Solar Prominences

A solar prominence is a massive, bright feature extending outward from the Sun's surface into its outer atmosphere (the corona). 

They consist of relatively cool, dense plasma—primarily hydrogen and helium—held in place by tangled magnetic field lines.

When seen at the edge of the Sun against space, they appear as bright, glowing loops (often pinkish-red). When viewed against the bright solar disk, they look like dark, snake-like lines called filaments.