COMETS A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site Halley's Comet (1P/Halley) The most famous short-period comet, named for Edmond Halley who first computed its orbit and predicted its return in 1758. Records of it were subsequently traced back to 240 BC. Halley's Comet goes around the Sun once every 76 years – roughly a human lifetime. Upon its return to the inner solar system in 1986, it was met by a small flotilla of spacecraft, including ESA's Giotto, Japan’s Sakigake and Suisei, and Russia’s twin Vega probes. Giotto sent back images of Halley's potato-shaped nucleus (see photo right), measuring 16 × 8 km (10 × 5 miles). The nucleus is dark, reflecting only 4% of the sunlight falling on it, and rotates once every 3.7 days. On the sunward side, temperatures were observed to reach 77°C (350 K) which, in the zero pressure of space, is enough to turn ice into vapor. Measurements by Giotto's mass spectrometer indicated a composition for Halley of 45% water ice, 28% stony minerals, and 27% organic material. Aphelion 35.3 AU Perihelion 0.587 AU Eccentricity 0.967 Inclination 162.3° Period 76.2 years Related category    • COMETS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP