A Path North
7.04.2020

What happens if you keep going north? The direction north on the Earth, the place on your horizon below the northern spin pole of the Earth -- around which other stars appear to slowly swirl, will remain the same.

Star Colors in Orion
11.02.2011

What determines a star's color? Its temperature. Red stars are cool, with surface temperatures of around 3,000 kelvins (K), while blue stars are hotter and can have temperatures over 30,000 K. Our own lovely "yellow" Sun's temperature is a comforting 6,000 K.

Fox Fur, Unicorn, and Christmas Tree
7.02.2019

Clouds of glowing hydrogen gas fill this colorful skyscape in the faint but fanciful constellation Monoceros, the Unicorn. A star forming region cataloged as NGC 2264, the complex jumble of cosmic gas and dust...

The Medusa Nebula
12.06.2015

Braided, serpentine filaments of glowing gas suggest this nebula's popular name, The Medusa Nebula. Also known as Abell 21, this Medusa is an old planetary nebula some 1,500 light-years away along the southern border of the constellation Gemini. Like its mythological namesake, the nebula is associated with a dramatic transformation.

The Radio Sky: Tuned to 408MHz
5.02.2005

Tune your radio telescope to 408MHz (408 million cycles per second) and check out the Radio Sky! In the 1970s large dish antennas at three radio observatories, Jodrell Bank, MPIfR, and Parkes Observatory, were used to do just that - the data were combined to map the entire sky.

Unusual Dusty Galaxy NGC 7049
8.04.2009

How was this unusual looking galaxy created? No one is sure, especially since spiral galaxy NGC 7049 looks so strange. NGC 7049's strikingly appearance is primarily due to an unusually prominent dust ring seen mostly in silhouette. The opaque ring is much darker than the din of millions of bright stars glowing behind it.

NGC 1365: Barred Spiral Galaxy
8.10.1999

NGC 1365 is a giant barred spiral galaxy about 200,000 light-years in diameter and 60 million light-years distant in the southern constellation Fornax. These three recently released images offer views of this majestic island universe in visible and infrared light.

Proxima Centauri: The Closest Star
15.07.2002

What is the closest star to our Sun? It is Proxima Centauri, the nearest member of the Alpha Centauri triple star system. Light takes only 4.22 years to reach us from Proxima Centauri. This...

APOD: 2024 January 9 Б Thors Helmet
9.01.2024

Thor not only has his own day (Thursday), but a helmet in the heavens. Popularly called Thor's Helmet, NGC 2359 is a hat-shaped cosmic cloud with wing-like appendages. Heroically sized even for a Norse god, Thor's Helmet is about 30 light-years across.

Perseid Below
17.08.2011

Denizens of planet Earth watched this year's Perseid meteor shower by looking up into the moonlit night sky. But this remarkable view captured by astronaut Ron Garan looks down on a Perseid meteor.