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mahatmakanejeeves

(57,434 posts)
Mon Dec 8, 2014, 10:55 AM Dec 2014

We have just had the earliest sunset of the year, on December 7.

If you live in the northern hemisphere, the sunsets will be occurring later each day from now until June. The day on which the earliest sunset occurs is not the day with the least amount of sunlight. It is also not the day on which the latest sunrise occurs.

Earliest sunset at 40 degrees N. latitude on December 7

The exact date for the earliest sunset or earliest sunrise varies by latitude. Toward the end of the first week of December, mid-temperate latitudes in the Northern Hemisphere have their earliest sunsets. The earliest sunset for 40 degrees N. latitude is on December 7. That would be the latitude of New York City (shown in Jerry Ferguson‘s photo, top of post); Philadelphia, Pennsylvania ; Kansas City, Missouri; Reno, Nevada; Beijing, China; Madrid, Spain; Naples, Italy. Meanwhile, the Southern Hemisphere’s mid-temperate latitudes are waking up to their earliest sunrises.
....

It seems paradoxical. At middle latitudes in the U.S. – and throughout the Northern Hemisphere – the earliest sunsets of the year come about two weeks before the solstice and the shortest day of the year.

Why isn't the earliest sunset on the year’s shortest day? It's because of the discrepancy between the clock and the sun. A clock ticks off exactly 24 hours from one noon to the next. But an actual day - as measured by the spin of the Earth, from what is called one “solar noon” to the next - rarely equals 24 hours exactly.

Solar noon is also called simply midday. It refers to that instant when the sun reaches its highest point for the day. In the month of December, the time period from one solar noon to the next is actually half a minute longer than 24 hours. On December 7, the sun reaches its noontime position at 11:52 a.m. local standard time. Two weeks later - on the winter solstice - the sun will reach its noontime position around 11:59 a.m. That's 7 minutes later than on December 7. ... The later clock time for solar noon also means a later clock time for sunrise and sunset.

Sunrise and Sunset, Washington, DC

You can check for any month you want.

Bonus link: Why doesn't the earliest sunset occur on the shortest day of the year?

Bonus bonus link: Equation of time
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We have just had the earliest sunset of the year, on December 7. (Original Post) mahatmakanejeeves Dec 2014 OP
Thanks for the "why" link sharp_stick Dec 2014 #1
It's like the pre-Winter Solstice... tridim Dec 2014 #2

sharp_stick

(14,400 posts)
1. Thanks for the "why" link
Mon Dec 8, 2014, 11:10 AM
Dec 2014

My kids were asking me why the earliest sunset and latest sunrise occur on different days and I've been trying to find out for them.

tridim

(45,358 posts)
2. It's like the pre-Winter Solstice...
Mon Dec 8, 2014, 02:57 PM
Dec 2014

Which IMO is the best holiday of the year, by a lot.

It should be the first day of the new year, except Jeebus.

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