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A broad-spectrum “white-light” solar filter captures images of the Sun’s photosphere and excels in revealing visual details of sunspots - areas where a strong magnetic field concentration inhibits convection from the Sun’s interior and therefore are cooler and appearing darker than the surrounding “surface.”
A hydrogen-alpha filter focuses on a much narrower portion of the spectrum to reveal details in the Sun’s chromosphere (the layer above the photosphere). The filter is effective in showing filaments - long, dense and relatively cooler (therefore darker) threads of plasma. These ribbons of ionized gas are suspended above the photosphere by magnetic forces. When in profile on the limb, the filaments appear as prominences.
The long filaments and other darker patches are plasma-related phenomena in the Sun’s chromosphere. They can be revealed with a H-alpha solar filter
Photos: Bill Cloutier
H-alpha Light from the Chromosphere
JBD
JBD
A prominence on the solar limb compared to the size of the Earth, captured with the Observatory’s Dancer antique telescope (JBD)
Photos: Bill Cloutier