A NASA spacecraft has made a surprising find on the surface of the sun: a square-shaped "hole" in the star's outer atmosphere.
The dark square on the sun, known as a "coronal hole," is an area where the solar wind is streaming out of the sun at superfast speeds. NASA captured a video of the sun's square-shaped coronal hole between Monday and Wednesday (May 5-7) using the powerful Solar Dynamics Observatory (SDO).
The coronal hole appears dark in the NASA view because there is less material emitting light in the ultraviolet range of the spectrum used to make the video, according to a NASA video description. [Biggest Solar Storms of 2014 (Photos)]
"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," SDO officials wrote in the video description. "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."
NASA's sun-watching Solar Dynamics Observatory is just one of a fleet of spacecraft keeping a close watch on the weather on Earth's parent star. In 2013, the sun experienced its peak activity of its 11-year solar weather cycle.