The Sun

The Sun is Earth's parent star, the center of the Solar System.The Sun is classified as a G2 star, meaning that it has a surface temperature of about 5800 degrees Kelvin.The Sun is estimated to be about 4.57 billion years old, that is, it has officially been a star, or fusion reactor, for this time period. The Sun is middle aged: it is expected to last another 4.5 to 5.5 billion years as a regular, or main sequence star.The Sun is huge: its diameter is 109 times that of Earth, and its mass is about 333,000 times that of Earth.The Sun has a rotational period of just over 25 days.The Sun is a mere 93 million miles from Earth, on average, but it, and by extension the Solar System, is about 25,000 light years from the center of our galaxy, the Milky Way. It takes the Sun and the Solar System about 225 to 250 million years to orbit the Milky Way's center.During a solar eclipse, it's possible to see the colored lower atmosphere of the Sun (called the chromosphere), and the thin, ethereally fine, magnetically animated upper atmosphere (called the corona). Temperatures in the corona run into the millions of degrees Kelvin. The Sun exhibits strong magnetic fields. Areas of intense magnetic field strength exhibit so-called sunspots, or relatively dark spots on the surface atmosphere, or photosphere, of the Sun.The Sun is the main source of energy and light on Earth. It's current intensity, the solar constant, is on average 1366 watts per square meter.The Sun is not big enough to explode when it dies. Instead, it will become a white dwarf. Nevertheless, during its "death throes", its volume will increase enormously, becoming a red giant, such that its outer atmosphere will then entirely encapsulate the Earth and its orbit.