Huge Dark Area on the Sun

A huge dark area across the top of the sun, a coronal hole, a region where the magnetic field is open to interplanetary space, sending coronal material speeding out in what is called a high-speed solar wind stream.

The high-speed solar wind originating from this coronal hole, imaged here on Oct. 10, 2015, by NASA’s Solar Dynamics Observatory, created a geomagnetic storm near Earth that resulted in several nights of auroras. This image was taken in wavelengths of 193 Angstroms, which is invisible to our eyes and is typically colorized in bronze.

source NASA