Image of the Month - March 2005

Seven sisters, a comet, and an intruder

The christmas comet C/2004 Q2 (Machholz) was a fine sight in December 2004 and January 2005 for observers in the northern hemisphere. Many stargazers watched the comet slowly moving past the famous star cluster Messier 45, commonly known as the Pleiades, or "seven sisters", in the constellation Taurus, on 2005 January 7. Not missing this unique opportunity to catch a pretty comet close to this well-known cluster, a number of astrophographers also took spectacular images of the comet approaching M 45.

Comet C/2004 Q2 (Machholz) and the Pleiades
Credit & Copyright: Waldemar Skorupa,, Germany

A number of astrophographers in Europe noted a faint, unexpected intruder in their images - among them was Waldemar Skorupa. In his image shown above, a faint, long trail of an unknown object can be seen northeast (upper-left) of the comet, west (right) of the Pleiades cluster. A check of the position of the fast moving object against artificial satellites and known asteroids came up empty. Fortunately, Skorupa provided a set of three exposures with the mysterious trail, so Bill Gray was able to calculate a reliable orbit for that object. It turned out to be a satellite or upper stage rocket booster left in a geostationary transfer orbit, a rather eccentric orbit (e=0.724), with a low perigee (~350km above the Earth's surface) and a apogee in the geostationary ring, about 36.000km high. The orbital period is 630 minutes, and the inclination of 28° points toward a spacecraft started in Cape Kennedy, which is situated at a latitude of 28°.

The image above is 4 minute exposures with a Canon EOS DSLR camera and a 200mm telephoto lens. Click on the image to see the full resolution image (3504 x 2336 pixels, 1.36 MB). To see more spectacular images of this comet (and others) by Waldemar Skorupa, visit

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