, represented as red. NuSTAR’s relatively small field of view means it can’t see the entire Sun from its position in Earth orbit, so the observatory’s view of the Sun is actually a mosaic of 25 images, taken in June 2022.
The high-energy X-rays observed by NuSTAR appear at only a few locations in the Sun’s atmosphere. By contrast,’s XRT detects low-energy X-rays, and SDO’s AIA detects ultraviolet light – wavelengths that are emitted across the entire face of the Sun.: 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.
The Sun appears different depending on who’s looking. From left, NASA’s NuSTAR sees high-energy X-rays; the Japanese Aerospace Exploration Agency’s Hinode mission sees lower energy X-rays; and NASA’s Solar Dynamics Observatory sees ultraviolet light. Credit: NASA/JPL-Caltech/JAXA