If you open your copy of the 2015 Farmers’ Almanac to page 128, you’ll see that the earliest sunrise this year is listed for June 14th, at 5:30 a.m. at 40° North Latitude and 75° West Longitude.
Actually, the Sun is listed as rising at 5:30 a.m. every day from June 11th through the 17th, but it will actually rise a few seconds earlier on the 14th than it does on the 13th or the 15th.
While everyone knows that the days are longer in the summer, many people are surprised to learn that the earliest sunrise of the year doesn’t occur on the longest day of the year (in terms of daylight) — the Summer Solstice, which falls on June 21st this year — but comes nearly a week before it. But why?
The discrepancy is caused by the Earth’s elliptical orbit around the Sun. The Earth moves faster in its orbit during January (when we’re closest to the Sun) than in July, when we’re farthest away. Because of this motion, the Sun’s path through the sky, when charted on a day-by-day basis, appears to take a lopsided figure-8 pattern astronomers call an “analemma.”
Because of this, the conventional wisdom that the Sun lies directly overhead at noon, splitting the day into two equal parts, is actually not true. The Sun can line up with the meridian as much as 15 minutes before or after noon. Anyone with a garden sundial is probably already aware of this discrepancy, known as “The Equation of Time.”
The Sun’s looping path also explains why the earliest sunrise of the year, and the latest sunset, do not exactly coincide with the Summer Solstice. Instead, the earliest sunrise occurs about a week before the Solstice, while the latest sunset occurs about a week after it, even though the exact date depends on your latitude. At northern latitudes (at Seattle) the latest sunset happens a few days before June 27. Southern latitudes (at Mexico City), the latest sunset won’t happen until early July.
A similar effect happens during the Winter Solstice, when the earliest sunset arrives about two weeks before the December solstice, and the latest sunrise occurs about two weeks afterward.
So, on June 14th, when you’re heading outside to hang your flag for Flag Day, be sure to greet the earliest sunrise of the year!