Throwing Shade on a Comet

On Valentine's Day last year--Feb. 14, 2015--the Rosetta space probe passed an astonishing six kilometers above the surface of the comet 67P/Churyumov-Gerasimenko. Mind you, the comet is only about four km end to end, so this was a very, very close shave. The images it took at the time are amazing, but not for the obvious reason. Cooler to me was that the flyby was done in such a way that the Sun, spacecraft, and comet were in a perfect line. So what? Well, that means the spacecraft could see it...