Why December Has The Longest Days

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December has the longest solar days (noon-to-noon) because of the weird way a combination of the axial tilt of the earth and the eccentricity of its elliptical orbit conspire in December. Perihelion + Solstices = Long Days.

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Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!

Thanks to Nima Doroud for contributions. Created by Henry Reich

[Poudii]

Just thinking of all the research that went into this video is stressing me out

[Tjita]

I always think I'm already going to know what these videos are about, but every single time I end up having my mind blown...

[Eric]

I always wondered why the sunrise and sunset times weren't symmetrical. Thanks for explaining it.

[velikiradojica]

-Milankovich-
-Milankovitch-
Milanković

[shpetimm]

3000 years of observations in 3 minutes :D

[vaxivop]

This is really just a fault in the English language. In Danish, we have the word "døgn" which means a full day and night or 24 hours, whereas in English only a day is used which can either mean the time where the sun is up or a full cycle of day and night aka 24 hours.

Most people say that winter has the shortest day of the year because they mean day as in the time the sun is up, whereas you are talking about a day meaning 24 hours.

In conclusion, winter has both the shortest and the longest days at the same time. Hurray for English.

[MissJubilee]

Mind blown! I’ve been wondering why the sunrise and sunset turn around at different months. I’m still not sure I grasp it, but I get the general impression of what you’re saying anyway! Thanks for that!

[Azivegu]

I dont care how long the day is, if I have to go to work in the dark and come home in the dark it will still depress the shit out of me.

[BlueBetaPro]

This video does not explain why I woke up 4 hours early today.

[bjarnes.]

I wanted to check what day was the longest, but I could only find articles about the sun solstice. Then I remembered that there was a minutephysics video about it.
Thanks, Henry!

[banescar]

I laughed tears at "REALLY not to scale". :D

[pastymccheese]

wow i never really thought about that, thats amazing :D

[Broekmanium]

December 22... my birthday... the longest day of my life... hey... I made a joke... Actually I'm just crying behind my computer right now.

[radishpineapple]

1:18 The explanation used here for describing the role of the obliquity of the ecliptic in determining the length of day is practically incomprehensible.

Here is a more intuitive explanation: 1. For observers on the Earth, the Sun appears to move eastward along a path relative to the background stars called the ecliptic; this path is due to the Earth's orbit around the Sun. 2. The Sun appears to move eastward along this path, partially counteracting the Sun's apparent westward motion due to the Earth's rotation and making the day take longer. 3. At noon during the solstices, the Sun appears to move exactly eastward along the ecliptic, maximally counteracting the westward motion and making the day take the longest. 4. At any other time of year, the Sun's motion along the ecliptic is not only eastward, but slightly diagonally up or down in the sky as well. 5. This up-down motion means that there is less eastward motion available to take away from the westward motion of the Sun. 6. During the equinoxes, the ecliptic is the most tilted at noon compared to any other time of the year, which means that there is the least amount of eastward motion available to counteract the westward motion of the Sun, making the the day the shortest.

Viewed from the Sun: during the solstices, the rotational movement of the sunlit portions of Earth is antiparallel to the orbital motion of the Earth, while at any other time of year, the motion is at an angle and counteracts the orbital movement less.

[klcousins]

LOL - Henry, love the illumination at ~1:18 - 1:24. Superb! :)

[josephhalevi]

Awesome presentation! I really enjoyed! I wish you would focus a bit more on the earth's tilt and how it affects solar noon time, and give a few more angles. You can see that it takes longer to complete its orbit when it's tilted, but I don't fully grasp it.

[DNj]

To be honest ill need a lot more time than a 3 minute video to thoroughly grab this one.

[leblife]

Always manage to blow me away MP. Well done

[stevenson]

Thank you for the video, MinutePhysics. I enjoyed it and learned a lot.

[FreakinYAY]

Around 8 hours of sunlight here in London :(