Solar Filament in H-alpha Light

Credit: Big Bear Solar Observatory

This photo of the Sun includes several solar filaments, which look like dark lines or curves. Filaments are huge arcs of plasma suspended in the Sun's atmosphere by magnetic fields. They appear dark in this image because they are cooler than the Sun's surface behind them. This picture was taken on July 18, 2000 using a filter that only transmits a specific wavelength of red light called the H-alpha band.