This series presents views of the Sun from NASA’s Solar Dynamics Observatory (SDO). The SDO spacecraft was launched February 11, 2010, and began collecting data a few months later.
Active Sun is a term applied to the Sun around the maximum of the sunspot cycle, when the profusion of active regions ensures a high level of solar activity.
The typical sunspot has structure and regularity that give us clues as to the nature of the spots. Spots are darker and thus cooler than the surrounding photosphere. A well-developed spot will have a central dark umbra and a lighter, striated penumbra. Within the region of the spot we see no granulation, Because granulation supplies the surface with fresh, hot gas. Stop the granulation and the surface should cool. Spots also like to occur in pairs.
The Sun has an 11-year sunspot cycle. Maunder found regularity in the location of the spots during the sunspot cycle. At the beginning of a cycle, the spots (few in number) are appearing at a higher latitude (about 30° from the Sun's equator). As the cycle progresses, the spots form closer and closer to the equator. Sunspot maximum is reached as the spots are forming at about 15° from the equator. The numbers of spots then decrease, but continue forming closer to the Sun's equator. By the end of the cycle, the spots are forming very close to the equator as spots from the new cycle are beginning to appear at higher latitude.