Solar prominence. Artwork of a solar prominence extending as a huge loop from the Sun's surface. The filaments of gas here are seen linking two sunspots, dark, cooler areas on the Sun's surface. Sunspots form due to the presence of dense magnetic fields, and often form in pairs of opposite polarity. This means that charged gas can be drawn along the magnetic field lines between the two, forming arches of gas such as that seen here. These huge phenomena last a relatively short time, rarely more than a few hours. The gas in the loop is denser and cooler than its surroundings.