The aurora borealis is usually visible only way up north, but over the past 18 months, shimmering curtains of pink and green light have filled night skies across much of North America, at times offering dazzling displays as far south as Texas and Hawaii.
These widespread light shows have been caused by especially strong blasts of solar wind—electrically charged particles shot out from the sun at incredible speeds. The strength of these is down to the sun reaching the peak of its solar cycle, a period of increased solar storms that happens every 11 years. Although the cycle’s peak has just passed, stronger than usual storms—and unusually widespread auroras—are expected to last into 2026.
This is one example of what scientists call “space weather,” which deals with the interaction between the sun and the Earth. Not all the consequences of space weather are pretty, and some are outright dangerous. But the physics behind it are pretty cool. Let’s check it out!
Blowin’ in the Wind
You might think of the sun as a great ball of fire—but it’s not. (Fire is a chemical reaction between oxygen and carbon.) What the sun is, really, is a giant nuclear fusion reactor. In the core, protons are smashed together under extreme pressure. These protons stick together to create the nucleus of a helium atom, with two protons and two neutrons. (Two of the protons decay into neutrons).
S 001