NASA’s audacious Parker Solar Probe has brought humanity closest to the Sun in a scientific first, after three years and five Venus flybys. The Probe had entered the Sun’s atmosphere on April 28, 2021. The achievement was announced at a press conference at the American Geophysical Meeting Fall Meeting in New Orleans this week.
It was necessary to let the intervening months pass for NASA to confirm they had actually done it — analyzing energy interactions recorded by the probe to try and mark the moment. Ultimately, the signature of the Sun’s magnetic field was the smoking gun that verified man had really, actually, touched the Sun.
Since then, the probe has encountered the Sun twice more — once in August and once in November.
The first paper detailing fresh results from the probe was published on Tuesday in Physical Review Letters, and there is another paper set to be published in The Astrophysical Journal.
The liminal space between the Sun’s atmosphere and space is called the Alfvén critical surface. Prior to the mission, physicists knew this dividing line was there, but didn’t know precisely where. Best estimates put it at 4.3 and 8.6 million miles above the surface of the Sun. But the Solar Probe complicates matters.
In April this year, the probe entered the Sun’s corona (another word for the atmosphere) at an altitude of 8.1 million miles above the surface of the Sun. And through this action, the probe confirmed the Sun’s atmosphere isn’t uniform in shape — it is not a large sphere encasing the burning orb. Rather, it flows with peaks and valleys that the probe passed through repeatedly. At its closest approach, the probe came within 6.5 million miles of the surface of the Sun.
The probe has also discovered two strange solar weather phenomena: A source of solar wind, known as switchbacks, and a pseudostreamer.
Switchbacks are streams of charged particles that escape the Sun in a zig-zag pattern. Parker’s flyby proved, for the first time, that the photosphere — or surface — of the Sun generates these solar winds.
A pseudostreamer is a name given to huge structures that come forth from the Sun. NASA compared it to the ‘eye of a storm’, because these structures are relatively calm compared to the surrounding environment.
The Parker Solar Probe wasn’t designed just to come near the Sun — it was designed to enter its atmosphere to settle the mystery of why the upper reaches of the corona are hotter than the surface of the Sun.
To do that, the probe is outfitted with a shield of carbon bricks able to withstand the unfathomably searing temperatures — up to 1.8 million degrees Fahrenheit.
To reach the Sun, the probe will go through a total of seven Venus flybys, which act like gravity slingshots to drop it close enough to the Sun to get inside the atmosphere. A flyby in January will bring the craft within the corona again. The next Venus flyby is slated for 2023.
These initial results are just the tip of the iceberg for Parker, which will eventually reach 3.83 million miles from the Sun’s surface.