The Sun

The Sun is an average yellow dwarf star. The Sun mostly contains the elements hydrogen and helium. The light we see from the Sun originates from a layer called the photosphere. The photosphere has a temperature of 5780 K. The core of the Sun is at 15,000,000 K. In the core, nuclear fusion converts hydrogen into helium. The energy released transfers from the core to the photosphere through radiation and convective layers. Dark sunspots are observed scattered across the photosphere. Sunspots are caused by strong, local magnetic fields. The number of sunspots visible at any given time waxes and wanes in a cycle with a period of 22 years. Violent eruptions in the photosphere appear as prominences and flares. Above the photosphere is a relatively thin layer called the chromosphere. The chromosphere is the lower atmosphere of the Sun. The upper atmosphere of the Sun is called the corona. The solar wind consists of highly energetic ions escaping the Sun’s gravity from the corona.