mirrored file at http://SaturnianCosmology.Org/ For complete access to all the files of this collection see http://SaturnianCosmology.org/search.php ========================================================== _Halley's Comet_ _[13]Spacecraft that have visited Halley's Comet_ [14][LINK] _Halley's_ [HAL-lee] _Comet_ has been know since at least 240 BC and possibly since 1059 BC. Its most famous appearance was in 1066 AD when it was seen right before the Battle of Hastings. It was named after [15]Edmund Halley, who calculated its orbit. He determined that the comets seen in 1531 and 1607 were the same object that followed a 76-year orbit. Unfortunately, Halley died in 1742, never living to see his prediction come true when the _comet_ returned on Christmas Eve 1758. _Halley's __Comet_ put on bright shows in 1835 and in 1910. Then in 1984 and 1985, five [16]spacecraft from the USSR, Japan and Europe were launched to make a rendezvous with _Halley's __Comet_ in 1986. One of NASA's deep space satellites was redirected to monitor the solar wind upstream from Halley. Only three comets have ever been studied by spacecraft. _Comet_ Giacobini-Zinner was studied in 1985, _Comet_ Halley in 1986, and CometGrigg-Skjellerup on July 10th, 1992. The nucleus of Halley is ellipsoidal in shape and measures approximately 16 by 8 by 8 kilometers (10 by 5 by 5 miles). _Halley's __Comet_ Statistics * [17]Perihelion distance: 0.587 AU * Orbital eccentricity: 0.967 * Orbital inclination: 162.24° * Orbital period: 76.0 years * Next perihelion: 2061 * Diameter: 16 x 8 x 8 km Animation of _Halley's __Comet_ * [18]Animation of Halley's comet from Giotto pictures. _(Courtesy A.Tayfun Oner)_ Views of _Halley's __Comet_ _Comet Halley in False Color_ This image of _Halley's_ Comets was taken during its 1986 appearance. False-color digital enhancement was used to permit measurement of slight brightness differences. _(Copyright Calvin J. Hamilton)_ _Giotto Mosaic of Halley's Comet_ This image is a mosaic of 8 images taken by the Giotto spacecraft during the Halley encounter on March 13, 1986. The nucleus dimensions are about 16 by 8 by 8 kilometers. By examining the dust jets being emitted from the nucleus, scientists were able to determine that only about 10% of the surface was active. _(Courtesy A. Tayfun Oner)_ _Ion Tail_ The well developed tail structure of _Comet_ Halley was captured in this image taken March 5, 1986. At this point in its orbit, Halley had recently passed perihelion on February 9, 1986 and was at its most active. This 10 minute exposure was recorded at Mauna Kea Observatory on IIIa-J emulsion without filters. This image shows both the ion and dust tail, with the latter stretching for over 6 degrees on the sky. _(Courtesy NASA/JPL)_ _Detachment Event_ One of the more spectacular changes recorded for Halley during an apparition was the detachment event that occurred on April 12, 1986. This 3 minute exposure was taken using the Michigan Schmidt telescope at Cerro Tololo Interamerican Observatory. The resulting image clearly shows part of the ion tail structure detached from the _comet_. At this period, the orientation of the _comet_ is such that the tail is foreshortened, with the prolonged radius vector pointing west of north. _(Courtesy NASA/JPL)_ _Ray Structure_ An example of the ray structure of Halley was captured on March 19, 1986, at the Mount Wilson/Las Campanas Observatories. This 10 minute exposure was recorded at the focus of the 100 inch telescope on Las Camapanas in Chile. The close up image, covering the inner 1 degree of the _comet_, shows a prolonged radius vector extending to the left. _(Courtesy NASA/JPL)_ _Cylindrical Map of the Nucleus of Comet Halley_ This image is a shaded relief map of the nucleus of _Comet_ 1/P Halley. It is the same map as the above image, but reprojected to the Simple Cylindrical projection. As with all maps, it is the cartographer's interpretation and not all features are necessarily certain given the limited data available. This interpretation stretches the data as far as is feasible. Halley is a particularly difficult object to map, given the nature of the data available. Many other interpretations might be possible. This relief drawing represents an attempt to show features visible on the disk in various spacecraft images, and the various ridges and hollows suggested by limb topography. _(Courtesy Phil Stooke)_ _Map of the Nucleus of Comet Halley_ This image is a shaded relief map of the nucleus of _Comet_ 1/P Halley. As with all maps, it is the cartographer's interpretation and not all features are necessarily certain given the limited data available. This interpretation stretches the data as far as is feasible. Halley is a particularly difficult object to map, given the nature of the data available. Many other interpretations might be possible. This relief drawing represents an attempt to show features visible on the disk in various spacecraft images, and the various ridges and hollows suggested by limb topography. _(Courtesy Phil Stooke)_ [19]HOME [20]Comet [21]Shoemaker-Levy 9 Background _Copyright © 1997-2001 by [22]Calvin J. Hamilton. All rights reserved._ [23]Privacy Statement. [24][LINK] http://www.solarviews.com