This image of the Sun was taken on August 2, 2012, at 2:20 pm. The telescope has a Calcium-K filter, which filters out all of the colors of the Sun except for one shade of deep violet.
This particular color reveals features of the chromosphere, or atmosphere, of the Sun. It is an especially good color for tracking the magnetic activity of stars. Sunspots look dramatic in this color, as do the brighter plages (or clouds) around and above them.
The Calcium-K color of light is sometimes used to estimate the ages of stars. Younger stars have more magnetic activity.
Telescope: Lunt 60mm Calcium-K
Camera: Lumenera SKYnyx2-2M
Image Number: WEB12563-2012
Credit: Photo by Geneviève de Messières, Smithsonian Public Observatory Project
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