This image of an active Sun comes from a hydrogen-alpha telescope at the Phoebe Waterman Haas Public Observatory. It was taken at 11:48 am ET on November 15, 2013.
This kind of telescope shows the atmosphere of the Sun. This view illustrates that the largest sunspots are not necessarily the most active. A sunspot, appearing as a dark spot on the Sun, is a region of intense magnetic activity. The largest sunspot on the Sun on this day, toward the left, is significantly larger than the Earth. However, it has a simple, untwisted magnetic field, and shows little magnetic activity around it.
The two swarms of smaller sunspots toward the lower center are much more magnetically active. The many small sunspots are joined by complex, twisted magnetic fields. They are surrounded and even obscured by brighter clouds of gas called plages. These clouds can brighten dramatically when a flare occurs nearby.
Solar scientists watched all of these sunspots with great interest. The group to lower right, AR1893, produced a powerful X-class flare several days later, just before rotating out of view.
Telescope: 100mm Lunt hydrogen-alpha
Camera: Lumenera SKYnyx 2-2M