NASA Detects Dark Hole in Sun
On July 11th 2016, a NASA spacecraft captured the image of a massive dark blotch on the Sun's face, reports Discover Magazine. The eerie image can make one wonder whether the shadowy blemish is going to spread across the solar disc, blacking out the Sun. That's a fanciful idea, but not something that is going to happen.
The patch of darkness is a coronal hole on the Sun, explains NASA. While that doesn't sound reassuring, the "holes" are the natural effects of activity in the Sun's corona - its atmosphere. Although it is easy to think of the Sun as sphere of uniformly bright plasma, in reality, the solar corona is as active as Earth's own atmosphere - and the coronal effects are visible using extreme ultraviolet light (EUV).
Because of fluctuations in the solar magnetosphere, a wide swathe of the corona may become cooler and less dense with plasma. Against the Sun's hotter, denser irradiance, this region can appear very dark. That is what creates a coronal hole. Solar particles are escaping from such an area, and thus discharging a fast solar wind.
An interesting sidenote: The aurora borealis of the far northern sky is made by the solar wind interacting with the Earth's magnetosphere. The sighting of a coronal hole may be a sign that the northern lights will be making an appearance - just something to keep in mind.
The new coronal hole imagery comes from the Solar Dynamics Observatory (SDO), a NASA spacecraft that has been on a mission to observe solar activity since launching in 2010. The SDO is equipped with highly-advanced imaging and sensory instruments, such as the Atmospheric Imaging Assembly (AIA), which continuously scans the Sun's chromosphere and corona with filtering through seven EUV channels.
The SDO mission is part of NASA's Living With a Star (LWS) research program that seeks to investigate how interactions of the Sun-Earth system can influence human life and society.