Okay, who cut a square chunk out of our sun? This recent footage from the Solar Dynamics Observatory (SDO) feels like something out of an episode of Doctor Who, given the ‘artificial’ feel of a rectangular coronal hole and the strange visual of seeing the Sun in the ultraviolet range:
A coronal hole is an area where high-speed solar wind streams into space. It appears dark in extreme ultraviolet light as there is less material to emit in these wavelengths. Inside the coronal hole you can see bright loops where the hot plasma outlines little pieces of the solar magnetic field sticking above the surface. Because it is positioned so far south on the Sun, there is less chance that the solar wind stream will impact us here on Earth.