This image shows the nucleus of comet Tempel 1 and the nucleus of comet Hartley 2. (The comets are placed next to each other for comparison; they are nowhere near each other in space.) As you can see, comets come in all shapes and sizes.
Tempel 1 is five times larger than Hartley 2. Jets are easily seen coming off Hartley 2 but extensive processing was required to see jets on Tempel 1.
Tempel 1 is 7.6 kilometers (4.7 miles) in the longest dimension. Hartley 2 is 2.2 kilometers (1.4 miles) long.
NASA's Deep Impact spacecraft took both images. When the spacecraft took the Hartley 2 image, it was called the EPOXI mission.
Image credit: NASA/JPL-Caltech/UMD
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