NASA’s New Horizons spacecraft is less than three weeks from sailing through the Pluto system. What it will find there is still anyone’s guess, but images the spacecraft has already sent home are every bit as puzzling as we’d hoped.

The newest photos reveal a possible bright spot at Pluto’s polar cap. And Charon, the dwarf planet’s oversize moon, has a curious dark spot (“Who ordered that?” asked Alan Stern, New Horizons principal investigator). From Hubble images, we’ve also recently learned that Pluto’s small moons are chaotically rotating, and one of them is way too dark.

Before the spacecraft reveals any more about the system, I’d like to spend a little time discussing the