Science

Landsat 6, DIRBE/COBE, LEP/CERN, Oxford University


The COBE satellite was developed by NASA's Goddard Space Flight Center to measure the diffuse infrared and microwave radiation from the early universe to the limits set by our astrophysical environment. It was launched November 18, 1989 and carried three instruments, a Diffuse Infrared Background Experiment (DIRBE) to search for the cosmic infrared background radiation, a Differential Microwave Radiometer (DMR) to map the cosmic radiation sensitively, and a Far Infrared Absolute Spectrophotometer (FIRAS) to compare the spectrum of the cosmic microwave background radiation with a precise blackbody.

Thermal emission from star-heated dust in the Milky Way and interplanetary dust heated by the Sun dominates the images at these wavelengths. The S-shaped feature is the ecliptic plane, in which, like the planets, the interplanetary dust is concentrated. The oval-shaped brightness discontinuity is an artefact of the way the maps were prepared, not a feature in the infrared sky. Specifically, the discontinuity corresponds to a path difference through the interplanetary dust cloud as adjacent positions in the sky were observed from DIRBE's vantage point in Earth orbit with the Earth on opposite sides of the Sun.