Identify this Phenomenon
13.09.2004

What caused this ring of colors? At the time of this writing, MIT Physics Professor Walter Lewin had yet to find someone who can give the correct explanation. Not students. Not colleagues. Not APOD editors. He wonders how the astute readers of APOD will do. Can you match wits with Professor Lewin?

The Swirling Storms of Saturn
10.10.2005

Storms larger than hurricanes continually dot the upper atmosphere of the planet Saturn. A view of many storms occurring simultaneously was captured in July by the robot Cassini spacecraft now orbiting Saturn. An image of unusually high detail was made possible at that time when Cassini isolated a very specific color of polarized infrared light.

One Armed Spiral Galaxy NGC 4725
6.06.2009

While most spiral galaxies, including our own Milky Way, have two or more spiral arms, NGC 4725 seems to have only one. In this sharp color image, the solo spira mirabilis is tightly wound, traced by bluish, newborn star clusters.

Aurora at Midnight
5.05.1998

What's happening behind those trees? Aurora. This picture was taken at midnight near Fairbanks, Alaska, and captures familiar trees, common clouds, and a glowing sky markedly different than a sunset. Particularly strange is the green auroral ring caused by ionized oxygen high in the Earth's atmosphere.

NGC 3132: The Eight Burst Nebula
10.11.1998

It's the dim star, not the bright one, near the center of NGC 3132 that created this odd but beautiful planetary nebula. Nicknamed the Eight-Burst Nebula and the Southern Ring Nebula, the glowing gas originated in the outer layers of a star like our Sun.

M83: The Southern Pinwheel Galaxy from VLT
11.05.2003

M83 is one of the closest and brightest spiral galaxies on the sky. Visible with binoculars in the constellation of Hydra, majestic spiral arms have prompted its nickname as the Southern Pinwheel. Although discovered...

A Complete Aurora
2.04.1997

Aurora frequently make complete rings around a pole of the Earth. This particular "crown", visible in orange near the top of this image, was taken by the orbiting Polar spacecraft about one year ago and released by NASA last month.

Eclipse Madrid
7.10.2005

A walk in the park seemed like a perfect idea to many enjoying a sunny October morning in Madrid, Spain. Of course, on October 3rd an added attraction was the Moon - seen in dramatic silhouette during an annular solar eclipse.

Star Party on Planet Earth
4.04.2009

As twilight sweeps around planet Earth tonight (April 4), many amateur astronomers will set up their telescopes for a 24-hour global star party. The planetwide star party is part of 100 Hours of Astronomy (100HA), a project of the International Year of Astronomy 2009.

Brisbane Sunset Moonset
1.05.2014

In skies over Brisbane at the southeastern corner of Queensland, Australia, Planet Earth, the Sun and New Moon set together on April 29. There the celestial line-up, the first solar eclipse of 2014, was seen as a partial solar eclipse.