June 7, 2005 | David F. Coppedge

Understanding the Sun – Not

Exclusive  The star we understand best should be the closest – our own – right?  Despite a revolution in solar observations, there is much we don’t know about Ol’ Sol.  That was the flavor of a talk by Dr. Alan Title (Stanford) at the Jet Propulsion Laboratory on Monday.  At one point, he showed a picture of magnetic loops extending far from the solar surface without dissipating, and growing and combining from small to large scales, and remarked, “Anybody familiar with basic E&M [electromagnetic theory] knows that that is impossible.”  Other mysteries involve the rotation of the convecting layer, lack of symmetry between the poles, and even the origin of the magnetic field.  The bottom line was that we have more questions than answers over the last decade.
    In the Q&A, someone asked if lessons learned from solar astrophysics are getting to the stellar astronomers.  The answer was a qualified yes.  It could be better but is fairly good, he said; but if we can’t understand convection in our own star, that’s a warning and a challenge to postulating about the fluid mechanics of other stars.
    Another question was whether we still learn anything useful from solar eclipses.  Yes, he said (although the discoveries tend to be more fun these days).  We can put coronagraphs in orbit, but they are hard to keep steady.  “The moon is a very good occulting disk,” he said.

A point well taken: if we cannot understand a star that looms large in our sky and is up all day, how much can we express confidence in our theories about points of light trillions of miles away?  To gain more appreciation of our sun, and our occulting moon, see the film The Privileged Planet.

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Categories: Solar System

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