What caused the Sun to start emitting light?

The Sun produces light by a nuclear reaction called fusion. As atoms of hydrogen combine to form helium, they produce vast amounts of heat and light. ... The central core of the sun, where heat and light are produced, has a temperature of 15 million degrees.

Explanation:

totally from my noggin

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.