May 26, 2016 – This imagery of the sun captured by NASA’s Solar Dynamics Observatory from May 17-19, 2016, shows a giant dark area on the star’s upper half, known as a coronal hole. Coronal holes are low-density regions of the sun’s atmosphere, known as the corona. Because they contain little solar material, they have lower temperatures and thus appear much darker than their surroundings.
Coronal holes are visible in certain types of extreme ultraviolet light, which is typically invisible to our eyes, but is colorized here in purple for easy viewing.
These coronal holes are important to understanding the space environment around Earth through which our technology and astronauts travel. Coronal holes are the source of a high-speed wind of solar particles that streams off the sun some three times faster than the slower wind elsewhere.
While it’s unclear what causes coronal holes, they correlate to areas on the sun where magnetic fields soar up and away, without looping back down to the surface, as they do elsewhere.
NASA’s Solar Dynamics Observatory is designed to study the causes of solar variability and its impacts on Earth. The spacecraft’s long-term measurements give solar scientists in-depth information to help characterize the interior of the sun, the sun’s magnetic field, the hot plasma of the solar corona, and the density of radiation that creates the ionosphere of the planets. The information is used to create better forecasts of space weather needed to protect aircraft, satellites and astronauts living and working in space.
SDO includes three instruments: the Extreme Ultraviolet Variability Experiment (EVE) built in partnership with the University of Colorado at Boulder’s Laboratory for Atmospheric and Space Physics (LASP), the Helioseismic and Magnetic Imager (HMI) built in partnership with Stanford University, and the Atmospheric Imaging Assembly (AIA) built in partnership with the Lockheed Martin Solar & Astrophysics Laboratory.
Goddard built, operates and manages the SDO spacecraft for NASA’s Science Mission Directorate in Washington, D.C. SDO is the first mission of NASA’s Living with a Star Program.