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OK astronomy nerds. Let's talk about sunrise and sunset times.

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cvanc

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Here is a snip from weather.com showing the the next 10 sunrise & sunset times for me (Chicago). Why does the sunrise time hardly vary over ten days but the sunset time changes by a minute per day? That seems - well impossible, frankly.

suntimes.jpg
 

Ravenex

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It's because there are multiple factors involved. In one direction (sunrise) the factors cancel and in the other they add. I believe the answer it that the change in our position around the sun is pushing both the sunrise and sunset later but the change in inclination of the earth is lengthening the day pushing sunrise earlier and the sunset later. That would also explain why sunrise is one minute later and then earlier again. So for example if the day is getting 1 minute longer (sunrise -0.5 minutes, sunset +0.5 minutes) and the position of the earth around the sun is making the day 0.5 minutes later then you would get the results you see in the table. Sunrise would be -0.5 + 0.5 = 0 and sunset 0.5 + 0.5 = 1.
 
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Charles_McG

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Earth's rotation varies very little, but it's motion around the sun does - it's an elliptical orbit. Latest sunset leads solstice and earliest sunrise lags solstice by about 2 weeks. Rate of change varies over the year, too.

Attached is a diagram called a Hershel's Hourglass. Day of year is vertical, time of day is horizontal. Exact shape depends on latitude. You can see that the waist and hips are offset.

ImageUploadedByRocketry Forum1483023674.365115.jpg
 

dhbarr

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For a 3D version of same, see the main cam of the Long Now Project.

 
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The_Lone_Beagle

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In general, our orbit around the sun is not only elliptical, but also has other components that create deviations. See the Wikipedia article on the "analemma", here is a brief quote:

There are three parameters that affect the size and shape of the analemma — obliquity, eccentricity, and the angle between the apse line and the line of solstices. Viewed from an object with a perfectly circular orbit and no axial tilt, the Sun would always appear at the same point in the sky at the same time of day throughout the year and the analemma would be a dot. For an object with a circular orbit but significant axial tilt, the analemma would be a figure of eight with northern and southern lobes equal in size. For an object with an eccentric orbit but no axial tilt, the analemma would be a straight east–west line along the celestial equator.
https://en.wikipedia.org/wiki/Analemma
 

MClark

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It's aliens
(I tried to insert a meme of the ancient aliens guy but it did not work. If it had this post would be way funnier.)

M
 

fyrwrxz

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It's aliens
(I tried to insert a meme of the ancient aliens guy but it did not work. If it had this post would be way funnier.)

M
LMAO- It's a visual you either get or don't! Who told him that hair was stylish? A: Aliens! Somewhere in Alpha Centauri-he's a poster child for human gullibility......
 

Nathan

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It could be that you are trapped in a localized distortion of the space-time continuum. This happened once on Star Trek TNG. It that case it was caused by a creature from trans-dimensional space disguised as a Romulan.
 

The_Lone_Beagle

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Just found this video, does a good job explaining some of this in a very entertaining way:

[video=youtube;IJhgZBn-LHg]https://www.youtube.com/watch?v=IJhgZBn-LHg[/video]
 

DavidMcCann

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It's because the earth is flat and they're doing it as part of day-light savings time to screw us out of money by charging more for electricity.
 

Bat-mite

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It's because the earth is flat and they're doing it as part of day-light savings time to screw us out of money by charging more for electricity.
You beat me to it! Yes, and the all the governments of the world, even the ones at war, collude with the scientists to slow down and speed up the world's clock to make it seem like the sunrise/sunset times are changing.
 

The_Lone_Beagle

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you know, they made a video about that, too!

[video=youtube;VNqNnUJVcVs]https://www.youtube.com/watch?v=VNqNnUJVcVs[/video]
 

Nytrunner

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Exact shape depends on latitude.

View attachment 308139
Truer words never spoken.

I'm on work in the Alaskan interior temporarily.......I haven't seen the night in 2 weeks.......
Tried staying up to catch darkness one weekend, gave up ~ midnight and just went to bed.

If anybody needs me around 9pm Alaska time, I'll be out working on my tan.
 

tomsteve

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It's because the earth is flat and they're doing it as part of day-light savings time to screw us out of money by charging more for electricity.
i was told that whole daylight savings time was because there was downtime refueling the thrusters along the edge of the flat earth. the thrusters start losing power in the spring, so the rotation starts slowing down allowing more daylight. then in the summer, they( aliens) refuel the thrusters and the rotation starts speeding up and we start getting less and less daylight.
 
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