latitudes approximately 23°27′ N and 23°27′ S of the terrestrial Equator, respectively. These latitudes correspond to the northernmost and southernmost declinations of the Sun's (ecliptic) ecliptic (q.v.) to the celestial equator. At the summer solstice (in the Northern Hemisphere), around June 21, the Sun attains its greatest declination north and is directly over the Tropic of Cancer. At that time the Sun appears in the constellation Gemini, but much earlier in history, it lay in the constellation Cancer, thereby resulting in the designation Tropic of Cancer. Similarly, at the winter solstice (Northern Hemisphere), around December 21, the Sun is directly over the Tropic of Capricorn and lies within the boundaries of the constellation Sagittarius, having reached its southernmost declination in the ecliptic. Previously, however, it appeared in the constellation Capricorn at the winter solstice, and so the name Tropic of Capricorn. Because of the gradual change in the direction of the Earth's axis of rotation, the Sun will reappear in the constellations of Cancer and Capricorn in approximately 24,000 years.