NSF’s GONG program aids NASA’s Parker Solar Probe during its latest close encounter with the Sun
March 4, 2021
GONG, is a network of solar imagers distributed around the globe. They make use of the Zeeman effect — how light splits into multiple wavelengths under the influence of a magnetic field — to create magnetic maps of the solar surface. This video shows GONG’s magnetic maps, updated hourly, from January 12-23, 2021. The black areas represent areas where the magnetic field is pointing in towards the Sun’s surface, and white areas are where the magnetic field is pointing out into space.
The solar wind carries the solar magnetic field with it as it streams away from the Sun. But identifying precisely which regions on the Sun are the source for solar wind measured by spacecraft like Parker Solar Probe is a challenging task for several reasons: The Sun rotates, solar wind leaves the Sun at varying speeds, and strong magnetic fields near the Sun can change the solar wind’s path as it flows out.
During 2020 and in early 2021, NASA’s Parker Solar Probe completed four closest approaches to the Sun: January 29, 2020 – Perihelion #4; June 7, 2020 – Perihelion #5; September 27, 2020 – Perihelion #6, and the most recent one January 17, 2021 – Perihelion #7.
The PSP team uses GONG’s magnetic maps, along with data from NASA’s Solar Dynamics Observatory, to make predictions of which regions on the Sun are sending out material and magnetic field lines toward the spacecraft. Drawing these connections between the Sun itself and the solar wind that Parker Solar Probe is measuring directly can help scientists trace how conditions on the Sun propagate out into space.
GONG instruments provide regular observations of the photospheric magnetic fields, which were extensively used for modeling of magnetic connectivity between the solar surface to the PSP location in the heliosphere between Sun and Earth. The modeling community has repeatedly praised the zero-point-corrected GONG magnetograms as their preferred choice for modeling of the coronal and heliospheric magnetic fields.