December 30, 2000
Consider this: the iron in your blood was forged in a supernova explosion billions of years ago.
A Year of Resolving Backgrounds
Birthday · December 30, 2000
A little universe, just for you
Your date.
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APOD published December 30, 2000. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
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 microkelvins.