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Hubble Images Comet Tempel 1 Just Before Deep Impact Probe Arrives

NASA's Hubble Space Telescope has snapped an image of Comet 9P/Tempel 1 just days before the Deep Impact spacecraft is scheduled to rendezvous with the comet. This image, taken on the morning of June 30, 2005, shows an undisturbed and quiet comet. This Advanced Camera for Surveys (ACS) Wide Field Camera (WFC) image of Tempel 1 shows a slightly larger view of the comet than was seen in Hubble images taken with the ACS/High Resolution Camera, which were released last week.

The Deep Impact Probe finally arrived at the comet this morning after a seven-month flight. Images just before and just after the impact were taken by a multitude of telescopes on the ground and in space. The space-based cameras viewing the probe-cometary impact are the Deep Impact spacecraft, as well as those aboard three of NASA's Great Observatories -- the Hubble Space Telescope, the Spitzer Space Telescope and Chandra X-ray Satellite. Several detectors will continue to view the comet in the days and weeks to come for a glimpse of any affect of the impact.

The observations by the Deep Impact camera and the Hubble telescope complement each other. The camera aboard the Deep Impact spacecraft provided a close-up view of the comet, from about 300 miles away. From its distance 80 million miles away, Hubble captured a broader view of the encounter. The difference between the views of Hubble and the Deep Impact spacecraft is like that between a satellite image of a hurricane and a photo from the center of the storm.

Comets are thought to be "dirty snowballs," porous agglomerations of ice and rock that dwell in the frigid outer boundaries of our solar system. Periodically, they make their journey into the inner solar system as they loop around the Sun. Comets are relics of our early solar system, chunks of leftover material from the formation of the planets. Locked beneath the comet's surface is pristine material that astronomers want to study to learn how our solar system formed.

The comet's name is derived from the amateur astronomer Ernst Wilhelm Leberecht Tempel of Marseilles, France, who discovered Comet Tempel 1 in 1867. Little is known about the history of the comet, except that it is a periodic comet that orbits the Sun every 5.5 years. It has probably made more than 100 passages through the inner solar system. Comet Tempel 1 is a potato-shaped object that is 8.7 miles (14 kilometers) wide and 2.5 miles (4 kilometers) long.

The ACS/WFC image is a composite of data taken with blue and red filters onboard Hubble. A quiescent comet is seen in this pre-impact image along with elongated star trails. As the telescope was locked on the movement of the comet, the background stars left small trailed arcs during the time the exposures were taken.

Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)
Acknowledgment: P. Feldman (JHU), L. McFadden (University of Maryland), H. Weaver (JHU APL)