Solar Wind Stream Source (January 19, 2007)

The Earth passed through a stream of solar wind that flowed out of this expansive coronal hole (seen in lower central area of the Sun in still on January 14, 2006). Coronal holes appear as a dark area of the Sun when viewed in ultraviolet light (as it is here) and in X-rays. Since coronal holes are 'open' magnetically, strong solar wind gusts can escape from them and carry solar particles out to our magnetosphere and beyond. Solar wind streams take several 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 (see 6-day video clip).

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. The SOHO CELIAS proton monitor saw an increase in solar wind speed from ~ 300 km/s (as low as it usually gets) to nearly 700 km/s associated with this hole. There were reports that sky-watchers in Wisconsin had seen mild auroral displays caused by this coronal hole and it is likely that more aurora will be observed. This is our magnetic connection to the Sun

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.