Comet Cardinal and M38, April 12, 2009. This small green comet (shown in the lower right of the photo) was discovered by Canadian astronomer Rob Cardinal, a researcher at the University of Calgary. Its green colour comes from fluorescing CN (cyanogen) and C2 molecules. On the evening of April 12 the comet was just a degree away from M38, a large open cluster of stars shown here in the upper left. The bright star on the lower right, about half a degree from the comet is the red giant Sigma Aurigae. On this night Comet Cardinal was roughly 261 million km from Earth.

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