Spicules on the sun, as observed by the Solar Dynamics Observatory. These bursts of gas jet off the surface of the sun at 150,000 miles per hour and contain gas that reaches temperatures over a million degrees.
Credit: NASA Goddard/SDO/AIA
WASHINGTON: Scientists have long puzzled over why the Sun's outer atmosphere is hotter than its surface, but a new study says blistering jets of plasma are the cause.
New pictures from a NASA solar lab and a Japanese satellite showed how the gas-like plasma reaches torrid temperatures and travels in fountain-like jets, or spicules, that shoot up from the Sun's surface into its outer atmosphere, or corona.
"Our observations reveal, for the first time, the one-to-one connection between plasma that is heated to millions of degrees kelvin and the spicules that insert this plasma into the corona," said Scott McIntosh, a scientist at the National Centre for Atmospheric Research.
Influencing the Earth’s atmosphere
"By identifying that these jets insert heated plasma into the Sun's outer atmosphere, we gain a greater knowledge of the corona and possibly improve our understanding of the Sun's subtle influence on Earth's upper atmosphere."
The researchers gleaned the images from NASA's Solar Dynamics Observatory, which launched February 11 last year, and NASA's Focal Plane Package for the Solar Optical Telescope on the Japanese Hinode satellite.
The new instruments, and the high resolution images they were able to capture, served to eliminate old doubts about the role of spicules in the heating of the Sun's corona.
Spicules’ role previously dismissed
"Heating of spicules to millions of degrees has never been directly observed, so their role in coronal heating had been dismissed as unlikely," said lead author and solar physicist Bart De Pontieu.
The research, published in the journal Science, included scientists from Lockheed Martin's Solar and Astrophysics Laboratory, the US National Centre for Atmospheric Research, and the University of Oslo.
