(January 13, 2026)

Coining the term “near-Earth astrophysics,” Fasel has devoted much of his career to investigating solar-terrestrial interactions between the Sun and Earth, using the aurora borealis to obtain clues regarding the coupling mechanisms between the solar wind and the Earth’s terrestrial magnetic field.

“Stars have winds,” says Fasel. “And this includes our Sun. While solar wind is a relatively continuous stream of particles that interact with the Earth’s magnetic field, the Sun can also produce powerful solar storms. These storms expel billions of charged particles [plasma] coupled to magnetic fields, called coronal mass ejections, which bang up into the Earth’s magnetic field.”

The Earth’s magnetic field lines, Fasel explains, “act like wires” on which these particles travel down into the Earth’s upper atmosphere, specifically the ionosphere. The aurora is an end result of this interaction, where high-energy electrons collide with oxygen to produce green light, while those of lower energy produce a raspberry-red color.