By Calvin L. Chrisman
Many folks in town would tell you, based on the recent hot weather that summer has been here for a while. Others would say that it began after Memorial Day; while students might say it began when school got out. Officially, it does not begin until 1:16 p.m. EDT on Tuesday, June 21st when the Sun arrives at its highest northern elevation during the year. This is the summer solstice and is the commonly referred to as longest day of the year since it has the longest period of daylight.
The seasons we experience are caused by this regular north to south movement of the Sun. The Earth is not straight up and down relative to its orbit around the Sun. Instead, it is tilted at about eighteen and one-half degrees. During the summer, the northern hemisphere is pointed most directly at the Sun, resulting in more daylight. During the winter, the northern hemisphere is pointed more away from the Sun causing less daylight. The opposite is true for the southern hemisphere.
The path of the Sun over the face of the Earth on this day defines two familiar lines on our globe. On this day, the Sun is directly overhead for anyone located on the Tropic of Cancer. For those of us farther north, the Sun is at its highest, but it is not directly overhead. The other line defined by the Sun’s path on this day is the Antarctic Circle. Anyone at the Antarctic Circle on this day will experience 24 hours of total darkness. Those farther south will, of course, experience longer periods of darkness before the Sun returns. The Tropic of Capricorn and the Arctic Circle are drawn by the Sun’s path during our winter solstice.
Although it is technically a point in time, the full day on which the solstice occurs is sometimes referred to as the summer solstice or Midsummer’s in some cultures. In these places, particularly northern Europe, Midsummer’s Eve is a major holiday involving bonfires and other celebrations. In ancient times, certain mid-summer plants were believed to have miraculous healing powers and they were picked at night. The bonfires were lit to ward off evil spirits that were believed to roam freely as the Sun began its journey south.
Last month, there were four planets to see in the dawn sky. During June, Mercury will reach what is called superior conjunction. This is a fancy term meaning that it is almost directly behind the Sun from our vantage point and therefore impossible to observe. However, there remain three beautiful planets to be seen by early risers. Jupiter is up well before sunup. In morning twilight, you will be able to see much fainter Mars to Jupiter’s lower left. Very bright Venus completes the trio.