A human-made craft has made contact with the Sun.
The upper atmosphere of the Sun is what the solar corona is. It was able to tell the tale and give us a wealth of never-before-seen data on the heart of our Solar System because it took in situ measurements.
The "touching the Sun" feat of theParker Solar Probe is a monumental moment for solar science and a truly remarkable feat," said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters.
"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 stars in the rest of the Universe."
The primary objective of the solar probe is to probe the solar corona. In its planned seven-year mission, it should be making 26 close approaches to the Sun, using a total of seven gravity assist maneuvers from Venus. The first to enter the corona was the April perihelion.
The Sun's magnetic field and particles were measured in the nearly five hours it took. Our estimates of these properties used to be based on external information.
The corona of the sun is so hot that it's the only place in the world where the sun's atmosphere is not hot.
There is evidence of being in the corona in magnetic field data, solar wind data, and in images. During a solar eclipse, we can see the spacecraft flying through the sun's corona.
The APL is part of the Naval Research Laboratory.
The bright features visible in the pictures are usually only seen from Earth during an eclipse. The images were taken by the Parker probe during the ninth perihelion in August.
The Sun is not a solid surface. The boundary is defined by the weak gravity and Sun's magnetic fields on the Alfvén critical surface.
Waves within the wind break away from the Sun as the solar wind emerges above this point. The surface of the Sun, composed of roiling convection cells, is far below.
We didn't know where the critical surface was or what its topography was, so one of the goals of the team was to find out more. Estimates put the critical surface at between 10 and 20 solar radii from the center of the Sun. During its trip through the corona, it dipped to as low as 18.4 solar radii.
The probe seemed to encounter the magnetic conditions of the corona intermittently, suggesting that the critical surface is wrinkled. During solar eclipses, we can see the magnetic structure known as a pseudostreamer, which is at the lower depths. We don't know why these structures are responsible for the change in the critical surface.
The pseudostreamer was quieter than the surrounding solar atmosphere. The magnetic field was more orderly and the particles were no longer buffeted by it.
There is a phenomenon known as solar switchbacks. These are Z-shaped kinks in the magnetic field of the solar wind, and they are not currently known where or how they form. We've known about switchbacks since the 1990s, but we didn't know that they were common until 2019. The probe's data showed us that there were patches.
The lower corona is where some of the switchbacks come from.
Stuart Bale of the University of California, Berkeley is the lead author on a paper on the phenomenon in press at The Astrophysical Journal. "This is what we expect from some theories, and this is where the solar wind comes from."
We still don't know how these structures formed, but with dozens more perihelions ahead, we're likely to be getting some pretty fascinating answers.
We have been observing the Sun and its corona for a long time, and we know there is interesting physics going on there to heat and accelerate the solar wind. We can't tell what that physics is.
We will get the long-awaited insights into the inner workings of this mysterious region with the arrival of theParker Solar Probe.
The research has been published.
