SUN, THE

   is a star; is the centre of the solar system, as it is in consequence called, is a globe consisting of a mass of vapour at white heat, and of such enormous size that it is 500 times larger than all the planets of the system put together, or of a bulk one million and a half times greater than the earth, from which it is ninety-two and a half million miles distant; the bright surface of it is called the photosphere, and this brightness is diversified with brighter spots called faculæ, and dark ones called sun-spots, and by watching which latter as they move over the sun's disk we find it takes 25 days to revolve on its axis, and by means of SPECTRUM ANALYSIS (q.v.) find it is composed of hydrogen and a number of vaporised metals.