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.
The alignment of Sun, Moon and Earth resulted in a partial solar eclipse on 13 September, visible only from the southern tip of Africa and Antarctica. But as NASA’s Solar Dynamics Observatory, or SDO, kept up its constant watch on the Sun, its view of the eclipse was photobombed by the Earth — the first time that an Earth eclipse and a lunar transit have coincided.