NASA’s Parker Solar Probe captured the finest-ever view of the origin of the solar wind, which is the name given to the stream of energized particles expelled from the star.
The spacecraft observed some weird spikes in the wind, where particles accelerate and switch the direction of the wind’s magnetic field. It also spotted the wind orbiting the Sun faster than anticipated, which could suggest that the understanding we have so far of how stars’ rotation decelerates as they age, is wrong.
The discoveries, noted in four papers published in the journal Nature on December 4th, could help scientists grasp a better idea and prepare for times when the solar wind is especially violent and takes down radio and other communications as it spreads over Earth.
Rendezvouses at a Close Distance
These findings are the first the Parker Solar Probe, which launched last year and managed three complete orbits around the Sun, sent back to Earth.
The Parker Solar Probe is slowly approaching the Sun at a closer distance as it orbits it. The most recent rendezvous took place in September of this year, and the next is scheduled to occur in January.
“We’re observing in a regime that we’ve only speculated about before now,” says Sarah Gibson, a solar physicist at the National Center for Atmospheric Research in Boulder, Colorado.
The spacecraft is observing the energy that blazes the Sun’s outer atmosphere, or corona, and speeds up the solar wind. Even though researchers can analyze the solar wind as it approaches Earth, doing so is similar to attempting to study the birthplace of a waterfall from midway of the cliff over which it falls, Stuart Bale, a plasma physicist at the University of California, Berkeley, explained.
He said: “If you want to know the source, you have to get up there and get closer — is it coming from one hole in the ground? From a bunch of seams in the rocks? Is there a sprinkler system up there?”
NASA‘s solar probe calculated the area of the solar wind originating from a small hole in the Sun’s atmosphere close to the equator. This is the closest peak yet at one of the solar wind’s birthplace. The vehicle also discovered that when the wind reaches the space, parts of it accelerated in high-velocity spikes.
Justin Kasper, a space scientist at the University of Michigan in Ann Arbor, said that these might as well be considered rouge waves. Within these waves, the velocity of the solar wind two-folded, as the stream was so powerful that it transiently inverted the wind’s magnetic field.
The spacecraft passed through over 1,000 of these spikes every time it approached the Sun, but experts don’t understand yet what causes them.
Another interesting discovery is how rapidly the solar wind orbits the Sun as the star rotates. Computerized models show that the wind streams in this direction at a velocity of few kilometers per second. However, the Parker Solar Probe calculated it moves at approximately 35 to 50 kilometers per second.
The findings have significant consequences. Scientists are now being aware that the wind is spinning at a different speed than previously believed, which could help them enhance predictions of when a precarious solar explosion might get to Earth.
The discoveries also imply that the solar wind is carrying more energy away from the Sun than expected, so the star’s orbit might be decelerating more quickly than earlier believed. If so, scientists might need to reconsider their theories about how other stars in the Universe mature.