For this week’s Starwatch, we will talk facts about the sun around the time of the summer solstice.
Although the longest day of the year falls on the summer solstice (14 hours, 38 minutes, and 22 seconds of sunlight), the earliest sunrises occur before the first day of summer and the latest sunsets occur afterward.
This is due to a few things. One reason is the days aren’t exactly 24 hours long. The day length is measured from solar noon to solar noon. Around this time of year, the days are longer by about 1/4 of a minute. Other factors include Earth’s tilt and elliptical orbit.
The earliest sunrises in the Tri-Cities are at 6:11 a.m. This happens now through June 19th.
The latest sunsets in the Tri-Cities are 8:51 p.m. This occurs from June 24th to July 2nd.
The longest sunsets also occur during solstices. This is because the sun sets north of due west in the summer. Since the angle the sun approaches the horizon is shallower, it takes more time for the sun to sink completely below the horizon.