9P/ Tempel 1 Comet

Astronomical specifications: Discovery  April 3, 1867 Orbital characteristics: Distance from Sun   km Perihelion   (106 km) Aphelion   (106 km) Inclination   deg Eccentricity   Orbital periode rond Sun  5.68 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

This image was obtained on 2005 May 1.87 UT with the 8-inch Celestron Schmidt camera and a SXV H9 CCD camera. The image was a combination of 8 separate images and had a total exposure time of 28 minutes. Credit: 2005 by Michael Jäger (Austria)

Discovery:

Historical Highlights:

• The comet was very well placed during the 1867 discovery apparition thanks to the closest approach to Earth (0.568 AU) and the perihelion (1.562 AU) occurring on May 15 and 24, respectively. Subsequently, there were numerous observations which ultimately covered nearly 5 full months. The comet was last detected on August 27.8 by J. F. J. Schmidt (Athens), at which time it was too faint for position measurements. The comet was then 1.30 AU from Earth and 1.81 AU from the sun. The comet was still about 4 arc minutes across in early May. Total magnitude estimates were not typically made during this period in history, but estimates of the magnitude of the nucleus, or at least the most brilliant, condensed portion of the coma, reached a maximum of 10.5 shortly before mid-May.
• Conditions for the comet's recovery in 1873 were very good, with the circumstances being only marginally worse than in 1867. The comet was recovered on April 4, by E. J. M. Stephan (Marseille, France). The comet remained under observation until July 1.
• The comet passed 0.55 AU from Jupiter during 1881 and the orbital period was increased to 6.5 years. This situation caused the comet to be observable only at every other return. In addition, the perihelion distance was increased from 1.8 AU to 2.1 AU, making the comet an even fainter object. Subsequently, the comet was not seen at its next returns. Photographic attempts during 1898 and 1905 also failed to recover the comet.
• During the early days of 1967, J. Schubart (Astronomisches Rechen-Institut) began his investigation with an unpublished orbit by Guntrum Schrutka von Rechtenstamm (Vienna University Observatory) and integrated the orbit through the upcoming apparition. He predicted the perihelion date would be January 12.55.
• The 1972 return was very favorable. Schrutka von Rechtenstamm's orbit was now published and Schubart provided ephemerides in a couple of major publications. Roemer and L. M. Vaughn recovered the comet on January 11 from Steward Observatory. The comet became widely observed and reached a maximum magnitude of 11 during late May. The comet was last seen on July 10. This apparition proved that the single image found in 1967 was indeed 9P/Tempel 1.
• This comet was selected as the target of the Deep Impact mission. First proposed back in 1999, the mission was launched on 2005 January 12. Deep Impact released the "Impactor" on 2005 July 3 and this crashed into the comet on July 4. The predicted crater was expected to be the size of a typical sports stadium, but the debris which sprayed out from the impact effectively blocked the crater from the spacecraft's view. Nearly every major observatory on our planet observed the event, as did amateur astronomers. The event was also studied by several satellites and space probes, including the Hubble Space Telescope, the Chandra X-ray Observatory, and Rosetta, the later of which was heading toward a rendezvous with another comet and provided valuable observations of 9P/Tempel 1 from a different observing angle. Another satellite, the Submillimeter Wave Astronomy Satellite, which had been put to sleep on 2004 July 21 after completing its mission, was reactivated to monitor water output during the Deep Impact event.

External links:

• Cometography.com: Comet 9P/Tempel 1 description.

Tempel 1 missions: