Sun's Super-Hot Shell Cooked by Plasma Jets


Physicists who train their thoughts on the sun have long been perplexed by why its outer atmosphere is millions of degrees hotter than the surface. While theories abound, no direct observations have been made of the mysterious processes that heat the sun's atmosphere ... until now.

With the help of some state-of-the-art technology, a team of scientists thinks it has discovered an important piece of the puzzle. The results of the new study suggest that the scorching heat of the solar atmosphere is continuously replenished by jets of plasma that scream upward from the surface of the sun at supersonic speeds.

These plasma jets, called spicules, are "long, elongated fin features at the edge of the sun," Bart De Pontieu, the study's lead researcher, told The motion of the heated spicules could explain how the sun's atmosphere, or corona, is a few million degrees hotter than the surface, which has a temperature of about 10,800 degrees Fahrenheit (6,000 degrees Celsius).

"The gas or plasma is originally pretty cool, but as the spicules are propelled upwards, some fraction of that gas gets heated to a few million degrees," said De Pontieu, a solar physicist at the Lockheed Martin Solar and Astrophysics Laboratory in Palo Alto, Calif.