Micro-Quasar GRS1915 Puffs
2.12.1997

On the far side of our Galaxy, gas clouds explode away from a small black hole. This might seem peculiar, as black holes are supposed to attract matter. But material falling toward a black hole collides and heats up, creating an environment similar to a quasar that is far from stable.

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?

Light from a Extra Solar Planet
5.04.2005

Light emitted by a planet far beyond our Solar System has been identified for the first time. The planet, illustrated in the above drawing, had its light detected by comparing the brightness of only...

Trapezium: Teardrops in My Skies
28.02.1999

Sometimes the unexpected comes in a familiar shape. In this picture, the seemingly familiar teardrop-shaped object just right of center is actually an unusually situated disk of gas and dust. In fact, the teardrop is about the size of our own Solar System and is racing against time to condense and form planets.

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.

Lunation
2.09.2007

Our Moon's appearance changes nightly. This time-lapse sequence shows what our Moon looks like during a lunation, a complete lunar cycle. As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly visible. The Moon always keeps the same face toward the Earth.

Star Trails Over Oregon
9.09.2009

As the Earth spins on its axis, the sky seems to rotate around us. This motion, called diurnal motion, produces the beautiful concentric trails traced by stars during time exposures. Partial-circle star trails are pictured above over Grants Pass, Oregon, USA last month.

Mt. Etna Lava Plume
26.04.2017

Mt. Etna has been erupting for hundreds of thousands of years. Located in Sicily, Italy, the volcano produces lava fountains over one kilometer high. Mt. Etna is not only one of the most active...

The Crown of the Sun
23.08.2017

During a total solar eclipse, the Sun's extensive outer atmosphere, or corona, is an inspirational sight. Streamers and shimmering features visible to the eye span a brightness range of over 10,000 to 1, making them notoriously difficult to capture in a single photograph.

Harvest Moon Trail
23.09.2021

Famed in festival, story, and song the best known full moon is the Harvest Moon. For northern hemisphere dwellers that's a traditional name of the full moon nearest the September equinox. Seen from...