The () is the Star at the center of the Solar System . The Earth and other matter (including other Planet s, Asteroid s, Meteoroid s, Comet s and Dust ) Orbit the Sun, which by itself accounts for about 99.8% of the Solar System 's Mass . Energy from the Sun—in the form of sunlight—supports almost all life on Earth via Photosynthesis , and drives the Earth's Climate and weather.
The Sun is composed of Hydrogen (about 74% of its mass, or 92% of its volume), Helium (about 25% of mass, 7% of volume), and trace quantities of other elements. The Sun has a Spectral Class of G2V. ''G2'' implies that it has a surface temperature of approximately 5,780 K (or approximately 5,515 degrees Celsius / 9,940 Fahrenheit), giving it a White color which, because of atmospheric Scattering , appears yellow as seen from the surface of the Earth. This is a subtractive effect, as the Preferential Scattering of blue photons (causing the sky color) removes enough blue light to leave a residual reddishness that is perceived as yellow. (When low enough in the sky, the Sun appears orange or red, due to this scattering.)
Its spectrum contains Line s of ionized and neutral metals as well as very weak hydrogen lines. The ''V'' ( Roman Five ) suffix indicates that the Sun, like most stars, is a Main Sequence star. This means that it generates its energy by Nuclear Fusion of Hydrogen nuclei into Helium and is in a state of Hydrostatic Equilibrium , neither contracting nor expanding over time. There are more than 100 million G2 class stars in our galaxy. Because of logarithmic size distribution, the Sun is actually brighter than 85% of the stars in the Galaxy , most of which are Red Dwarf s.1
|
