Question

Hundreds, even thousands of stars may be easily observed in the night sky. What process produces the light from the stars?

A.
gravitational waves, released by the high mass of stars
B.
chemical combustion of hydrogen
C.
nuclear fusion, in which atomic nuclei combine
D.
radioactive decay of heavy elements

Answer 1

C. nuclear fusion, in which atomic nuclei combine.

Stars shine mainly by fusing hydrogen into helium in their cores. The fusion releases enormous energy (mass converted to energy via E = mc^2) as photons and particles; that energy travels outward and is emitted as the starlight we see. Chemical combustion and radioactive decay are negligible compared with fusion, and gravitational waves are not a primary light source.