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16 Jan 2016

Thanks to a strange orbit and weird time zones, can be of summer isn’t always a similar

Q: Next year, my husband and I will celebrate our 58th wedding. For 57 years, we also have celebrated our anniversary on June 21, day one of summer plus the longest day of 12 months. I have kept calendars the past 25 years or even more, and also on all of these calendars, June 21 is listed as day one of summer. So why do most of my new 2016 calendars list day one of summer as June 20? Whose bright idea maybe it was to change this date in the end these years? The first day of spring, fall and winter are the same.

Clifford and Judy Gruner, of Highland

A: Dare I risk ruining a half-century of marital contentment by suggesting you two lovebirds happen to be laboring under the misunderstanding that June 21 always heralds the start of summer?

Well, hoping you agree that ignorance is seldom bliss, i want to put it to you personally straight: Because of our very poor calendar, summer will start not only on June 21 but June 20 and in some cases June 22. During your own marriage, summer in St. Louis arrived on June 20 seven times. But due to the system of their time zones we use on planet earth, you merely didn’t comprehend it. Let me try and explain:

The biggest problem may be which you think the planet earth makes a complete orbit throughout the sun every 365 days. So, you figure, should the planet reaches a certain part of that orbit today, it will likely be at that same point at precisely the same time on Dec. 26, 2016. Therefore, the summertime solstice really should be at the exact time annually. What could be simpler than that?

In reality, it’s not too simple in any way. It actually takes the Earth about 365 1/4 days to orbit the sun's rays — or, as “Star Trek’s” Mr. Spock would let you know, 365 days, 5 hours, 49 minutes and 48 seconds to get exact. So it requires nearly one more six hours to arrive at the identical point in our orbit from year to year. As a result, the summertime solstice gets pushed back about six hours yearly, too.

Of course, Pope Gregory XIII experimented with correct with this with his new calendar in 1582 with the help of one extra leap day just about every four years. By doing this, we at the least keep the timing of the summer months solstice inside of a reasonably narrow timeframe rather than watching it drift to your date earlier and earlier in June the way it had within the old calendar designed by Roman emperor Julius Caesar. Still, even our calendar is poor at taking our odd orbital time under consideration. Therefore, for this reason constant fudging for making the calendar believe Mother Nature, the start of summer still can fall in just a three-day window.

Solstice, furthermore, combines the Latin words “sol” for “sun” and “sistere,” which implies “to come to some stop or stand still.” At the time of summer months solstice, sunshine reaches its northernmost position as seen through the Earth. At that moment, no move north or south mainly because it would on just about every other day of the entire year but stands still before it actually starts to decline to florida again. The opposite occurs in the winter solstice.

As you note, this usually happens on June 21. In 2013, St. Louisans greeted the arrival of summer at only past midnight — 12:05 a.m. In 2014, it absolutely was 5:52 a.m. — or nearly six hours later, as I talked about earlier. This year, it turned out later again by about six hours —11:39 a.m.

Following this pattern, you’d expect the winter solstice 2016 time in 2016 that occur about 6 p.m. on June 21. But guess what happens? It’s a leap year, so they’re throwing an additional 24 hours into the season. In return, the solstice gets shoved back a whole day — in order to 5:35 p.m. on June 20. Even in 2017, summer will become here at 11:25 p.m. on June 20 before moving time for June 21 for 2018 and 2019.


The solstice occurring on June 20 is not as rare within your marriage as you have visit believe. Since 1988, it offers occurred on June 20 during every leap year — seven times to all.

So why have every one of your calendars told you that it was June 21? Simple — it’s as a result of difference with time zones. Remember that summer months solstice occurs for the exact same moment for everybody on Earth whether it’s midday where these are or the dead of night. But the calendar you hold on the wall can’t take every local time zone into mind, therefore it uses UTC (the coordinated universal time), that's similar to Greenwich (England) Mean Time, since it's standard.

As it happens, UTC is five hours prior to Central Daylight Time in St. Louis, so if your summer solstice occurs here anytime after about 7 p.m. on June 20, it’s already June 21 from the UTC region — and that’s the morning you’ll find in your calendar. But I’ll bet when you check your 2012 calendar, you’ll learn that summer going on June 20 because which was the first time since 1896 how the solstice occurred on June 20 inside UTC zone. Starting buy, you may expect it to occur much more regularly — 12 times within the next 34 years, the truth is. Conversely, there hasn’t been a summer solstice UTC on June 22 since 1975 nor could there be another until 2203. St. Louis hasn’t seen one since 1951.

Not surprisingly, the spring and fall equinoxes as well because the the december solstice 2015 have similar two- and three-day windows.

Today’s trivia

True or false: The Earth is really at its most distant point from direct sunlight during our torrid summers.

Answer to Friday’s trivia: In 1974, Canadian postal workers seen that letters addressed to Santa were being classified as undeliverable, so, as opposed to disappoint the young writers, the staff began answering the letters themselves. Volume soon increased exponentially, prompting Canada Post to create an official Santa Claus letter-response put in 1983. Now, students are encouraged to write Santa in care on the North Pole, Canada. St. Nick has even been given his personal personal postal code — H0H 0H0, certainly. For more details on first day of spring please visit my website.



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