June 21 is said to be the longest day of the year, yet in the News and Observer, sunrise and sunset for June 21 and June 22 are listed as the same time. What am I missing?
Posted June 24, 2007
MIKE MOSS SAYS: Glenn, The main thing missing is added precision in the calculated sunrise and sunset times, so that they would list seconds as well as minutes for the times. For a week or two around the time of the summer solstice, the apparent position of the sun at its highest point in our sky each day changes very little, compared to the rates of change near the equinoxes, for example. In fact, the name solstice derives from that fact (sol is latin for "sun," while sistere means "to stand still"). For that reason, the times of sunrise and sunset change very slowly, so that on many days in mid to late June the times, when rounded off to the nearest minute, appear to remain the same for several days in a row. Nonetheless, with the Summer solstice occuring at 2:06 pm EDT on 21 June, you can be pretty certain that a very detailed calculation would show that day to have the longest interval between sunrise and sunset, even if its only by a few seconds. You can easily see the roundoff effect by calculating a yearly table of sunrise and sunset times at the US Naval Observatory web site. Here is the address, if you're interested -