A Year of Resolving Backgrounds

No matter which direction you look, no matter what type of light you see, the sky glows - but why? The sources of many of these background radiations have remained long-standing puzzles, but this millennial year brought some partial resolutions. In X-ray light the recently launched spacecraft Chandra and XMM resolved much of the seemingly uniform X-ray background into many discrete sources, many of which appear to be black holes at the centers of galaxies accreting matter. In microwave light , the BOOMERANG and MAXIMA-1 missions resolved with new clarity the seemingly uniform microwave background . The size and distribution of these spots indicates a geometrically flat universe , which, when combined recent supernovae results , indicate a universe with an accelerating expansion rate filled with dark matter and dark energy . Pictured above , a map spanning ten degrees of the microwave sky resolves the microwave background into hot and cold spots, as indicated in micro kelvins .