Alan used a filter that lets through only a very narrow wavelength of light emitted by hydrogen (called Hα for those of you keeping track at home), so this tracks the activity of gas on the solar surface. He also inverts the image of the solar disk (makes it a negative) to increase contrast.
The smoke to the left of the sun is actually leftover material from an erupting sunspot. Seeing the sun so close and personal makes it easy for us to forget how big it is, Earth is literally a mere dot compared to this beast. [Alan Friedman via Discover]