The sun's magnetic field causes sunspots and solar storms like the one that sent auroras over the world this month.
The origin of the sun's magnetic field has puzzled astronomers for centuries, since Italian astronomer Galileo first observed sunspots in the early 1600s and noticed how they changed.
A Wednesday Nature publication by interdisciplinary researchers proposed a novel theory. They believe the sun's magnetic field comes from the surface, contrary to earlier study.
Their model could help scientists grasp the 11-year solar cycle and forecast space weather, which can impair GPS and communication satellites and stun night sky viewers with auroras.
This work proposes a new hypothesis for how the sun's magnetic field is generated that better matches solar observations and could be used to predict solar activity,
said Daniel Lecoanet, an assistant professor of engineering sciences and applied mathematics at Northwestern University's McCormick School of Engineering and a member of the Center for Interdisciplinary Exploration and Research in Astrophysics.
We want to predict whether the next solar cycle will be strong or weak. The prior models (thinking the solar magnetic field is formed deep within the Sun) could not accurately predict the next solar cycle's strength or weakness, he added.
Sunspots let scientists monitor the sun. They start explosive flares and ejections that unleash light, solar material, and energy into space. The recent solar storm indicates that the sun is reaching “solar maximum”—its 11-year cycle peak of sunspots.
We suspect the 11-year sunspot cycle is reflecting a cycle in the Sun's internal magnetic field since the number of sunspots tracks with it, Lecoanet added.
It's hard to observe the sun's magnetic field lines looping through its atmosphere to build a more complex magnetic web than Earth's. Scientists use mathematical models to understand the sun's magnetic field.