19P/Borrelly Comet

Astronomical specifications: Discovery  December 28, 1904 Orbital characteristics: Distance from Sun   km Perihelion   (106 km) Aphelion   (106 km) Inclination   deg Eccentricity   Orbital periode rond Sun  6.91 years Main orbital speed   km/s Inclination to Sun equator   deg Physical characteristics: Dimensions   km Radius   km Surface area   km² Volume   106 km³ Mass   1024 kg Density   g/cm³ Equatorial surface gravity   m/s² Escape velocity   km/s Rotation period   days Surface temperature   K Axial tilt   deg Atmospheric composition

Courtesy of NASA/JPL/Caltech

Discovery:

Historical Highlights:

• The comet was widely observed during January 1905, with the maximum magnitude reaching about 9 early in the month. In addition, the coma diameter was typically near 2 arc minutes, while a tail length of 10 arc minutes was reported. The comet was followed until May 25, at which time the magnitude had declined to 14.5. R. G. Aitken (Lick Observatory, California, USA) computed an elliptical orbit early in February which indicated an orbital period of 7.30 years. By the time observations ceased astronomers had determined the comet passed perihelion on 1905 January 17. The perihelion distance was determined as 1.395 AU, and the orbital period was 6.91 years.
• The comet was also scutinized by the Hubble Space Telescope (HST) during the 1994 apparition. Philippe Lamy (Laboratoire d'Astrophisique de Marseille CNRS, France) was the principal investigator of the HST comet nucleus detection project.
• An especially important note about the 2001 apparition is that this comet became only the second comet to be photographed up close by a space probe, when Deep Space 1 flew about 1350 miles from the nucleus on September 22. Pictures of the nucleus revealed it measured 5 miles long and about 2.5 miles wide. As the probe approached the comet a sharply defined jet about 60km long was detected extending toward the sun. As the probe moved closer this jet was resolved into three columns or jets, and at its closest, the probe revealed the jets were emanating from bright, smooth patches on the surface. The primary jet appears to emanate from the rotation axis. It was mentioned that there were signs that the jets were eroding away at the surface and creating basins. It was suggested that since the erosion is occuring along the rotation axis, this might eventually cause the comet to split.

External links:

• Cometography.com: Comet 19P/Borrely description.

Borrelly missions: