The idea of a moon having its own moon sounds strange but fascinating. People often wonder if a smaller object […] ...

Io, moon of Jespiter Jupiter, is famously volcanically active. It has more than 400 active volcanoes, over an area the size of Asia. Some of the volcanic mountains are taller than Mount Everest.

Times listed are from The Sky This Week by Astronomy magazine, calculated for 40°N, 90°W. Central Wisconsin observers can expect sunrise, ...