Traveling Sunspot Group; July 3 - 11, 2013

Tracking one of the largest sunspot groups across the Earth facing solar disk. This movie covers almost 9 days, from July 3 through almost the entire day of July 11, 2013.

Galileo was the first to study dark spots on the Sun which we call "sunspots". They typically measure about 10,000 kilometers across, which makes them on the order of the size of the Earth. They often occur in groups, and come and go. At some times the Sun has hundreds of sunspots, while at other times it may have almost none. Individual spots may last from 1 to 100 days. A large group of spots typically lasts 50 days.

As magnetic fields on the Sun rearrange and realign, dark spots known as sunspots can appear on its surface. Temperatures in the dark centers of sunspots drop to about 3700 K (compared to 5700 K for the surrounding photosphere).

They typically last for several days, although very large ones may live for several weeks. Sunspots are magnetic regions on the Sun with magnetic field strengths thousands of times stronger than the Earth's magnetic field. Sunspots usually come in groups with two sets of spots. One set will have positive or north magnetic field while the other set will have negative or south magnetic field.

The field is strongest in the darker parts of the sunspots - the umbra. The field is weaker and more horizontal in the lighter part - the penumbra.

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