Halley’s Comet
  • This best-known comet, publicly notorious because it reappears predictably and is bright enough to be seen with the naked eye. These factors also make it fascinating to astronomers: its brightness and the fact that it spends almost all of its 76 year orbit in deep space mean that Halley’s Comet is an almost unaltered chunk of material from the earliest days of the solar system, which presents itself for observation at predictable intervals. The comet’s 1986 appearance was greeted by a shoal of spacecraft from Europe, Japan and the USSR (especially ESA’s Giotto, which flew closest to the Comet’s nucleus), and was viewed by thousands of terrestrial observers.

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