Figure A


Figure B


Figure C
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This composite image of the Sun includes high-energy X-ray data from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) shown in blue; lower energy X-ray data from the X-ray Telescope (XRT) on the Japanese Aerospace Exploration Agency's Hinode mission shown in green; and ultraviolet light detected by the Atmospheric Imaging Assembly (AIA) on NASA's Solar Dynamics Observatory (SDO) shown in red.

Figure A shows the isolated NuSTAR data with a grid added to indicate the Sun's surface; Figure B shows the isolated Hinode data; and Figure C shows the isolated SDO data.

NuSTAR's relatively small field of view means it can't see the entire Sun from its position in Earth orbit, so Figure A is a composite of 25 images, which were taken by the observatory in June 2022. NuSTAR sees high-energy X-rays that appear at only a few locations, where the hottest material is present in the Sun's atmopshere. By contrast, Hinode's XRT and SDO's AIA detect detect wavelengths emitted across the entire face of the Sun. The hotspots observed by NuSTAR might be caused by collections of nanoflares, or small outbursts of heat, light, and particles from the Sun's surface that subsequently heat the atmosphere. Individual nanoflares are too faint to directly observe amid the Sun's blazing light.

NuSTAR launched on June 13, 2012. A Small Explorer mission led by Caltech in Pasadena, California, and managed by JPL for NASA's Science Mission Directorate in Washington, it was developed in partnership with the Danish Technical University (DTU) and the Italian Space Agency (ASI). The telescope optics were built by Columbia University, NASA's Goddard Space Flight Center in Greenbelt, Maryland, and DTU. The spacecraft was built by Orbital Sciences Corp. in Dulles, Virginia. NuSTAR's mission operations center is at the University of California, Berkeley, and the official data archive is at NASA's High Energy Astrophysics Science Archive Research Center. ASI provides the mission's ground station and a mirror data archive. Caltech manages JPL for NASA.