Animation courtesy of NASA/Walt Feimer, Max-Q Digital.

Journey Beneath a Sunspot

This animation takes us on a fanciful flight beneath the surface of the Sun. At the start, we are looking down at an active region on the photosphere, the visible "surface" of the Sun. Looping magnetic field lines, shown as silvery-white tubes, rise out of one sunspot and descend back into another. Sunspots are darker areas on the Sun's surface where extremely powerful magnetic fields inhibit the inflow of hot plasma, making the sunspots somewhat cooler and dimmer than their surroundings.

Zooming in, our make-believe flight takes us beneath the surface of the photosphere to the upper reaches of the Sun's interior. Starting in the 1960s, solar astronomers have used a technique called helioseismology to study the interior of the Sun. By observing the motion of pressure waves on the Sun's surface, they can infer properties of the solar interior beneath. On our imaginary flight, we see clusters of looping magnetic field lines rise from the depths and "break" the surface, creating sunspots at the photosphere.

Rising once again above the surface, we see one loop of a magnetic flux "rope" narrow and then get "pinched off" in a process called magnetic reconnection. Like an overstretched rubber band that snaps, this reconnection process releases lots of energy. This animation shows this energy release producing a solar flare - a sudden local brightening of the photosphere below - and a coronal mass ejection (CME) - a swarm of energetic particles blasting off into space.

Right-click (Windows) or Option-click (Mac) on one of the following links to download a copy of this video in either the QuickTime (6.1 MB) or MPEG (5.9 MB) format.

Last modified December 30, 2009 by Randy Russell.

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