The Lyman Alpha Forest
25.01.2003

We live in a forest. Strewn throughout the universe are "trees" of hydrogen gas that absorb light from distant objects. These gas clouds leave numerous absorption lines in a distant quasar's spectra, together called the Lyman-alpha forest.

Perseid Meteors and the Milky Way
15.08.2005

Where will the next Perseid meteor appear? Sky enthusiasts who trekked outside for the Perseid meteor shower that peaked over the past few days typically had this question on their mind. The above movie, where the time-line has been digitally altered, captures part of that very mystery.

Warped Spiral Galaxy ESO510 13
12.05.1999

How did spiral galaxy ESO510-13 get bent out-of-shape? The disks of many spirals are thin and flat, but not solid. Spiral disks are loose conglomerations of billions of stars and diffuse gas all gravitationally orbiting a galaxy center.

A Twisted Solar Eruptive Prominence
3.04.2000

A huge eruptive prominence is seen moving out from our Sun in this condensed half-hour time-lapse sequence. Ten Earths could easily fit in the "claw" of this seemingly solar monster. This large prominence, though, is significant not only for its size, but its shape.

Eta Carinae in X Rays
11.10.1999

Eta Carinae is the one of the most luminous star systems in our Galaxy, radiating millions of times more power than our Sun. Eta Carinae is also one of the strangest star systems known, brightening and fading greatly since the early 1800s.

From the Northern to the Southern Cross
26.01.2019

There is a road that connects the Northern to the Southern Cross but you have to be at the right place and time to see it. The road, as pictured here, is actually...

The Gamma Ray Sky
20.03.1998

What if you could "see" gamma rays? If you could, the sky would seem to be filled with a shimmering high-energy glow from the most exotic and mysterious objects in the Universe.

The North Pole Of Mars
24.09.1998

The North Pole of Mars is capped by layers likely consisting of ice and dust deposited over millions of years. Imaged on September 12 - early Spring for Northern Mars - by the Mars Global Surveyor's camera, this synthesized wide-angle color view shows the rippled, eroded polar terrain covered with pinkish seasonal carbon dioxide frost.

APOD: 2025 November 26 Б Globular Cluster M15 Deep Field
25.11.2025

Stars, like bees, swarm around the center of bright globular cluster M15. The central ball of over 100,000 stars is a relic from the early years of our Galaxy, and continues to orbit the Milky Way's center.

The Lyman Alpha Forest
23.02.1998

We live in a forest. Strewn throughout the universe are "trees" of hydrogen gas that absorb light from distant objects. These gas clouds leave numerous absorption lines in a distant quasar's spectra, together called the Lyman-alpha forest.