How NASA's Parker Solar Probe "Touches" The Sun!

Parker Solar Probe is the 1st spacecraft to touch the sun

In the first time, a spacecraft has literally touched the sun. Scientists made the announcement this week (December 14, 2021) at the American Geophysical Union meeting in New Orleans. They said the Parker Solar Probe flew through the sun’s upper atmosphere, its wispy corona, on April 28, 2021. The corona is that fiery-looking outer layer of the sun that appears around the moon’s silhouette during total solar eclipses. Parker Solar Probe has been sampling the corona’s particles and magnetic fields. It’s been making discoveries more distant spacecraft can’t make. For example, the solar wind is a stream of charged particles released from the sun’s corona. Parker Solar Probe found zigzag structures in the solar wind that scientists are calling the switchbacks. Cool!

On the same day, the peer-reviewed Physical Review Letters has published the results of Parker Solar Probe’s first venture into the sun’s upper atmosphere. The Astrophysical Journal  also accepted the results for publication.

Thomas Zurbuchen, the associate administrator for the Science Mission Directorate at NASA Headquarters in Washington, he is said:

Touching the sun is a monumental moment for solar science and a truly remarkable feat. Not only does this milestone provide us with deeper insights into our sun’s evolution and its impacts on our solar system, but everything we learn about our own star also teaches us more about as the stars in the rest of the universe.

In addition, Nour Raouafi of Johns Hopkins Applied Physics Laboratory said:

Flying so close to near the sun, Parker Solar Probe now senses conditions in the magnetically dominated layer of the solar atmosphere – the corona – that we never could before. We see evidence of being in the corona in the magnetic field data, solar wind data, and visually in images. We can actually see the spacecraft flying through coronal structures that can be observed during a total solar eclipse.

What does touching the sun looks like? For one thing, as Parker Solar Probe passed through our sun’s corona, or wispy outer atmosphere, it flew by structures called coronal streamers. These structures are the bright features moving upward in the upper images above, and angled downward in the lower row. They are the streamers visible around the dark moon silhouette during total solar eclipses. And now our robot emissary – Parker Solar Probe – has touched these streamers, and measured them, for the first time.  Image via NASA/ Johns Hopkins APL/ Naval Research Laboratory.

Reaching the Alfvén critical surface:

NASA launched Parker toward the sun in 2018. As Parker circled  closer during several flybys, scientists looked for indications that it had reached the Alfvén critical surface. The Alfvén critical surface is the point that marks  as end of the solar atmosphere and the beginning of the solar wind. The sun doesn’t have a solid surface, it does have a boundary. The boundary is the point at which solar material bound to the sun by gravity and magnetic forces ends.

Solar material energetic enough to cross the Alfvén critical surface becomes the solar wind, dragging the magnetic field lines with it. If Once the material crosses this boundary, the wind is moving too fast to ever travel back to the sun, severing the connection.

Scientists estimated the Alfvén critical surface was somewhere between 10 and 20 solar radii from the surface of the sun. This is equal to 4.3 to 8.6 million miles (7 to 13.8 million km) from the sun. When Parker finally spiraled close enough to the sun  detect that it had crossed the Alfvén critical surface, it was 18.8 solar radii (around 8 million miles or 13 million km) above the solar surface. For the first time, on April 28, 2021, Parker entered the solar atmosphere.

Justin Kasper of BWX Technologies Inc. and the University of Michigan, said:

We were fully expecting that, sooner or later, we would like encounter the corona for at least a short duration of time. But it is very exciting that we’ve already reached it.

Parker Solar Probe: 1st spacecraft to touch sun

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Kelly Kizer WhittD

December16, 2021

Parkerlar Probe is the 1st spacecraft to touch the sun

For the first time, a spacecraft has literally touched the sun. Scientists made the announcement that week (December 14, 2021) at the American Geophysical Union meeting in New Orleans. They are said the Parker Solar Probe flew through the sun’s upper atmosphere, its wispy corona, on April 28, 2021. The corona is that fiery-looking outer layer of the sun that appears around the moon’s silhouette during total solar eclipses.   Parker Solar Probe has been sampling the corona’s particles and its magnetic fields. It’s been making discoveries more distant spacecraft can’t make. For example, the solar wind is a stream of charged particles released from the sun’s corona layer. Parker Solar Probe found zigzag structures in the solar wind that's are scientists calling switchbacks. Cool!

On the same day, the peer-reviewed Physical Review Letters published the results of Parker Solar Probe’s first venture into the sun’s upper atmosphere. The Astrophysical Journal has also accepted the results for publication.

Thomas Zurbuchen, the associate administrator for the Science Mission Directorate at NASA Headquarters in Washington, said:

Touching the sun is a monumental moment for solar science and a truly remarkable feat.

In addition, Nour Raouafi of Johns Hopkins Applied Physics Laboratory said:

Flying so close to the sun, Parker Solar Probe now senses conditions in the magnetically dominated layer of the solar atmosphere – the corona – that we never could before. We see evidence of being in the corona in magnetic field data, solar wind data, and visually in images. We can actually see the spacecraft flying through coronal structures that can be observed during a total solar eclipse.

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Black background with white streaks running left to right.

What does touching the sun look like? For one thing, as Parker Solar Probe passed through our sun’s corona, or wispy outer atmosphere, it flew by structures called coronal streamers. These structures are the bright features moving upward in the upper images above, and angled downward in the lower row. They are the streamers visible around the dark moon silhouette during total solar eclipses. And now our robot emissary – Parker Solar Probe – has touched these streamers, and measured them, for the first time. Image via NASA/ Johns Hopkins APL/ Naval Research Laboratory.

Reaching the Alfvén critical surface

NASA launched Parker toward the sun in 2018. As Parker circled closer and closer during several flybys, scientists looked for indications that it had reached the Alfvén critical surface. The Alfvén critical surface is the point that marks the end of the solar atmosphere and the beginning of the solar wind. While the sun doesn’t have a solid surface, it does have a boundary. The boundary is the point at which solar material bound to the sun by gravity and magnetic forces ends.

Solar material energetic enough to cross the Alfvén critical surface becomes the solar wind, dragging magnetic field lines with it. Once the material crosses this boundary, the wind is moving too fast to ever travel back to the sun, severing the connection.

Scientists estimated the Alfvén critical surface was somewhere between 10 and 20 solar radii from the surface of the sun. This is equal to 4.3 to 8.6 million miles (7 to 13.8 million km) from the sun. When Parker finally spiraled close enough to the sun to detect that it had crossed the Alfvén critical surface, it was 18.8 solar radii (around 8 million miles or 13 million km) above the solar surface. For the first time, on April 28, 2021, Parker entered the solar atmosphere.

Justin Kasper of BWX Technologies Inc. and the University of Michigan, said:

We were fully expecting that, sooner or later, we would encounter the corona for at least a short duration of time. But it is very exciting that we’ve already reached it.

Part of sun with glowing layers around it and Parker Solar Probe on the edge.

Artist’s concept shows NASA’s Parker Solar Probe. It is the 1st spacecraft to touch the sun. Image via NASA.

The peculiarities of the sun’s border

Parker Solar Probe discovered that this boundary – the Alfvén critical surface – isn’t smooth and round. The edge has wrinkles. The spacecraft passed through spikes and valleys as it dove in and out of the boundary. Parker got as close as just under 15 solar radii (around 7 million miles or 11 million km) from the sun’s surface. In this region it passed through a pseudostreamer, a feature in the corona. Pseudostreamers are towering structures that rise above the sun’s surface that we can see during solar eclipses.

Being inside the pseudostreamer was like being inside the eye of a hurricane. The conditions were quieter and slower, easing the barrage of particles on the spacecraft. In this region, magnetic fields were they dominate force over particles, providing proof that Parker was inside the Alfvén critical surface.

Parker only spent a few hours in the sun’s corona. But the spacecraft will continue to spiral closer, aiming for a distance of 8.86 solar radii (3.83 million miles or 6.1 million km) from the surface. Its next flyby, in January 2022, should dip Parker into the corona again. Nicola Fox of NASA said:

I’m excited to see what Parker finds as it repeatedly passes through the corona in the years to come. The opportunity for new discoveries is boundless.

Parker Solar Probe is part of NASA’s Living with a Star program to explore aspects of the Sun-Earth system that directly affect life and society. The Living with a Star program is managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, manages the Parker Solar Probe mission for NASA and designed, built, and operates the spacecraft.