Tau Bootis A is a Sun-like white-dwarf star about 51 light-years from Earth. Its magnetic field changes polarity once every year as opposed to the 11 years it takes our Sun. While astronomers don’t really know why this is the case, they have a pretty interesting hypothesis: Tau Bootis A has a giant planet orbiting really close to it, and its gravitational field could be ‘dragging’ on the outer, convective layers of its host star to speed up its polarity reversals. Here’s an explanation of how this could work. It’s pretty fascinating that while we had the Sun’s cycle figured, just the second star we study that shows this behaviour defies most of our expectations.