Happy earliest sunset of the year: December 7

[mahatmakanejeeves]

Yeah, I know it's been done. I'm doing it again.

See our story on the winter solstice from last year: https://wapo.st/2JWoZFg via
@justingrieser


Here's the relevant snippet:

Hey
@capitalweather
Can you please remind us #LaymansTermsGang folks why the earliest sunset of the year is over the next few days and NOT on Winter Solstice 12/21? Thanks!
@PoPville

Link to tweet

Fri Dec 7, 2018: Happy earliest sunset of the year: December 7

* In the northern hemisphere.
** Give or take.

2018 update: I'm checking for New York City. The sunset has stalled at 4:28 p.m. for every day from December 3 until December 12.

December 2018 — Sun in New York

It is worth looking at a thread from a few days ago, in which there was a discussion of the differences in sunsets according to latitudes:

I'm watching Pres Bush's casket arrive at capitol.

It's almost pitch dark here in Boston, and the sky above the capitol is light. How can that be?

tia
las

******

Previously at DU:

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

Things vary, depending on where you live.

The earliest sunset in Washington, DC, occurs on or around December 7 or 8 in 2015. DC's sunset is stalled at 4:46 for over a week. New York City has the same sunset time, 4:28 p.m., for three days.

http://www.timeanddate.com/sun/usa/new-york?month=12

http://www.timeanddate.com/sun/usa/washington-dc

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.

But, but.... What's the reason?

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

[Blues Heron]

1. I think the reason it's not on the actual solstice

is because we standardized the day to 24 hours as opposed to being the time from one noon to the next which actually shifts as we slow down in our orbit.

If we did local solar time (resetting the clock as needed to sync with solar noon each day) I believe the earliest sunset, latest sunrise and shortest day would all be on the solstice. I could be wrong though.


on edit - I shoulda read the whole thing - the info is there.

[samnsara]

2. In live in a deep canyon and yesterday it is dusk at 2 30 pm.....great, going to start getting dark

...at 1 ish...

[elleng]

3. Thanks. I really like the CWG guys.

Last edited Mon Dec 7, 2020, 06:05 PM - Edit history (1)

Waiting to catch today's sunset, 'scheduled' for 4:46.

'Shows' here a bit earlier.

[mahatmakanejeeves]

4. Please allow me to consult my 1998 Bob Ryan's Almanac.

The last time the sun set at 4:47 was December 1, which was the 335th day of the year in a non-leap year, like 1998

On December 2, 1998, the sun set at 4:46. It set at 4:46 through December 11. Finally, on December 12, it set at 4:47 again.

1998 wasn't a leap year. To adjust, we shift things up a day. Thus the last time the sun set at 4:47 in 2020 was November 30, which was the 335th day of the year in a leap year. So I guess our next 4:47 sunset this year will be on December 11.

I think I did that right. At any rate, depending on whether it's a leap year, you have ten days centered around the 6th or the 7th where the sun sets at 4:46 in DC.

I miss Bob Ryan. I bought his almanac every year. 99 cents at the Giant, and all proceeds went to a lot of good things.



Source: http://capitalclimate.blogspot.com/2010/02/bob-ryan-leaving-wrc-channel-4.html

It's cleared up, so you should have a good view of the space station tonight.

For Pax River:

https://spotthestation.nasa.gov/sightings/view.cfm?country=United_States®ion=Maryland&city=Patuxent_River_NAS#.X86Osmg3k2w

Oh, yeah. 5:46 tonight, and 5:48 on Wednesday.

[elleng]

5. HERE in southern MD, @ 4:39 p.m. Patuxent River