Parker Solar Probe is a NASA robotic spacecraft launched in 2018, with the mission of repeatedly probing and making observations of the outer corona of the Sun.
One year ago, it became the closest satellite to the Sun, collecting a precious set of data from its position at the edge of the solar corona, withstanding temperatures of one million degrees.
Today, this data has allowed solar physicists to map the source of a major component of the solar wind that continually splashed the Earth’s atmosphere.
The data they gathered also revealed a strange behaviour of magnetic fields that could be sending particles to our planet.
For the first time ever, scientists can study the solar wind straight from its source, the Sun’s corona.
NASA has released four new documents that provide unknown (only theorised) features of the volatile star that presides over our solar system
The origin of the 'slow' solar wind
The Parker Solar Probe has been able to study the source of the solar wind and see how it progressively accelerates in the warm atmosphere of the Sun.
The solar wind is made up of charged particles, mainly protons and helium nuclei, which travel along the lines of the Sun’s magnetic field.
Scientists have theorised about the so-called “fast” solar wind, which has a clock speed of 500 to 1,000 kilometres per second and comes from large holes in the solar corona at the north and south poles.
The origin of the “slow” solar wind, denser and about half the speed of the “fast” solar wind, was much more unknown.
Thanks to Parker’s observations, scientists have been able to trace the solar wind and magnetic fields back to their source: the coronal holes. These are much cooler and less dense areas that the surrounding corona.
Credits: NASA / SDO
"We can see the magnetic structure of the corona, which tells us that the solar wind is emerging from small coronal holes," explains Stuart Bale of the University of California, Berkeley, lead author of an article on the new results of the probe's FIELDS experiment.
"In addition, we see impulsive activity: large jets or backslides that we believe are related to the origin of the solar wind; we see the instability of the gas itself, which generates waves.
"We are also surprised by the ferocity of the dust environment in the internal heliosphere," he added.
Turns in the magnetic field
The most unexpected part of the data was a series of somersaults in the magnetic field, which the Parker probe observed in its path.
This is the behaviour of the solar wind within Mercury's orbit, which alters the direction of the magnetic field flowing from the Sun.
During this event, the magnetic field turns on itself until it points almost directly at the Sun itself.
As the researchers explain: "It suddenly reversed 180 degrees and then, seconds to hours later, it retreated.
These observations help us understand what causes solar winds, what heats them, and also how stars work and how they release magnetic energy into their environment.
"These interruptions are probably associated with some kind of plasma jets," Bale explains. "My feeling is that these interruptions or jets are fundamental to the problem of solar wind heating.
Rotating solar wind
In one publication, researchers found surprising clues about how the Sun's rotation affects the solar wind's output flux.
The solar wind flows beyond our planet as if it were traveling in almost straight lines, or ‘radially,’(like spokes on a bicycle wheel) from the Sun in all directions.
But the Sun rotates as it releases the solar wind, and before it is released, the solar wind is expected to synchronise with the Sun's rotation.
"The solar wind comes out of the coronal hole in a smooth flow. But in addition, there are jets; by the time everything reaches Earth, it is mixed," explains Bale.
Parker also observed the first direct evidence that the dust begins to dilute about 11 billion kilometres from the Sun, an effect that has been theorised for nearly a century, but until now was impossible to measure.
Strange explosions of energetic particles
Finally, Parker's Integrated Scientific Research of the Sun (ISʘIS) energetic particle instruments have measured a rare type of particle explosion with a particularly high proportion of heavier elements, suggesting that both types of events may be more common than scientists thought.
Solar energetic particle events are important because they can arise suddenly and cause weather conditions near the Earth that are potentially harmful to astronauts.
What is the purpose of the Parker probe data?
As explained in a NASA statement, the information Parker has discovered about how the Sun constantly expels material and energy can help scientists predict the weather in the space around our planet and help understand the process by which stars are created and evolve.
More specifically, this information will be vital to protecting astronauts and technology in space, for example, for the imminent mission to the Moon Artemis, to be launched in 2024, which will send the next man and first woman to our satellite.
The results will be discussed and compared in conversations at the next American Geophysical Union meeting in San Francisco beginning December 8.
During his initial overflights, Parker studied the Sun from a distance closer to the Sun than Mercury. And it will come even closer in future flights.