IRIS Solves The Sun's Mystery: Why Is Its Atmosphere Hot?

One of the mysteries of the Sun that scientists have been figuring out is why the outer atmosphere of the Sun, its corona, is hotter than its surface. NASA is finally on the edge of resolving this mystery through IRIS or the Interface Region Imaging Spectrograph.

NASA reports that IRIS was launched in 2013 and it is the space agency's newest Sun watcher. It monitors how energy and heat coursed through a region called the interface region. Little is known about this region. Based on the observations from IRIS, the researchers think that the corona is partly heated by "heat bombs" going off. This is triggered by blasts of energy from magnetic fields crisscrossing and realigning in the corona.

NASA's IRIS mission looks at the mysteries of 'heat bombs' and coronal heating. They have fascinated and perplexed scientists for decades. pic.twitter.com/HsKB7TzHdi

— NASA Goddard (@NASAGoddard) December 1, 2016

IRIS could analyze the solar transition region, which is the area between the Sun's surface and the corona. It also gauged the movement of hot gas in an exceptional detail. Paola Testa, the lead researcher from the Harvard-Smithsonian Center for Astrophysics, said that because IRIS can resolve the transition region 10 times better than previous instruments, they could see hot material rushing up and down magnetic fields in the low corona. This makes the corona in an intense heat.

The visible surface of the Sun has a temperature of about 5,500 degrees Celsius (9,932 degrees Fahrenheit). On the other hand, in the corona, the temperature is about 200 to 500 times hotter.

Testa said that the magnetic reconnection, in which the heat and energy released sets off heat bombs in the corona and responsible for other phenomena such as the solar flares. The findings of this discovery were published in the Astrophysical Journal, according to Science Alert.