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Astronomy Picture Of the Day (APOD)
Star Size Comparisons
22.02.2011
How big is our Sun compared to other stars? In a dramatic and popular video featured on YouTube, the relative sizes of planets and stars are shown from smallest to largest. The above video starts with Earth's Moon and progresses through increasingly larger planets in our Solar System.
Milky Way Over Switzerland
21.02.2011
What's visible in the night sky during this time of year? To help illustrate the answer, a beautiful land, cloud, and skyscape was captured earlier this month over NeuchБtel, Switzerland. Visible in the foreground were the snow covered cliffs of the amphitheater shaped Creux du Van, as well as distant trees, and town-lit clouds.
Mammatus Clouds Over Olympic Valley
20.02.2011
What's happened to these clouds? Normal cloud bottoms are flat because moist warm air that rises and cools will condense into water droplets at a very specific temperature, which usually corresponds to a very specific height. After water droplets form that air becomes an opaque cloud.
Spiral Galaxy NGC 2841 Close Up
19.02.2011
A mere 46 million light-years distant, spiral galaxy NGC 2841 can be found in the northern constellation of Ursa Major. This sharp view of the gorgeous island universe shows off a striking yellow nucleus and galactic disk.
Planetary Nebula Project
18.02.2011
Cast off by dying sunlike stars, planetary nebulae are a brief but glorious final phase of stellar evolution. The gaseous shrouds are ionized by an extremely hot central source, the shrinking core of a star running out of fuel for nuclear fusion.
X Class Flare
17.02.2011
On Valentine's Day (ET) the Sun unleased one of its most powerful explosions, an X-class flare. The blast was the largest so far in the new solar cycle. Erupting from active region AR1158...
Comet Tempel 1 from Stardust NeXT Spacecraft
16.02.2011
No comet has ever been visited twice before. Therefore, the unprecedented pass of the Stardust-NeXT spacecraft near Comet Tempel 1 earlier this week gave humanity a unique opportunity to see how the nucleus of a comet changes over time.
The North America Nebula in Infrared
15.02.2011
The North America Nebula can do what most North Americans cannot -- form stars. Precisely where in the nebula these stars are forming has been mostly obscured by some of the nebula's thick dust that is opaque to visible light.
The Rosette Nebula
14.02.2011
Would the Rosette Nebula by any other name look as sweet? The bland New General Catalog designation of NGC 2237 doesn't appear to diminish the appearance of this flowery emission nebula. Inside the nebula lies an open cluster of bright young stars designated NGC 2244.
Ice Fishing for Cosmic Neutrinos
13.02.2011
Scientists are melting holes in the bottom of the world. In fact, almost 100 holes melted near the South Pole are now being used as astronomical observatories. Astronomers with the IceCube Neutrino Observatory lowered into each vertical lake a long string knotted with basketball-sized light detectors. The water in each hole soon refreezes.
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