Many teams of scientists are preparing themselves to profit from a rare opportunity, watching the sun during a solar eclipse. As “usual”, many studies will be on the sun’s corona, its outermost region whose abnormally high temperature is yet to be explained.
The solar atmosphere or corona, which is normally only visible from the Earth at times of total solar eclipses, has a temperature of 1—2 million degrees Celsius, the sun’s surface being at a mere 5500 degrees. The corona also emits ultraviolet and X-ray radiation, which has been observed with spacecraft such as the ESA/NASA Solar and Heliospheric Observatory (SOHO). But despite more than 60 years of study, the heating mechanism of the corona remains unknown.
The instrument used by the Anglo-Polish team, the Solar Eclipse Coronal Imaging System (SECIS), consists of a double telescope on a driven mount with fast-frame electronic cameras that will form images of the corona during eclipse totality at the rate of 40 frames per second. This is far higher than can be accomplished with spacecraft instrumentation because of telemetry restrictions.
The aim is to search for subtle oscillations in the corona’s light intensity - tell-tale signs of heating by magnetic waves, thought by many to be the main heating mechanism on local scales. The oscillations are likely to have periods of a few seconds or less.
For more information, you can head to NASA’s Eclipse Page and maybe watch the live webcast.
March 27th, 2006 | Physics