NASA’s Nuclear Spectroscopic Telescope Array Reveals Hidden Light Shows on the Sun

Some of the hottest spots in the Sun’s atmosphere appear in the NuSTAR telescope’s X-ray view.

Even on a sunny day, human eyes can’t see all the light our nearest star gives off. 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, as observed by NASAEstablished in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. Its vision is "To discover and expand knowledge for the benefit of humanity." Its core values are "safety, integrity, teamwork, excellence, and inclusion." NASA conducts research, develops technology and launches missions to explore and study Earth, the solar system, and the universe beyond. It also works to advance the state of knowledge in a wide range of scientific fields, including Earth and space science, planetary science, astrophysics, and heliophysics, and it collaborates with private companies and international partners to achieve its goals.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR). While the observatory typically studies objects outside our solar system – like massive black holes and collapsed stars – it has also provided astronomers with insights about our Sun.

In the composite image above, NuSTAR data is represented as blue and is overlaid with observations by the X-ray Telescope (XRT) on the Japanese Aerospace Exploration Agency’s Hinode mission, represented as green, and the Atmospheric Imaging Assembly (AIA) on NASA’s Solar Dynamics Observatory (SDO), 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, HinodeThe Hinode Satellite was launched in 2006 and is on a mission to study our Sun. The Hinode satellite includes three science instruments — an X-ray Telescope, a Solar Optical Telescope and an Extreme Ultraviolet Imaging Spectrometer.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>Hinode’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.

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. 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 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.

More About the Mission

On June 13, 2012, the Caltech-led Small Explorer mission, NuSTAR, was launched. It is managed by JPL on behalf of NASA’s Science Mission Directorate in Washington. The project was developed in collaboration with the Danish Technical University (DTU) and the Italian Space Agency (ASI), with the telescope optics built by Columbia University, NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and DTU, while the spacecraft was assembled by Orbital Sciences Corp. in Dulles, Virginia. Mission operations are overseen by the University of California, Berkeley, while NASA’s High Energy Astrophysics Science Archive Research Center serves as the official data archive. ASI provides both the ground station and mirror data archive, with JPLThe Jet Propulsion Laboratory (JPL) is a federally funded research and development center that was established in 1936. It is owned by NASA and managed by the California Institute of Technology (Caltech). The laboratory's primary function is the construction and operation of planetary robotic spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA's Deep Space Network. JPL implements programs in planetary exploration, Earth science, space-based astronomy and technology development, while applying its capabilities to technical and scientific problems of national significance.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>JPL being managed by Caltech for NASA.