STONEHENGE
Every year, thousands of visitors gather at the neolithic Stonehenge monument in Wiltshire, England, to celebrate the first sunrise of the Northern Hemisphere summer. Stonehenge was built in three phases between about 3,000 B.C. and 1,600 B.C., and its purpose remains under study. However, it’s known that if you stand in just the right place inside the Stonehenge monument on the day of the northern summer solstice, facing northeast through the entrance towards a rough-hewn stone outside the circle – known as the Heel Stone – you will see the sun rise above the Heel Stone, as illustrated in the image at the top. In the Northern Hemisphere at this time of year, the sun is shining on us most directly at midday. Except at high northerly latitudes, above the Arctic Circle – where daylight is continuous for many months – the day on which the summer solstice occurs is the day of the year with the longest period of daylight. Meanwhile, it is the shortest day for Earth’s Southern H...