Full disk
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The solar chromosphere at large
Uccle Solar Equatorial Table, 80 mm H-alpha telescope
The Sun on the morning of April 2, 2017 at 08:00 UT as seen through the 80-milimeter H-alpha telescope of the Uccle Solar Equatorial Table of the Royal Observatory of Belgium (USET, ROB).
The H-alpha line shows the solar chromosphere as a delicate pattern of short and narrow fibrils outlining the borders of supergranular cells in the quiet Sun (the roundish cells that can be observed all over the solar disk), long fibrils connecting the opposite polarity sunspots of an active region (revealing the magnetic field lines like iron filings around a magnet), flares (localized explosive events that release huge amounts of energy), and prominences off-disk (they can be observed on-disk too, in which case they are referred to as "filaments").
Here, an M-class flare is visible at the far right of the image in active region NOAA 12644. This image is a result of lucky-imaging using the best 25% of 40 frames taken in a 10-second window, deconvolved to restore image details. To better show the faint prominences, the off-disc structures have been processed separately and are intensity inverted.
Image credit: Emil Kraaikamp (Royal Observatory of Belgium)