Observations Around Solar System With Parker Solar Probe’s 7th Solar Encounter – Watts Up With That?

Observations Around Solar System With Parker Solar Probe’s 7th Solar Encounter – Watts Up With That?


March 5, 2021

Celestial geometry presented a special opportunity during Parker Solar Probe’s seventh solar swing, which culminated in its next solar approach, or perihelion, on January 17, 2021. The configuration of this particular orbit placed the Parker solar probe on the same side of the sun as the earth – meaning that terrestrial observatories could observe the sun and its solar wind emanation from the same perspective as Parker’s. This follows a similar observation campaign in winter 2020.

“Along with the global scientific community, the Parker Solar Probe team can’t wait to see this new data,” said Nour Raouafi, researcher on the Parker Solar Probe Project at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. “Combining this with contributions from observatories around the world will help us put Parker’s observations in a broader context and create a complete picture of the phenomena observed in the solar atmosphere.”

Read on for snapshots of some of the missions that saw the sun and solar system observed by Parker Solar Probe during the seventh solar encounter.


Credits: JAXA / NASA / Hinode

These images were taken with the X-ray telescope (XRT) on board the Hinode spacecraft of the Japan Aerospace Exploration Agency and NASA. XRT observes the sun using X-rays, a high-energy light that reveals the extremely hot material in the sun’s atmosphere called the corona. These images from XRT were taken on January 17th when Parker Solar Probe was closest to the sun. Scientists can use the images from XRT with Parker Solar Probe’s direct measurements of the sun’s surroundings to better understand how the sun’s corona can cause changes in the space environment further away from the sun.

Solar dynamics observatory

Credits: NASA / SDO

NASA’s Solar Dynamics Observatory (SDO) constantly observes the sun from its position in orbit. SDO captures images of the sun in extreme ultraviolet light – a type of light that is invisible to our eyes – and visible light and magnetic maps of the sun. The data from SDO can help scientists understand the relationship between conditions on the Sun and measurements from solar vehicles like Parker Solar Probe in the solar wind.

These images were taken at 211 angstroms, a wavelength of extreme ultraviolet light emitted by material at about 3 million degrees Fahrenheit. This wavelength highlights both active regions – seen as bright points in the image – as well as coronal holes, areas with an open magnetic field on the sun, from which high-seed solar wind can flow into space. Coronal holes appear as dark areas in this wavelength of light.


Credits: NASA / IRIS

NASA’s Interface Region Imaging Spectrograph (IRIS) captures images of the lower regions of the sun’s atmosphere in ultraviolet light as well as spectra that break down how much light is visible over different wavelengths. These images, captured on January 17, show an active region on the sun, an area of ​​intense and complex magnetic fields that is prone to explosions of light and solar material. This particular active region was selected for IRIS observations based on model predictions that indicated that magnetic field lines from this region might be the ones that Parker Solar Probe would cross and measure during its solar encounter.

The images pass through different wavelengths of light – corresponding to views of different heights above the sun’s surface – in order to reveal features in different regions of the sun’s structure. These images show features from the sun’s surface to a few thousand miles above the chromosphere, a region of the solar atmosphere associated with the extensive solar atmosphere behind it.


Black and white map of the sun from GONG dataCredits: Global Oscillation Network Group / National Solar Observatory / AURA / NSF

The National Science Foundation’s Global Oscillation Network Group (GONG) is a network of solar imagers distributed around the world. They use the Zeeman effect – how light splits into several wavelengths under the influence of a magnetic field – to create magnetic maps of the sun’s surface. This video shows GONG’s hourly updated magnetic maps from January 12-23, 2021. The black areas represent areas where the magnetic field is pointing towards the sun’s surface, and white areas are areas where the magnetic field is pointing into space.

When the solar wind flows out of the sun, it carries the solar magnetic field with it. Identifying exactly which regions on the sun are the source of solar wind measured by spacecraft like Parker Solar Probe is a challenging task for several reasons: the sun is rotating, solar wind is leaving the sun at different speeds, and strong magnetic fields in the Proximity to the sun can change the path of the solar wind as it flows out.

The Parker Solar Probe team uses GONG’s magnetic cards, along with data from NASA’s Solar Dynamics Observatory, to make predictions about which regions on the sun are sending lines of material and magnetic field to the spaceship. By drawing these connections between the sun itself and the solar wind, which Parker Solar Probe directly measures, scientists can track how conditions on the sun spread into space.


A trio of NASA’s THEMIS spacecraft – short for time history of events and macroscale interactions during substorms – orbits the earth to measure particles as well as electric and magnetic fields in near-earth space. THEMIS data will help researchers unravel the intricate factors that determine the response of near-Earth space to dynamics in the Earth’s magnetic field, changes in the sun’s ever-emitting solar wind, and activity on the sun.

These measurements were taken on January 20th by THEMIS-E, one of the spacecraft in orbit around the earth. It takes about two to three days for the solar wind to traverse the tens of millions of miles from the Sun to Earth, i.e. the sun January to affect the near-earth space.

Stacked measurement diagrams show changing conditions throughout the dayStacked measurement diagrams show changing conditions throughout the dayCredits: NASA / THEMIS

THEMIS-E started the day traveling through the Van Allen Radiation Belts – concentric bands of charged particles nested in the Earth’s magnetic field – as they neared Earth. THEMIS-E then migrated back out through the radiation belt. Both passages through the radiation belts are reflected at the beginning of the day in the areas of intense coloring in the lower left part of the diagram.

In the morning, THEMIS-E left the Earth’s magnetic field and entered the magnetic sheath – the region just outside the extreme sun-directed limit of the Earth’s magnetic field, in which solar wind accumulates when it collides with the Earth’s magnetic field. During the day, gusts in the solar wind temporarily pushed the boundaries of the magnetosphere to Earth, which means that THEMIS-E has repeatedly exited and re-entered the magnetic divide. For about 15 hours – until its orbit brought it back into the magnetosphere late in the day – THEMIS-E alternately observed the undisturbed solar wind outside the magnetic sheath and the stacked solar wind inside the magnetic sheath. The undisturbed solar wind observed by THEMIS-E was slightly slower than usual, but also about twice as dense as typical solar wind – observations also confirmed by the Advanced Composition Explorer and NASA’s wind spaceship, which orbit further upstream between the sun and earth .

By Sarah Frazier
NASA Goddard Space Flight Center, Greenbelt, Md.

Last updated: March 5, 2021

Editor: Sarah Frazier

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