Coronal holes appear as dark areas of the corona when viewed in ultraviolet light and in X-rays (seen here in the upper half of the Sun in ultraviolet light). This coronal hole area is one of the larger ones seen over the past year. Since coronal holes are 'open' magnetically, strong solar wind gusts can escape from them and carry solar particlesout 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. This same hole may reappear when the Sun rotates this area around again in about two weeks.

The magnetic field lines in a coronal hole open out into the solar wind rather than connecting to a nearby part of the Sun's surface. Coronal holes are responsible for the high-speed solar wind streams that sweep through the plane where the planets orbit -- and thus have a direct affect on "space weather" near the Earth. Thus, people living at the higher latitudes probably experienced mild geo-effective storming for these few days in the form of aurora displays.

Previous Picks of the Week

SOHO began its Weekly Pick some time after sending a weekly image or video clip to the American Museum of Natural History (Rose Center) in New York City. There, the SOHO Weekly Pick is displayed with some annotations on a large plasma display.

If your institution would also like to receive the same Weekly Pick from us for display (usually in Photoshop or QuickTime format), please send your inquiry to steele.hill@gsfc.nasa.gov.