Main sequence stars show an extremely wide range of luminosities. The most luminous (and most massive) are more than a million times brighter than the Sun. If the Sun were replaced by one of these stars, the temperature of the Earth would rise to about 10,000 K, so the Earth and the other terrestrial planets would be quickly vaporized. The smallest, least massive main sequence stars are about 1000 times dimmer than the Sun. If one of these stars replaced the Sun, the Earth’s temperature would fall to about 50 K, approximately the temperature of Pluto. The spectral types, temperatures, radii, and luminosities for main sequence stars of various masses are given in Table 19-1. In Table 19-1, masses, radii, and luminosities are given in terms of those of the Sun (M☉, R☉, and L☉).