As Dawn slowly approaches Ceres, this dwarf planet's inexplicable white spot is increasingly coming into focus. Thanks to xkcd's Randall Munroe, we may finally have the answer.

Seriously, though — what the hell is that thing? Here's the latest clip from Dawn, in which you can see the spot at top left of Ceres.

An hour's worth of Ceres observations. Image credit: NASA/JPL Caltech/UCLA/MPS/DLR/IDA