An Extensive Coronal Hole An extensive coronal hole dominated the solar landscape this week as seen in extreme ultraviolet light by SDO's (Aug. 23-25, 2010). The dark coronal hole reached more than halfway across the Sun and changed very little over these three days. Coronal holes are magnetically open areas from which high-speed solar wind streams out into space. They appear darker in this wavelength because there is just less of the material that is being imaged, in this case ionized iron. Since the hole has facing towards Earth, we have been getting some nice auroras from the more concentrated impact of the solar wind.