Q&A: Summer Solstice

Question: I heard on the weather report that the Summer Solstice happens this month. Will I see anything special in the sky? What exactly happens? — RS, Phoenix, AZ

Answer: Something special will indeed happen. At precisely 11:46 pm MDT (Arizona time), on June 19th, the Sun will reach its northernmost point in the sky.

No doubt you’ve noticed how the Sun rises and sets in different places at different times of the year. If you haven’t, you really need to spend more time outside. On the day of the Summer Solstice the Sun will rise and set at its farthest north points of the year. Between those two points, it will travel along its highest arc through the sky. The consequences of this motion are threefold.

First, this will be the day of the year with the greatest amount of daylight and the least amount of night. In Arizona, the numbers work out to 14¼  hours of daylight and 9¾  hours of night.

Second, this will be the day of the earliest sunrise (5:23 am) and the latest sunset (7:38 pm). Actually, this is not exactly true due to some complications with latitude and longitude, but it’s close enough.

Third, it will be hot outside. The reason for the season is the path of the Sun. Its high arc through the sky, and the longer period of daylight, allow the Sun to heat the Earth (at least in the northern hemisphere) more so than on any other day. Stay cool.

Q&A: The Moon Illusion
Two Inferior Planets Visible