Telescopes from the Ground Up

A space telescope helps astronomers picture the early universe

The Cosmic Background Explorer, COBE, was launched in 1989 to study the faint infrared and microwave radiation from the early universe called cosmic background radiation. Scientists believe this radiation is left over from the Big Bang — the chain reaction that formed the universe.

COBE was sent into an orbit high above Earth’s atmosphere, where it could view this radiation. It had three instruments on board: one to observe infrared radiation, one to map microwave radiation, and one to measure the cosmic background radiation’s spectrum.

COBE used solar panels to collect light from the Sun for energy, and a funnel-shaped sunshade to keep the light from shining on and heating the cold parts of the satellite. In addition, liquid hydrogen helped keep the telescope cool. COBE had to stay extremely cold because it was studying infrared light, or heat. Unless the satellite and its detector could be kept cool, it would give off infrared signals of its own that would interfere with the infrared signals it was trying to detect.

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Space Telescopes
Diagram of the orbit of the Cosmic Background Explorer around Earth.
Artist illustration of the Csomic Background Explorer in orbit.Enlarge picture
The Cosmic Background Explorer (COBE)
Year launched: 1989
Telescope type: Detector
Light collector: Microwave receivers
Light observed: Microwave, infrared
Discovery Highlights:
  • Found that the very young universe was not uniform — some places had slightly more matter than others. This clumpiness provided gravitational "seeds" from which galaxies, stars, and planets grew.