Trio Leo
9.03.2006

This popular group is famous as the Leo Triplet - a gathering of three magnificent galaxies in one field of view. Crowd pleasers when imaged with even modest telescopes, these galaxies can be introduced individually as NGC 3628 (top), M66 (bottom left), and M65 (bottom right). All three are large spiral galaxies.

100 Hours of Astronomy Begins
2.04.2009

Today, 100 Hours of Astronomy begins, a cornerstone project of the International Year of Astronomy 2009 celebrating the 400th anniversary of Gallileo's original telescopic exploration of the sky. Running from April 2 through...

A Green Flash from the Sun
4.01.2011

Many think it is just a myth. Others think it is true but its cause isn't known. Adventurers pride themselves on having seen it. It's a green flash from the Sun. The truth is the green flash does exist and its cause is well understood.

APOD: 2024 October 6 Б The Magnificent Tail of Comet McNaught
6.10.2024

Comet McNaught, the Great Comet of 2007, grew a spectacularly long and filamentary tail. The magnificent tail spread across the sky and was visible for several days to Southern Hemisphere observers just after sunset. The amazing ion tail showed its greatest extent on long-duration, wide-angle camera exposures.

APOD: 2025 January 8 Б Supernova Remnants Big and Small
8.01.2025

What happens after a star explodes? A huge fireball of hot gas shoots out in all directions. When this gas slams into the existing interstellar medium, it heats up so much it glows. Two different supernova remnants (SNRs) are visible in the featured image, taken at the Oukaцmeden Observatory in Morocco.

Comet Kudo-Fujikawa: Days in the Sun
30.01.2003

Cruising through the inner Solar System, new Comet Kudo-Fujikawa reached perihelion, its closest approach to the Sun, yesterday, January 29. Passing within 28.4 million kilometers of the Sun, this comet came much closer than innermost planet Mercury basking only 57.9 million kilometers from our parent star.

The Swarm
29.07.2006

What do you call a group of black holes ... a flock, a brace, a swarm? Monitoring a region around the center of our Galaxy, astronomers have indeed found evidence for a surprisingly large number...

APOD: 2026 March 25 Б The Guardians of Rapa Nui beneath the Milky Way
25.03.2026

In the words of today's astrophotographer, Rositsa Dimitrova, "What have these silent sentinels watched pass across the sky?" The volcanic mo'ai (meaning statue) of Ahu Tongariki stand guard over Rapa Nui (Isla...

Moon Mare and Montes
28.12.2000

This arresting image of the third quarter moon in the excellent skies above the Pine Crest Farm Observatory, Dell Prairie, Wisconsin, was recorded with a 24 inch telescope and digital camera on October 19.

TT Cygni: Carbon Star
18.12.1998

TT Cygni is a cool red giant star with a wind. This false-color picture of TT Cyg was made using a coordinated array of millimeter wavelength radio telescopes and shows radio emission from carbon monoxide (CO) molecules in the surrounding gas.