The visible surface of the sun has a temperature of 10,000 degees F. (5,538 degrees C.) One might think that moving away from the inferno would cool things down, but that’s not the case. Instead, the sun’s upper atmosphere, or corona, sizzles at millions of degrees – a temperature 200 to 500 times higher than that of the roaring furnace below.
For more than a half-century, astronomers have tried to figure out what causes the coronal heating. Now, new observations by NASA’s IRIS spacecraft suggest that “heat bombs” are going off in the sun’s outer atmosphere, helping to explain what makes it so mysteriously hot.
Bottom line: NASA video on coronal hearing – why the sun’s outer atmosphere is so mysteriously hot.
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. Today, as Lead Editor at EarthSky.org, she helps present the science and nature stories and photos you enjoy. She also serves as one of the voices of EarthSky on social media platforms including Facebook, Twitter and G+. She and her husband live in Tennessee and have two grown sons.