The Sun: its size, composition, motion, and layers

The Sun is a fairly ordinary star about 4.6 billion years old. It is about 109 times Earth's diameter (roughly 1.4 million km across) and holds about 333,000 times Earth's mass, more than 99 percent of the solar system's mass. By mass it is about 73 percent hydrogen and 25 percent helium, with small amounts of heavier elements. Its layers are the core, where nuclear fusion turns hydrogen into helium at about 15 million kelvins; the radiative zone, where energy slowly works outward as radiation; the convection zone, where hot gas rises and cooler gas sinks; the photosphere, the visible surface at about 5,800 kelvins; and the outer atmosphere, the chromosphere and the corona, which is surprisingly over a million kelvins. The Sun rotates faster at its equator (about 25 days) than near its poles (about 35 days), and it carries the whole solar system around the center of the Milky Way roughly once every 230 million years.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report