Comet 73P/Schwassmann-Wachmann 3
from Palomar Observatory

Press release: Palomar Observes Broken Comet

The movie above was produced from a sequence of images showing fragment R of Comet 73P/Schwassmann-Wachmann 3. The images were taken using the 200-inch Hale Telescope the night of May 2-3, 2006 by Eran Ofek of the California Institute of Technology (Caltech) and Bidushi Bhattacharya of Caltech's Spitzer Science Center.

The comet was discovered by Arnold Schwassmann and Arno Arthur Wachmann in 1930. It has been observed many times over the decades but was found to have broken up into four fragments in 1995. It has since further split into dozens, if not hundreds, of pieces.

A sequence of images showing the piece of the comet known as fragment R has been assembled into a movie. A portion of the last 15 frames can be seen above. The movie shows the comet in the foreground against distant stars and galaxies which appear to streak across the images. Because the comet was moving at a different rate across the sky than the stellar background, the telescope was tracking the comet's motion and not that of the stars. Fragment R and many smaller fragments of the comet are visible as nearly stationary objects in the movie. In all, 16 new fragments were discovered as a part of the Palomar observations.


  • small animated gif (7.5 mb)
  • full animated gif (30 mb)
  • quicktime movie (17 mb)
  • A single frame from near the end of the sequence

    The images used to produce the movie were taken over a period of about one hour and 34 minutes when the comet was approximately 17 million kilometers (10.6 million miles) from Earth. The comet is making a close approach to Earth (astronomically speaking) in May, 2006 giving astronomers a front-row seat to the comet's break up. Closest approach for any fragment of the comet occurred on May 12, 2006 when a fragment was just 5.5 million miles from Earth. This is more than 20 times the distance to the Moon. There is no chance that the comet will hit Earth.

    All images were taken through a filter that passed red light. In each image North is up and East is to the left.

    The Palomar observations were coordinated with observers using the Spitzer Space Telescope which imaged the comet's fragments K through P in the infrared. The infrared images, combined with the visible-light images obtained using the Hale Telescope will give astronomers a more complete understanding of the comet's break up.

    Additional Palomar images of fragments of Comet 73P/Schwassmann-Wachmann 3:

    Fragment BF as observed on May 01, 2006. The comet and its tail can be seen in the upper right. The telescope was guiding on fragment BF instead of the stars. As such, the stars appear as streaks.

    Fragment B as observed on May 01, 2006.

    Fragment C as observed on May 01, 2006.

    Click to enlarge
    The above figure indicates the relative position of 59 of the known cometary fragments, as identified using the JPL/Horizons database for May 04 from 0800 - 1200 UT. Lines of motion for all fragments are indicated. For clarity only some of the fragments have been labeled.

    Images are copyrighted by their respective owners. Contact the photographers directly for permission to use their images for any purpose.