Sunday, November 2, 2008

The Sun

Sharp Solar Spicules

Spicules are plasma jets that shoot through the Sun's atmosphere or corona at about 90,000 kilometres 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. Numerical models and high-resolution observations from the new 1-metre Swedish Solar Telescope on La Palma and NASA's TRACE satellite now show that spicules are caused by shock waves formed when sound waves at the solar surface penetrate through a damping zone and leak into the solar atmosphere. (from Nature)

Credit both images: Swedish Solar Telescope / Lockheed Martin Solar and Astrophysics Lab.

This false-color image taken with a blue filter shows the photosphere, or visible surface, of the Sun, is taken at the same time as the image above. The scaly appearance is due to the presence of 'granules,' 1,000-km-wide patches of gas that constantly well up as a result of convection currents. According to the new spicule theory, these granules provide some of the upward kick that gives rise to spicules, (the rest being due to acoustic waves, p-modes).

Kicked up by the lush 'green' granules.

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