Sparkling Star May Indicate Galactic Composition
24.06.1998

If a star in this photograph twinkled slightly, would anyone notice? Would anyone care? Astronomers with the MACHO Collaboration noticed one such twinkle just last week, and many members of the astronomical community now care.

Shadow of a Martian Robot
4.02.2007

What if you saw your shadow on Mars and it wasn't human? Then you might be the Opportunity rover currently exploring Mars. Opportunity and sister robot Spirit have been probing the red planet since early 2004, finding evidence of ancient water, and sending breathtaking images across the inner Solar System.

M31: The Andromeda Galaxy
10.05.2009

Andromeda is the nearest major galaxy to our own Milky Way Galaxy. Our Galaxy is thought to look much like Andromeda. Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of billions of stars that compose it.

The Gum Nebula
22.08.2009

Named for Australian astronomer Colin Stanley Gum (1924-1960), The Gum Nebula is so large and close it is actually hard to see. In fact, we are only about 450 light-years from the front edge and 1,500 light-years from the back edge of this cosmic cloud of glowing hydrogen gas.

Prometheus and the F Ring
8.01.2016

In Greek myth Prometheus was a Titan, known for bringing fire from Mount Olympus. But in modern times the name is given to is a small moon of Saturn, orbiting just inside Saturn's F ring.

A Starry Night of Iceland
5.01.2020

On some nights, the sky is the best show in town. On this night, the sky was not only the best show in town, but a composite image of the sky won an international competition for landscape astrophotography. The featured winning image was taken in 2011 over JЖkulsАrlСn, the largest glacial lake in Iceland.

APOD: 2023 February 21 Б Comet ZTF over Yosemite Falls
21.02.2023

They are both falling. The water in Yosemite Falls, California, USA, is falling toward the Earth. Comet ZTF is falling toward the Sun. This double cosmic cascade was captured late last month as fading Comet C/2022 E3 (ZTF) had just passed its closest to planet Earth. The orange star just over the falls is Kochab.

APOD: 2024 April 22 Б Moon and Smoke Rings from Mt Etna
22.04.2024

Yes, but can your volcano do this? To the surprise of some, Mt. Etna emits, on occasion, smoke rings. Technically known as vortex rings, the walls of the volcano slightly slow the outside of emitted smoke puffs, causing the inside gas to move faster.

Meteors Between Stars and Clouds
11.12.2002

Streaking high above diffuse clouds -- but well in front of distant stars -- are sand-sized bits of an ancient comet: meteors. These bits flaked off Comet Tempel-Tuttle during its pass through the inner Solar System about 150 years ago. Far in the background are stars toward the constellation of Ursa Major.

A Path To Orion
16.12.2006

Last Saturday, the Space Shuttle Discovery lit up the night as it climbed into orbit above planet Earth. From Oak Hill, Florida, USA - about 30 miles north of the Kennedy Space Center - design engineer...