What is outline of the sun?

The outline of the Sun is a circular shape, with an average diameter of 1.39 million kilometers (864,938 miles). It is composed mainly of hydrogen and helium gas, which are constantly undergoing fusion reactions in its core, producing energy and light. The outer layer of the Sun, known as the photosphere, appears as a bright, yellow disk when viewed from Earth. The Sun also has a number of features on its surface, including sunspots, faculae, and prominences, which can be observed with special solar telescopes. The outline of the Sun is also surrounded by an atmosphere or corona, which is visible during a total solar eclipse and is much hotter than the surface of the Sun itself.