A solstice is either of two points on the ecliptic, midway between the equinoxes, at which the Sun reaches its greatest northern declination (summer solstice in the northern hemisphere, winter solstice in the southern, on 21 June) and greatest southern declination (vice versa, on 22 December). At these points occur the longest day and shortest night in one hemisphere of Earth, and vice versa in the other. The solstitial points are the Sun's positions when it is momentarily stationary on these occasions. The solstitial colure is the hour angle that passes through the solstices on the celestial sphere.