NASA’s Parker Solar Probe could finally find the answer to why is the Sun’s outer atmosphere hotter than its fiery surface.
The sun’s corona, the outermost layer of the star’s atmosphere, can reach temperatures of 2 million degrees Fahrenheit. But the surface of the sun reaches only about 10,000 Fahrenheit which is significantly lower than that of the corona.
Scientists at the University of Michigan may already have the answer but they need NASA’s probe to confirm it.
They theorize that the heating is due to small magnetic waves traveling back and forth within the zone.
In about two years the Parker Solar Probe could become the first to enter the “zone of preferential heating” above the surface of the sun. This will allow scientists to test their theory.
You Might Like This:
These so-called “Alfvén waves” reach the “Alfvén point” where they can no longer travel back to the Sun.
“When you’re below the Alfvén point, you’re in this soup of waves,” stated Justin Kasper, a professor of climate and space sciences at the University of Michigan and the principal investigator behind the mission. “Charged particles are deflected and accelerated by waves coming from all directions.”
In this “zone of preferential heating,” temperatures rise overall, but strangely, some individual elements heat up to different temperatures. Some heavier ions are superheated until they’re ten times hotter than the hydrogen that is everywhere in this area. That is hotter than the core of the sun.
These high temperatures cause the Sun’s atmosphere to grow many times larger than the diameter of the star itself. These temperatures also create the extended corona that is visible during solar eclipses.
“With Parker Solar Probe we will be able to definitively determine through local measurements what processes lead to the acceleration of the solar wind and the preferential heating of certain elements,” Kristopher Klein, co-author of the study from the University of Arizona, said in a statement.
“The predictions in this paper suggest that these processes are operating below the Alfvén surface, a region close to the Sun that no spacecraft has visited, meaning that these preferential heating processes have never before been directly measured,” he said.
Why is this important?
Understanding this mystery would allow scientists to better predict solar weather, which can pose serious threats to life on Earth. Scientists first need to find where the heating of the sun’s outer atmosphere begins and ends.
Once within this zone, the probe will help determine what is causing the heating by directly measuring the magnetic fields and particles there.
“Whatever the physics is behind this superheating, it’s a puzzle that has been staring us in the eye for 500 years,” Kasper said. “In just two more years Parker Solar Probe will finally reveal the answer.”