The Sun spot Active Region 1429 – incredible photo
THIS is a photograph of the Sun spot Active Region 1429 as seen by Alan Friedman.
Alan uses an Hα filter, which cuts out almost all the light from the Sun except for a narrow slice of color emitted by warm hydrogen. This reduces the glare hugely, and reveals delicate structures in the Sun’s plasma. He then inverts the image, so bright things appear dark, and vice-versa. That’s an old astronomer’s trick that makes fainter things easier to see. He also used a false color palette to make it appear reddish. That’s actually a good idea, since the color of light emitted by the hydrogen is at 6563 Angstroms, right in the middle of the red part of the spectrum!