NASA has announced that the Parker Solar Probe has become the first spacecraft to fly through the sun’s upper atmosphere, or corona. In April, it passed within 15 solar radii (about 6.5 million miles) from the surface of the Sun in a region where magnetic fields dominate solar conditions. “The Parker Solar Probe Touching the Sun is a historic moment for solar science and a truly remarkable achievement,” said Thomas Zurbuchen, associate administrator for NASA.
The Sun has an extremely hot atmosphere called a corona (which can only be seen from Earth during a solar eclipse) linked to it by gravity and magnetic fields. At a certain limit called the Alfvén critical surface, materials are able to escape these forces and become part of the solar wind, permanently cutting off their contact with the Sun.
Scientists have estimated that the corona lies between 10 to 20 solar radii from the surface of the Sun, or about 4.3 to 8.6 million miles. The Parker Solar Probe detected the required magnetic conditions and particles for the corona at about 18.8 solar radii, or about 8.1 million miles. It passed in and out of bounds several times, proving that the critical surface of Alfvén had spikes and valleys rather than as a smooth ball.
Within that region, the probe encountered features called pseudostreamers, or huge structures rising above the surface of the Sun visible during a solar eclipse. Flying through the objects is like “flying in the eye of a storm” because of the quieter conditions and the slower the particles, NASA said.
It also provided observations that may help scientists learn where the “reversals” or kinks in the solar wind are located. It detected bursts of recoil as it passed close to the sun, and scientists were able to trace it back to the visible surface. Specifically, they find that some types of “fast” switching form in the magnetic pathways that arise between convective cells on the Sun’s surface.
Not only has the probe cut the closest path to the Sun, but it is traveling at the fastest speed of any man-made object ever, currently around 430,000 miles per hour. The next near-pass will occur in January 2022, when scientists will try to determine exactly how the permutations and other solar phenomena form. “Such measurements from the corona will be critical to understanding and predicting extreme space weather events that can disrupt communications and harm satellites around the Earth,” NASA wrote.
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