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Out-of-this-world view of the Milky Way.



Out-of-this-world view of the Milky Way Milky Way, the galaxy of which the sun and solar system are a part, seen as a broad band of light arching across the night sky from horizon to horizon; if not blocked by the horizon, it would be seen as a circle around the entire sky.  

Measurements of infrared radiation detected by an instrument aboard the Cosmic Background Explorer Cosmic Background Explorer: see infrared astronomy.
Cosmic Background Explorer (COBE)

U.S. satellite that from 1989 to 1993 mapped the cosmic background radiation field. In 1964, microwave radiation was discovered that permeated the cosmos uniformly.
 (COBE COBE: see infrared astronomy. ) spacecraft have allowed researchers to construct a unique portrait of the inner portion of the Milky Way.

"We see for the first time a very clear picture of our galaxy, with its nuclear bulge of stars," says Micahel G. Hauser of the NASA NASA: see National Aeronautics and Space Administration.
NASA
 in full National Aeronautics and Space Administration

Independent U.S.
 Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately 6.5 miles northeast of Washington, D.C.  in Greenbelt, Md. "This is what our galaxy looks like in starlight."

Astronomers have long pictured the Milky Way as a spiral galaxy -- a large, flattened disk of stars orbiting a common center. But direct, visual evidence for that view has been sparse. Although the sun traces an orbit near the fringes of the Milky Way, Earth-based observers have difficulty seeing through the dust that threads the galaxy's disk and surrounds its core. At visible wavelengths, they see only the relatively dust-free parts.

The new portrait of the Milky Way combines images obtained at three near-infrared wavelengths: 1.2 microns (represented in blue), 2.2 microns (green) and 3.4 microns (red). These wavelengths, slightly longer than those of visible light, correspond to radiation emitted mainly by stars rather than by dust particles, which absorb visible light and then reradiate re·ra·di·ate  
tr.v. re·ra·di·at·ed, re·ra·di·at·ing, re·ra·di·ates
To emit (absorbed radiation) anew: "Different organic materials in the soil reradiate the sun's heat at different rates" 
 that energy as infrared radiation. The image appears redder in directions where dust absorption is stronger. Images constructed previously from data obtained by the Infrared Astronomical Statellite revealed the sky's appearance at longer infrared wavelengths, where dust emissions play a much greater role.

The COBE-derived picture shows only that part of the galaxy closer to the galactic center than the sun, which orbits about 20,000 light-years out from the center. Discrete points that appear away from the Milky Way's central disk correspond to individual stars in the sun's immediate neighborhood.

"It's a spectacular image," says David T. Wilkinson of Princeton (N.J.) University. "It's almost as though you were in Andromeda [a nearby galaxy], taking a picture of our galaxy."

The new view is "one of the fringe benefits fringe benefits,
n.pl the benefits, other than wages or salary, provided by an employer for employees (e.g., health insurance, vacation time, disability income).
" of COBE program designed to provide a detailed infrared map of the sky, Hauser says. By looking for Looking for

In the context of general equities, this describing a buy interest in which a dealer is asked to offer stock, often involving a capital commitment. Antithesis of in touch with.
 regions in the sky with the smallest possible infrared signal, investigators hope to find the fossil residue of light given off by the first luminous objects created after matter started to collapse into lumps early in the Universe's history. That search requires separating the faint, primordial infrared signal from the intense infrared sources now active within the galaxy and solar system (SN: 1/20/90, p.36).
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Author:Peterson, I.
Publication:Science News
Date:Apr 28, 1990
Words:422
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