Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2004 September 24
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Fornax Cluster in Motion
Credit: C. A. Scharf, D. R. Zurek, M. Bureau (Columbia Univ.), CXC, NASA

Explanation: Reminiscent of popular images of the lovely Pleiades star cluster that lies within our own Milky Way Galaxy, this false-colour x-ray view actually explores the centre 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 centre 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.

Tomorrow's picture: light-weekend


< | Archive | Index | Search | Calendar | Glossary | Education | About APOD | >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.