A fairly large coronal hole can be seen on today's Sun (March 13, 2012). The Diameter of the Sun is about 109 times the one of Earth. The length of today's coronal hole is about 50 Earths lined up next to each other.

Coronal holes are large regions in the corona that are less dense and cooler than surrounding areas. The open structure of their magnetic field allows a constant flow of high-density plasma to stream out of the holes. There is an increase in the intensity of the solar wind effects on Earth when a coronal hole faces us. The solar wind escaping from this coronal hole will reach Earth around March 17 to 18. High-latitude sky watchers should remain alert for "aftershock auroras" from the few solar flares and coronal mass ejections from last week and the arriving solar wind stream.

Credit: NASA SDO
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