Equinox on a Spinning Earth
21.09.2021

When does the line between night and day become vertical? Today. Today is an equinox on planet Earth, a time of year when day and night are most nearly equal. At an equinox, the Earth's terminator -- the dividing line between day and night -- becomes vertical and connects the north and south poles.

APOD: 2024 January 29 Б The Pleiades: Seven Dusty Sisters
28.01.2024

The well-known Pleiades star cluster is slowly destroying part of a passing cloud of gas and dust. The Pleiades is the brightest open cluster of stars on Earth's sky and can be seen from almost any northerly location with the unaided eye.

APOD: 2026 January 5 Б The Red Rectangle Nebula from Hubble
4.01.2026

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 colors. The unusual...

APOD: 2026 March 11 Б CG 4: The Globule and the Galaxy
10.03.2026

Is this a cosmic monster ready to devour an unsuspecting galaxy? Thankfully, that is not the case. The red БmonsterБ shown in the featured image is Cometary Globule CG 4, 1,300 light-years away in the Constellation Puppis.

APOD: 2026 August 8 Б A Messier Moment for Tempel 2
7.08.2026

Which of these is not a comet? You guessed it - the one on the right is a globular star cluster. The diffuse greenish coma of periodic comet 10P/Tempel 2 is at left in the frame.

Io s Surface: Under Construction
19.10.2002

Like the downtown area of your favorite city, the roads you drive to work on, and any self-respecting web site ... Io's surface is constantly under construction. This moon of Jupiter holds the distinction of being the Solar System's most volcanically active body -- its bizarre looking surface continuously formed and reformed by lava flows.

Orion Rising
24.12.2002

Orion always comes up sideways ... and was caught in the act earlier this month by astronomer Jimmy Westlake, stargazing eastward over the Rocky Mountains north of Leadville, Colorado, USA. To make this gorgeous image, Westlake placed his camera on a tripod for two exposures.

Supernova Remnant E0102 72 from Radio to X-Ray
14.04.2000

Not all stars form a big Q after they explode. The shape of supernova remnant E0102-72, however, is giving astronomers a clue about how tremendous explosions disperse elements and interact with surrounded gas. The above image is a composite of three different photographs in three different types of light.

Reflections on the 1970s
19.12.2007

The 1970s are sometimes ignored by astronomers. In particular, this beautiful grouping of reflection nebulae in Orion - NGC 1977, NGC 1975, and NGC 1973 - are usually overlooked in favor of the substantial glow from the nearby stellar nursery better known as the Orion Nebula.

La Silla Star Trails North and South
2.02.2012

Fix your camera to a tripod and you can record graceful trails traced by the stars as planet Earth rotates on its axis. If the tripod is set up at ESO's La Silla Observatory, high in the Atacama desert of Chile, your star trails would look something like this.