Website review: APOD: 2007 October 8 - Galaxy NGC ...
starspirit discovered this in Astronomy
•1 reviews since Oct 7, 2007
astronomy
•antwrp.gsfc.nasa.gov/apod/ap071008.html
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laodan rated 9 months ago- Unexpectedly high complexity in Nasa's Astronomy Picture of the Day
Credit & Copyright: Mischa Schirmer Explanation: What's happening to galaxy NGC 474? The multiple layers of emission appear strangely complex and unexpected given the relatively featureless appearance of the elliptical galaxy in less deep images. The cause of the shells is currently unknown, but possibly tidal tails related to debris left over from absorbing numerous small galaxies in the past billion years. Alternatively the shells may be like ripples in a pond, where the ongoing collision with the spiral galaxy to the right of NGC 474 is causing density waves to ripple though the galactic giant. Regardless of the actual cause, the above image dramatically highlights the increasing consensus that the outer halos of most large galaxies are not really smooth but have complexities induced by frequent interactions with -- and accretions of -- smaller nearby galaxies. NGC 474 spans about 250,000 light years and lies about 100 million light years distant toward the constellation of the Fish Pisces. Galaxy NGC 474: Cosmic Blender
Two Million Galaxies Credit & Copyright: S. Maddox (Nottingham U.) et al. APM Survey, Astrophys. Dept. Oxford U. Explanation: Our universe is filled with galaxies. Galaxies -- huge conglomerations of stars, gas, dust -- and mysterious dark matter are the basic building blocks of the large-scale universe. Although distant galaxies move away from each other as the universe expands, gravity attracts neighboring galaxies to each other, forming galaxy groups, clusters of galaxies, and even larger expansive filaments. Some of these structures are visible on one of the most comprehensive maps of the sky ever made in galaxies: the APM galaxy survey map completed in the early 1990s. Over 2 million galaxies are depicted above in a region 100 degrees across centered toward our Milky Way Galaxy's south pole. Bright regions indicate more galaxies, while bluer colors denote larger average galaxies. Dark ellipses have been cut away where bright local stars dominate the sky. Those 2 images give us a good visualization of the utter complexity of our universe, or better, of our island universe in Villenkin's terminology.
- Unexpectedly high complexity in Nasa's Astronomy Picture of the Day
