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 2016 transit of Mercury is upon us! With fine weather predicted across a large swathe of the British Isles, many will enjoy clear skies for at least some of this 7½-hour event. But if you don’t have a suitably equipped telescope, or are unable to attend any of the transit-viewing activities organised nationwide, you can still view the phenomenon online.