marks the central peak in the W-shaped constellation Cassiopeia.

Perseid over Albrechtsberg Castle
9.08.2013

Medieval Albrechtsberg castle is nestled in trees near the northern bank of the river Pielach and the town of Melk, Austria. In clearing night skies on August 12, 2012 it stood under constellations of the northern summer, including Aquarius, Aquila, and faint, compact Delphinus (above and right of center) in this west-looking skyview.

Dark Dust and Colorful Clouds near Antares
26.08.2019

Why is the sky near Antares and Rho Ophiuchi so dusty yet colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae.

Globular Star Cluster 47 Tuc
23.10.2020

Globular star cluster 47 Tucanae is a jewel of the southern sky. Also known as NGC 104, it roams the halo of our Milky Way Galaxy along with some 200 other globular star clusters.