The sun is also encircled by rings, or disks, of interplanetary dust. One such ring, lying in the zone between the orbital paths of Jupiter and Mars, has long been known and is the cause of zodiacal light. Another ring was found in the inner region of the asteroids, between Mars and Jupiter, by the Infrared Astronomy Satellite ( IRAS; see also infrared astronomy) launched in 1983. Also detected in 1983, by a team of Japanese and Indonesian astronomers, was a third ring only two solar diameters away from the Sun. The dust in this ring is theorized to spiral slowly inward, because of differential absorption and reradiation of solar energy, until it is vaporized by the Sun. The resulting gases are driven back by the pressure of solar radiation.
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