Parker Probe’s path through solar blast yields unparalleled space weather insights

Jeremy Rehm

Parker Solar Probe passed through a coronal mass ejection (CME)

These fierce eruptions can expel magnetic fields and sometimes billions of tons of plasma at speeds ranging from 60 to 1,900 miles (100 to 3,000 kilometers) per second. When directed toward Earth, these ejections can bend and mold our planet’s magnetic field, generating spectacular auroral shows and, if strong enough, potentially devastate satellite electronics and electrical grids on the ground.

Cruising on the far side of the Sun just 5.7 million miles (9.2 million kilometers) from the solar surface — 22.9 million miles (36.8 million kilometers) closer than Mercury ever gets to the Sun — Parker Solar Probe first detected the CME remotely before skirting along its flank.

The spacecraft later passed into the structure, crossing the wake of its leading edge (or shock wave), and then finally exited through the other side.

In all, the Sun-grazing spacecraft spent nearly two days observing the CME, providing physicists an unparalleled view into these stellar events and an opportunity to study them early in their evolution.

“This is the closest to the Sun we’ve ever observed a CME,” said Nour Raouafi, the Parker Solar Probe project scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, which built the spacecraft within NASA’s timeline and budget, and currently manages and operates the mission. “We’ve never seen an event of this magnitude at this distance.”

From NASA - Parker Observes Powerful Coronal Mass Ejection by Ashley Hume

“These interactions between CMEs and dust were theorized two decades ago, but had not been observed until Parker Solar Probe viewed a CME act like a vacuum cleaner, clearing the dust out of its path,” said Guillermo Stenborg, an astrophysicist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and lead author on the paper. APL built and operates the spacecraft.

This dust is made up of tiny particles from asteroids, comets, and even planets, and is present throughout the solar system. A type of faint glow called zodiacal light, sometimes visible before sunrise or after sunset, is one manifestation of the cloud of interplanetary dust.

The CME displaced the dust all the way out to about 6 million miles from the Sun – about one-sixth of the distance between the Sun and Mercury – but it was replenished almost immediately by the interplanetary dust floating through the solar system

In-situ observations from Parker were critical to this discovery, because characterizing dust dynamics in the wake of CMEs is challenging from a distance. According to the researchers, Parker’s observations could also provide insight into related phenomena lower down in the corona, such as coronal dimming caused by low-density areas in the corona that often appear after CMEs erupt.