The world, Ceres
A: Oh, look! Something shiny!
Really. Several years ago astronomers noticed what looked like flashing signals from the largest asteroid, which was twice in its history briefly classified as a full planet and is now considered a "dwarf planet" like Pluto. Since Ceres isn't particularly icy, the sun couldn't be reflecting off of ice.
Turns out, the Dawn spacecraft has observed, that the substance in the craters that's been sending false Morse Code signals to us is probably salt deposits at its bottom. Anyway, here is a neat new picture of Ceres taken by Dawn.