September 24, 2004
The Earth has carried you around the Sun again, steady as ever, while the stars kept their patient watch.
Fornax Cluster in Motion
Birthday · September 24, 2004
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APOD published September 24, 2004. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
Reminiscent of popular images of the lovely Pleiades star cluster that lies within our own Milky Way Galaxy, this false-color x-ray view actually explores the center of a much more extended cosmic family -- the Fornax cluster of galaxies some 65 million light-years away. Spanning nearly 900,000 light-years, the Chandra Observatory composite image reveals high-energy emission from several giant galaxies near the Fornax cluster center and an immense, diffuse cloud of x-ray emitting hot gas. On the whole, the hot cluster gas seems to be trailing toward the upper left in this view. As a result, astronomers surmise that the Fornax cluster core is moving toward the lower right, encountering an intergalactic headwind as it sweeps through a larger, less dense cloud of material. In fact, along with another visible galaxy grouping at the outskirts of the cluster, the Fornax cluster core galaxies seem to be moving toward a common point, attracted by the dominating gravity of unseen structures of dark matter in the region.