dipper@utastro.UUCP (Debbie Byrd) (10/21/86)
The new Comet Halley -- after this. October 21 Comet Halley Comet Halley. Its legacy to us is the Orionid meteor shower -- which peaked this morning -- and the Eta Aquariid meteor shower in early May. This morning's shower was probably obliterated by bright moonlight. But today may be a good day to think again about Comet Halley itself -- that "fuzzy blob" in the sky last winter and spring -- the most famous comet in history. Some people enjoyed their view of Comet Halley -- and some were disappointed. But this comet was seen from space as well as from Earth -- and spacecraft encounters with Halley revealed the comet as no one had seen it before. The very heart -- or nucleus -- of the comet was seen by spacecraft. It measures about 10 miles long, five miles wide, and five miles high. It looks very dark -- the nucleus reflects only about four percent of the sunlight striking it. Close up, the comet's nucleus looks like a large lump with a smaller lump on one side. It appears to be mostly water-ice -- with a thin layer of some other material on its surface -- through which the comet's jets were seen to emerge. The comet's behavior earlier in this century made some scientists predict it would have jets. And so it does -- bright streams of material spewing from the comet -- some appearing to originate in craters on the surface of Halley. A new finding about the comet is that it seems to be emitting radio waves. This result -- and others obtained by spacecraft from Europe, the Soviet Union and Japan -- will have to be studied in more detail. Meanwhile, NASA wants a more extended mission of its own to another comet -- hopefully sometime in the 1990s. Script by Deborah Byrd. (c) Copyright 1985, 1986 McDonald Observatory, University of Texas at Austin