The Rosetta probe has sent back the first color photo of the comet it's been closely trailing since August. Previously only photographed in black and white, comet 67P/Churyumov-Gerasimenko appears in the new snapshot in hues recalling red clay.
The photo was taken using one of the two cameras that make up Rosetta's OSIRIS imaging system, which can capture wavelengths of light in the visible, near infrared and near ultraviolet ranges. The dual-camera OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) uses one narrow angle camera to take high-resolution images of the comet itself, while the other camera takes wide angle views to capture the dust and gas hovering above its surface. Each is outfitted with about a dozen filters that selectively include or exclude certain wavelengths.
This photo was taken with the narrow angle camera and the help of 11 optical filters. It is unclear at this time whether it shows the comet's "true colors," or whether the filters imbued the image with an artificial tan.
Previously, the European Space Agency clarified that its black and white pictures don't accurately reflect actual color, stating that "comets are blacker than coal" and explaining that images from Rosetta's navigation camera (NAVCAM) are "grey-scaled according to their brightness with additional contrast adjustments to bring out the full range of features."
This photo was not taken with the NAVCAM, but that doesn't mean the colors are necessarily those one would see with the naked eye.
Questions about where 67P falls on the rainbow should be answered, at the latest, on Dec. 18, when researchers discuss the color patterns observed on the comet's surface at the American Geophysical Union meeting in San Francisco.