Four new papers in Nature journal published Thursday described what scientists have learned from this mission The findings on how the Sun constantly ejects material and energy will not only help scientists better understand and predict space weather around Earth, but also know the process through which stars are created and how they evolve. Most of the materials that escape the Sun are part of the solar wind these materials are a continual outflow of solar material that bathes the entire solar system.
This ionized gas, called plasma, carries with it the Sun’s magnetic field, stretching it out through the solar system in a giant bubble that spans more than 10 billion miles. Near the Earth, the solar wind appears to be in a relatively uniform flow of plasma, with occasional turbulence. However, closer to the solar wind’s source about 15 million miles from the Sun the Probe saw a complicated, active system.
Stuart Bale from the University of California, Berkeley, who is heading the Parker Solar Probe’s ‘FIELDS instrument’ section said, the complexity was mind-blowing when we first started looking at the data. This section studies the scale and shape of electric and magnetic fields.
Measurements showed quick reversals in the magnetic field of the Sun and sudden, faster-moving jets of material. The scientists also saw flips in the direction of the magnetic field, which flows out from the Sun, embedded in the solar wind. These reversals dubbed switchbacks last anywhere between a few seconds and several minutes as they flow over Parker Solar Probe.
During a switchback, the magnetic field whips back on itself until it is pointed almost directly back at the Sun. The exact source of the switchbacks isn’t yet understood, but Parker Solar Probe’s measurements have allowed scientists to narrow down the possibilities, NASA said in a statement issued Thursday.
Near the Earth, the solar wind is seen streaming directly from the Sun, straight out in all directions. However, closer to the surface of the Sun, the solar wind spins. This is because the Sun rotates as it releases the solar wind. According to the findings, for the first time, the Parker Solar Probe was able to observe the solar wind while it was still rotating.
Its solar wind instrument detected rotation starting more than 20 million miles from the Sun, and as the Probe approached its perihelion point (point in the orbit of a planet, asteroid, or comet that is nearest to the Sun), the speed of the rotation increased.
The strength of the solar wind circulation was more than many scientists had predicted earlier and it also transitioned to an outward flow more quickly than predicted.
Justin Kasper from the University of Michiganone, one of the scientists involved in the mission said, while we hoped to eventually see rotational motion closer to the Sun, the high speeds we are seeing in these first encounters is nearly ten times larger than predicted by the standard models.
Scientists have long suspected that dust particles, which are ubiquitous in the cosmos, would be heated to high temperatures by powerful sunlight, turning it into a gas and creating a dust-free region around the Sun. However, there was no way to observe this phenomenon.
Parker Solar Probe’s images show that the cosmic dust begins to thin out. The images show dust starting to thin a little over seven million miles from the Sun, and this decrease in dust continues steadily to over 4 million miles from the Sun.
At the rate of thinning, scientists expect to see a truly dust-free zone starting a little more than 2-3 million miles from the Sun, meaning Parker Solar Probe could observe the dust-free zone as early as 2020 when its sixth flyby of the Sun will carry it closer to the surface of the Sun than ever before.
The Probe also provided unprecedented detail on structures in the corona and solar wind — including coronal mass ejections, billion-tonne clouds of solar material that the Sun sends hurtling out into the solar system.
Russ Howard from the US Naval Research Laboratory, another scientist who was part of the mission said, since Parker Solar Probe was matching the Sun’s rotation, we could watch the outflow of material for days and see the evolution of structures.
As Parker Solar Probe continues on its journey, it will make 21 more approaches to the Sun at progressively closer distances, culminating in three orbits which are merely 3.83 million miles from the solar surface.
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