Even on a sunny day, human eyes can’t see all the light from the sun. But a new image displays some of this hidden light, including the high-energy X-rays emitted by the hottest material in the Sun’s atmosphere, with the NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR).
The observatory’s view of the Sun is actually a mosaic of 25 images, taken in June 2022.
NuSTAR’s view could help scientists solve one of the biggest mysteries about our nearest star: why the Sun’s outer atmosphere, called the corona, reaches more than a million degrees – at least 100 times hotter than its surface. This has puzzled scientists because the Sun’s heat originates in its core and travels outward. It’s as if the air around a fire were 100 times hotter than the flames.
The source of the corona’s heat could be small eruptions in the Sun’s atmosphere called nanoflares. Flares are large outbursts of heat, light, and particles visible to a wide range of solar observatories, NASA said. Nanoflares are much smaller events, but both types produce material even hotter than the average temperature of the corona. Regular flares don’t happen often enough to keep the corona at the high temperatures scientists observe, but nanoflares may occur much more frequently – perhaps often enough that they collectively heat the corona.
Although individual nanoflares are too faint to observe amid the Sun’s blazing light, NuSTAR can detect light from the high-temperature material thought to be produced when a large number of nanoflares occur close to one another. This ability enables physicists to investigate how frequently nanoflares occur and how they release energy.
The observations used in these images coincided with the 12th close approach to the Sun, or perihelion, by NASA’s Parker Solar Probe, which is flying closer to the our star than any other spacecraft in history. Taking observations with NuSTAR during one of Parker’s perihelion passes enables scientists to link activity observed remotely in the Sun’s atmosphere with the direct samples of the solar environment taken by the probe.
(Sourced from NASA)