These charged particles glow from their high temperatures, and because more of them have become concentrated right around the magnetic field line, they outline it with their light. This glowing arch is called a prominence . It should be no surprise that sunspot pairs and prominences are often closely associated. If you look down on the surface of the sun at a prominence, you will see it as a dark line called a filament projected onto the surface. Prominences as arches are best seen in profile along the edge of the sun.
Prominences are sometimes transitory, lasting only a few minutes or hours.
More typically, though, they endure for days, even up to a month. Flares Flares are extremely energetic and brief outbursts on the sun's surface, occurring within all three layers of its atmosphere. In only a few seconds to a few minutes, they rise to temperatures of many millions of degrees Kelvin, where they give off intense energy in x-rays and UV light. Once those flare particles have made the 2-3 day trip to reach the earth, they interact with the earth's upper atmosphere at the two poles to produce the aurorae borealis and australis . Flares almost always occur at or near the peak of the 11-year cycle of solar activity.