NASA’s technology demonstration spacecraft DS1 imaged the nucleus of Comet Borrelly in 2001. In 1986, five spacecraft from the USSR, Japan, and the European Community visited Comet Halley ESA’s Giotto obtained close-up photos of Halley’s nucleus (above and right). NASA’s ICE passed through the tail of Comet Giacobini-Zinner in 1985 Comet Grigg Skjellerup was visited by Giotto in 1989. Only four comets have been visited by spacecraft. Halley’s orbit is retrograde and inclined 18 degrees to the ecliptic. Its next perihelion passage will be in early 2062.
Its most famous appearance was in 1066 when it was seen at the Battle of Hastings, an event commemorated in the Bayeux Tapestry.Ĭomet Halley was visible in 1910 and again in 1986. The closest perihelion passage to the time of Jesus are 11 BC and 66 AD neither event took place in Jesus’ lifetime. Between the years 239 BC and 1986 AD the orbital period has varied from 76.0 years (in 1986) to 79.3 years (in 4). Nongravitational effects (such as the reaction from gasses boiled off during its passage near the Sun) also play an important, but smaller, role in altering the orbit. The gravitational pull of the major planets alters the orbital period from revolution to revolution. The average period of Halley’s orbit is 76 years but you cannot calculate the dates of its reappearances by simply subtracting multiples of 76 years from 1986. The comet did indeed return as predicted and was later named in his honor. In 1705 Edmond Halley predicted, using Newton’s newly formulated laws of motion, that the comet seen in 1531, 1607, and 1682 would return in 1758 (which was, alas, after his death).