The June Solstice occurs at 17:16 UTC on 21 June 2011. On this date, the Sun reaches the northernmost line of latitude (the Tropic of Cancer, 23.5°N) where the midday Sun is at the zenith (the imaginary point directly overhead). At northern mid-latitude locations, the midday Sun reaches its maximum altitude (annually) and the duration of insolation (number of hours of daylight) is greatest. For example, in Washington, D.C. the midday Sun will reach an altitude of 74.5 degrees above the horizon and there will be nearly 15 hours of daylight (14h54m). Also, the Sun rises farthest to the north of east (to the far left of the Washington Monument in the accompanying photograph) and sets farthest to the north of west than at any other time of year.
It’s interesting to note that the apparent paths of the Sun and Moon across the sky are exactly opposite at the solstices: near the time of the June Solstice, the Full Moon follows the path of the Sun during the December Solstice; near the time of the December Solstice, the Full Moon follows the path of the Sun during the June Solstice. For more information, see Yin and Yang – Dynamic Equilibrium in the Universe.
Posted from Arlington, Virginia, United States.