Coronal holes are areas where the Sun’s corona is darker, and colder, and has lower-density plasma than average. In this case it looks like a giant hole in the middle of the sun. These were first found when X-ray telescopes in the Skylab mission were flown above the Earth’s atmosphere to reveal the structure of the corona. An extensive coronal hole rotated towards Earth recently (May 28-31, 2013). The massive coronal area is one of the largest 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. 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.
Watching the solar corona is like observing the patterns of clouds in the sky.
Want to join in? Save this to your To-dos or mark as Done.