This is a false-colour composite image of Comet 9P/Tempel 1 taken during the night of 4/5 May with the EMMI instrument on the NTT telescope. It shows the comet at 100 million kilometres away from Earth. The coma extends more than 30 thousand kilometres from the comet nucleus.
North is up, the exposure time is 30 seconds in the V filter (associated to the blue channel), 45 seconds in R (green) and 30 seconds in I (red). The images were obtained by M. Baes and M. Castillo, on behalf on the international team led by Olivier Hainaut (ESO, Chile).
As the images in the various filters were obtained one after the other, and as the comet is moving in front of the background objects, the two stars visible in this image appear as sequences of coloured dots. The comet itself appears only very softly coloured, as its dust reflects almost uniformly the light from the Sun.