Between 4 and 6 September, NASA’s Solar Dynamics Observatory spacecraft captured extreme ultraviolet images of a large, well-developed “hole” in the Sun’s corona followed by the formation of another, larger hole nearby. Coronal holes are dark, cooler regions of the Sun’s outer atmosphere associated with open magnetic field lines where electrically charged particles making up the solar wind readily stream out into space. Brighter areas in this view are regions where magnetic activity is strong.
