For the first time in history, a spacecraft has touched the Sun. Our Parker Solar Probe flew right through the Sun’s atmosphere, the corona. (That’s the part of the Sun that we can see during a total solar eclipse.)
This marks one great step for Parker Solar Probe and one giant leap for solar science! Landing on the Moon helped scientists better understand how it was formed. Now, touching the Sun will help scientists understand our star and how it influences worlds across the solar system.
Unlike Earth, the Sun doesn’t have a solid surface (it’s a giant ball of seething, boiling gases). But the Sun does have a superheated atmosphere. Heat and pressure push solar material away from the Sun. Eventually, some of that material escapes the pull of the Sun’s gravity and magnetism and becomes the solar wind, which gusts through the entire solar system.
But where exactly does the Sun’s atmosphere end and the solar wind begin? We’ve never known for sure. Until now!
In April 2021, Parker Solar Probe swooped near the Sun. It passed through a massive plume of solar material in the corona. This was like flying into the eye of a hurricane. That flow of solar stuff — usually a powerful stream of particles — hit the brakes and went into slow-motion.
For the first time, Parker Solar Probe found itself in a place where the Sun’s magnetism and gravity were strong enough to stop solar material from escaping. That told scientists Parker Solar Probe had passed the boundary: On one side, space filled with solar wind, on the other, the Sun’s atmosphere.
Parker Solar Probe’s proximity to the Sun has led to another big discovery: the origin of switchbacks, zig-zag-shaped magnetic kinks in the solar wind.
These bizarre shapes were first observed in the 1990s. Then, in 2019, Parker Solar Probe revealed they were much more common than scientists first realized. But they still had questions, like where the switchbacks come from and how the Sun makes them.
Recently, Parker Solar Probe dug up two important clues. First, switchbacks tend to have lots of helium, which scientists know comes from the solar surface. And they come in patches.
Those patches lined up just right with magnetic funnels that appear on the Sun’s surface. Matching these clues up like puzzle pieces, scientists realized switchbacks must come from near the surface of the Sun.
Figuring out where switchbacks come from and how they form will help scientists understand how the Sun produces the solar wind. And that could clue us into one of the Sun’s biggest mysteries: why the Sun’s atmosphere is much, much hotter than the surface below.
Parker Solar Probe will fly closer and closer to the Sun. Who knows what else we’ll discover?
