- the solstice on or about December 21st that marks the beginning of winter in the Northern Hemisphere.
- the time at which the sun is at its southernmost point in the sky (northernmost point in the S hemisphere) appearing at noon at its lowest altitude above the horizon. It occurs about December 22 (June 21 in the S hemisphere)
- the point on the celestial sphere, opposite the summer solstice, at which the ecliptic is furthest south from the celestial equator. Right ascension: 18 hours; declination: –23.5°
