Sunspots form due to magnetism, according to new theory

Just in time for the sun’s busy season, scientists believe they may have figured out just what causes sunspots to appear on the surface of our very own star.

It’s been known for some time that the spots appear darker because the area where the sunspot is located is cooler, giving it a darker appearance–but scientists haven’t been able to figure out what causes the cooling that results in a sunspot.

According to new research conducted at the University of Hawaii, the reason behind this may have to do with the formation of hydrogen molecules. The formations are believed to decrease the pressure on the surface, which allows for magnetic fields to form. When the magnetic field strengthens, it inhibits the flow of heat to the area, resulting in a sunspot.

The vast majority of the sun’s atoms–about 90 percent–are hydrogen, but since the sun is so hot, hydrogen mostly only exists on the surface in the form of single ionized atoms in gaseous form. In the early formation of sunspots, however, the surface temperature can cool to the point where hydrogen atoms are able to bond together, forming a hydrogen molecule.

“The formation of a large fraction of molecules may have important effects on the thermodynamic properties of the solar atmosphere and the physics of sunspots,” said Dr. Sarah Jaeggli, a scientists who conducted the research while studying at the University of Hawaii.