The Nucleus of Comet Tempel 1

Looking over the list of planets, moons, and smaller bodies I posted so far, I realized I didn't have an image of a comet yet. There's a couple of reasons for my neglect. One is that, by and large, our imaging of comets is not particularly good. If they're active comets, they're difficult to get close to, because of the inconvenient way they throw out lots of vapor, dust, and even small particles of icy material that can be rough on a spacecraft and its instruments. Also, there's never been a mission to orbit a comet, and it's orbital missions that return the best photos. (That'll change in 2014, when Rosetta arrives at comet 67P / Churyumov-Gerasimenko.) The other reason, I think, is that, when seen up close, comets are -- how do I say this? -- I think they are ugly. Here is a gorgeous photo of a truly ugly object, comet 9P / Tempel 1, as seen by Deep Impact. This is a new color composite, assembled by Daniel Machá?ek using a color snapshot I put together plus lots of images from the impactor spacecraft plus lots of work.…