Phil Plait, aka The Bad Astronomer, had this to say:

This picture was taken by Alan Friedman…

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. Somehow this adds a three-dimensional quality to the picture, and reveals an amazing amount of texture. I swear I had a rug in my bedroom growing up that was this texture (though somewhat cooler and less burny).

The scene-stealer is that detached prominence off to the left. That’s the leftover material ejected from the Sun by an erupting sunspot (you can see other sunspots in the picture as well). The gas is ionized — a plasma — and so it’s affected by magnetic fields. The material follows the magnetic field of the Sun in the explosion, lifting it off the surface and into space. Sometimes it falls back, and sometimes it leaves the Sun entirely. In this case, Alan caught some of the material at what looks like the top of its trajectory.

Here’s another bit of science that will blow your mind. The mass of the prominence in this picture “can easily top 10 billion tons“!

via nerdist, bad astronomer, alan friedman