Spiky Spicules on the Sun (August 9, 2007)
Hi-res TIF image (1.1M)
A close up view of the top of the Sun as seen in profile shows thousands of little spurts, like small blow torches, shooting out all over the Sun. The movie shows just an average day's worth of this kind of activity as seen from the STEREO spacecraft (Ahead) in extreme ultraviolet light (August 3, 2007). These spurts are called spicules. With STEREO's 2048×2048 image resolution and an image every 10 minutes, we can zoom in on features like this with no distortion. Spicules are plasma jets that shoot through the Sun's atmosphere or corona at about 90,000 kilometers per hour. Discovered in 1877 by Angelo Secchi, they remain largely unexplained, in part because observations are difficult for objects with a brief life (about 5 minutes) and relatively small size (diameters of just 300 miles / 500 kilometers). They are caused by shock waves formed when sound waves at the solar surface leak into the solar atmosphere. More than 100,000 spicules occur at any given time on our star's surface.
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 firstname.lastname@example.org.