For the first time, humans have “touched” the sun, as the Parker Solar Probe broke through the solar atmosphere.
The probe, launched in 2018 to study the Sun, has been inching closer and closer to this point, and in April, it finally passed through the plasma corona and to the surface. The surface of the sun is a toasty 10 million degrees.
The Sun doesn’t actually have a solid surface; it’s a ball of gas, made up of hydrogen, helium, and a few other elements. When scientists talk about ‘touching’ the sun, they mean Parker flew through its superheated atmosphere, called the corona, that’s made up of solar material that stays close to the sun through gravity and magnetism. The boundary Parker crossed to fly through the corona is known as the Alfvén critical surface.
"Parker Solar Probe ‘touching the Sun’ is a monumental moment for solar science and a truly remarkable feat," Thomas Zurbuchen, the associate administrator for the Science Mission Directorate at NASA Headquarters in Washington, said in a press release. "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.”
As the probe cut through the corona on one of its flybys, it transmitted back to Earth images of “coronal streamers,” structures where particles slowed down because of strong magnetic forces. This was the first time these “pseudostreamers,” as NASA called them, were seen up-close; they’re visible from Earth during solar eclipses, but hadn’t been viewed at their origin before.
Parker is just getting started with these close-passes through the Sun’s atmosphere. The next close flyby is scheduled for next month.
Updated 12/16 10:08 a.m. to correct an error in the definition of the solar surface.