Ephemeris: 05/21/2024 – Looking ahead to the summer solstice

This is Ephemeris for Tuesday, May 21st. Today the Sun will be up for 15 hours and 3 minutes, setting at 9:11, and it will rise tomorrow at 6:07. The Moon, 2 days before full, will set at 5:14 tomorrow morning.

Summer is coming. Days are definitely warmer. The Sun’s out longer. Yesterday we passed the 15 hours of daytime. Summer will start a month from yesterday on the 20th of June. We normally expect the solstices on the 21st of June and 21st of December and the equinoxes on the 21st of March and the 23rd of September. However, we haven’t had, in our time zone at least, spring start on the 21st of March since 1987. The slow wondering of the equinox and solstice dates are due to the fact that the seasonal year, also called the tropical year, is not exactly 365 and a quarter days long. It is slightly shorter than that, which is the reason in 1582 Pope Gregory the 13th decreed that the calendar would be reformed which is the Gregorian Calendar we have now.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

Addendum

I talk about the calendar in much more detail in this post: https://bobmoler.wordpress.com/2016/02/28/02282016-ephemeris-extra-the-years-of-our-lives/