Large Coronal Hole
An extensive coronal hole rotated towards Earth over several days this week (May 28-31, 2013). The massive coronal area is one of the largest we have seen in a year or more. Coronal holes are the source of strong solar wind gusts that carry solar particles out to our magnetosphere and beyond. They appear darker in extreme ultraviolet light images (here, a combination of three wavelengths of UV light) because there is just less matter at the temperatures we are observing in. Solar wind streams take 2-3 days to travel from the Sun to Earth, and the coronal holes in which they originate are more likely to affect Earth after they have rotated more than halfway around the visible hemisphere of the Sun, which is the case here. They may generate some aurora here on Earth.
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