COBE


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COBE:

see infrared astronomyinfrared astronomy,
study of celestial objects by means of the infrared radiation they emit, in the wavelength range from about 1 micrometer to about 1 millimeter. All objects, from trees and buildings on the earth to distant galaxies, emit infrared (IR) radiation.
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COBE

(koh -bee) Abbrev. for Cosmic Background Explorer. A NASA orbiting satellite launched Nov. 18 1989 and dedicated to the study of the cosmic microwave background radiation, and hence to cosmology. The mission ran for just over four years, being terminated by NASA on Dec. 23 1993.

COBE's scientific payload consisted of three instruments shielded from the adverse thermal and radiation effects of the Sun and Earth. Two cryogenically cooled instruments observed the sky at infrared wavelengths. DIRBE, the diffuse infrared background experiment, mapped the sky at 10 wavelengths over 1–300 μm in search of the cumulative uniform glow from earliest luminous objects. FIRAS, the far-infrared absolute spectrophotometer, measured the average temperature of the background with unprecedented precision: it showed the spectrum of the microwave background to be a perfect black body curve characteristic of a temperature of 2.735 ± 0.06 K. FIRAS was turned off after 10 months of flight when the helium coolant ran out.

The third detector, the DMR (differential microwave radiometer), consisted of six differential radiometers observing the sky at three radio wavelengths – 3.3, 5.7, and 9.5 mm. They made whole-sky surveys and were designed to detect any fluctuations in the brightness of the microwave background.

The microwave background is not completely uniform, showing a slight dipole anisotropy with an enhancement of one part in a thousand in the direction of the Galaxy's motion and an equal and opposite deficit in the opposite part of the sky. This results from the real motion of the Galaxy relative to the fixed background. It was announced in April 1992 that careful statistical analysis of the COBE measurements also revealed even weaker temperature fluctuations of one part in one hundred thousand on scales of ten degrees and larger. These are the imprints of quantum fluctuations in the early Universe. Further study of such fluctuations by such missions as the Wilkinson Microwave Anisotropy Probe have served to constrain cosmological models that determine how the early inhomogeneities collapsed to form the large-scale structure we see in today's Universe.

References in periodicals archive ?
3 The anisotropy of the Earth microwave background in the COBE orbit and at the L2 point
In addition to the "CMB" monopole, the COBE satellite reports a dipole signature associated with motion [7], confirming Relikt-1 findings [13].
In the end, the press credited the most celebrated COBE discovery to Smoot in a manner that some felt exceeded the usual media personalization of a scientific paper with its lead author.
The anisotropy in the Background measured by the differential instruments is actually the same: DMR at COBE registered the anisotropy 3.
Subsequent transfers may generate tax consequences, including deferred gain, but the requirements for COBE and the underlying reorganization will be satisfied.
It was this very precise spectrum, not the temperature irregularities COBE observed later, that truly lent the greatest support to the Big Bang.
This agrees with published, first-year COBE maps, the team reports in the Jan.
This picture is in agreement with the interpretations of the COBE [13] measurements giving the Earth's "absolute" velocity in relation to the uniform cosmic microwave background radiation (CMBR).
COBE generally requires the Acquiror to either continue a significant historic Target business or use a significant portion of Target's historic business assets in a business.
Smoot first offers the modern, founding cosmological theories; then he gives a firsthand, behind-the-scenes description of his early experiments that gradually led to COBE.
The microwave background seems to represent the cooled relic radiation left over from a hot expansion, and its predicted smoothness has now been verified to high precision by COBE.
Although P's business has not been continued, Q uses a significant portion of P's assets, meeting the COBE rules.