Thus, the nearer G-type stars have been considered as prime candidates for possible beacon signals. The first star at which Frank Drake pointed an antenna in his famous Project Ozma, is a G-type star, Tau Ceti. Stars of the spectral types F and K are close enough to G to also be considered as likely candidates. The second star at which Drake pointed his antenna is a K-type star, Epsilon Eridani. The temperature of a star is related to its color.
Blue stars are hotter than yellow stars and yellow stars are hotter than red ones.
A star follows a life-cycle during which it may at different times be an Infrared star, a yellow dwarf, a red giant and a white dwarf. The elements in a star can be determined from lines they produce in the star's spectrum. The sun is a G-type star. SETI searches are commonly directed at F, G and K stars because they are somewhat similar to the sun. In this range of wavelengths natural noise is least.