July 4, 2005

Hubble Captures Deep Impact’s Collision with Comet

NASA's Hubble Space Telescope captured the dramatic effects of the collision early July 4 between comet 9P/Tempel 1 and an 820-pound projectile released by the Deep Impact spacecraft.

A sequence of images is available online at




Time-lapse video images are available at


The visible-light images show the comet before and after the impact. They were taken by Hubble's Advanced Camera for Surveys' High Resolution Camera.

The first of the three still images at http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/17/ shows the comet about one minute before the impact. The encounter occurred at 1:52 a.m. EDT.

In the second image, captured 15 minutes after the collision, Tempel 1 appears four times brighter than in the pre-impact photo. Astronomers noticed that the inner cloud of dust and gas surrounding the comet's nucleus increased by about 120 miles (200 kilometers) in size. The impact caused a brilliant flash of light and a constant increase in the brightness of the inner cloud of dust and gas.

The Hubble telescope continued to monitor the comet, snapping the third image in the sequence 62 minutes after the encounter. In that photo, the gas and dust ejected during the impact are expanding outward in the shape of a fan. The fan-shaped debris is traveling at about 1,200 miles an hour (1,800 kilometers an hour), or twice as fast as the speed of a commercial jet. The debris extends about 1,200 miles (1,800 kilometers) from the nucleus.

The potato-shaped comet is 8.7 miles (14 kilometers) wide and 2.5 miles (4 kilometers) long. Tempel 1's nucleus is too small even for the Hubble telescope to resolve.

Photo Credit: NASA, ESA, Paul Feldman (The Johns Hopkins University), and Hal Weaver (Johns Hopkins University Applied Physics Laboratory)

On the World Wide Web:

ESA/Hubble Information Centre