The word from mythology for today is
saturnine, which comes from the name of the Roman god Saturn. The word comes from the belief that someone born under the influence of the planet Saturn was gloomy and morose. In medieval astrology, of the known planets Saturn was most distant from the sun, and therefore the most cold and slow. To learn more about the Roman god Saturn, see
Wikipedia.
Relate words:
jovial and
mercurial.
This is a depiction of
Saturn by Poildoro da Caravaggio.