Alphonse Louis Nicolas Borrelly (Marseilles, France) discovered this comet during a routine search for comets on 1904 December 28. It was then situated within Cetus and was moving northward. Borrelly described it as 1 to 2 arcmin across, with a small, faint nucleus.
An especially important note about the 2001 apparition is that this comet became only the second comet to be photographed up close by a space probe, when Deep Space 1 flew about 1350 miles from the nucleus on September 22. Pictures of the nucleus revealed it measured 5 miles long and about 2.5 miles wide. As the probe approached the comet a sharply defined jet about 60km long was detected extending toward the sun. As the probe moved closer this jet was resolved into three columns or jets, and at its closest, the probe revealed the jets were emanating from bright, smooth patches on the surface. The primary jet appears to emanate from the rotation axis. It was mentioned that there were signs that the jets were eroding away at the surface and creating basins. It was suggested that since the erosion is occuring along the rotation axis, this might eventually cause the comet to split.
False color image from 12 x 30 sec. taken December 2, 2001
This image is the highest resolution image obtained during the flyby of the space probe Deep Space 1 on 2001 September 22. Image courtesy of NASA/JPL/Caltech