# Speed of Rising/Setting Sun **URL:** \ **Category:** Factual Questions\ **Created:** [June 3, 2002, 3:06am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069 "2002-06-03T03:06:16Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Helen\_s\_Eidolon](https://avatars.discourse-cdn.com/v4/letter/h/8edcca/32.png) [@Helen\_s\_Eidolon](https://boards.straightdope.com/u/Helen_s_Eidolon)\ **Post date:** [June 3, 2002, 3:06am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/1 "2002-06-03T03:06:16Z")
My father would like to know, which happens faster (if either), the rising or the setting of the sun. Does it depend on seasons, latitude etc.? ---
**Author:** ![Duck\_Duck\_Goose](https://avatars.discourse-cdn.com/v4/letter/d/50afbb/32.png) [@Duck\_Duck\_Goose](https://boards.straightdope.com/u/Duck_Duck_Goose)\ **Post date:** [June 3, 2002, 3:09am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/2 "2002-06-03T03:09:28Z")
Um, maybe I’m missing something, but doesn’t the Earth rotate at the same constant speed, 24/7/365? So how could the sun “rise” or “set” faster or slower at one time of day or season of the year? What? 😕 ---
**Author:** ![Duck\_Duck\_Goose](https://avatars.discourse-cdn.com/v4/letter/d/50afbb/32.png) [@Duck\_Duck\_Goose](https://boards.straightdope.com/u/Duck_Duck_Goose)\ **Post date:** [June 3, 2002, 3:14am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/3 "2002-06-03T03:14:11Z")
[I have this mental image of the Earth’s rotation suddenly speeding up every time the Greater Montreal area approaches the terminator–“okay, let 'er rip, boys!” And the Earth twirls just a bit faster for those few minutes… Like playing with the VCR’s Fast Forward button] 😃 ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [June 3, 2002, 3:47am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/4 "2002-06-03T03:47:11Z")
Well, it does depend on seasons, due to the angle that the sun is making as it descends. It goes slower in winter (in the northern hemisphere), because with the shallower angle, it has to travel farther to get completely down. ---
**Author:** ![Helen\_s\_Eidolon](https://avatars.discourse-cdn.com/v4/letter/h/8edcca/32.png) [@Helen\_s\_Eidolon](https://boards.straightdope.com/u/Helen_s_Eidolon)\ **Post date:** [June 3, 2002, 3:49am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/5 "2002-06-03T03:49:15Z")
That’s pretty much what I thought, **DDG** , but my father is convinced that since both the sun and the earth are in motion, and are in different positions relative to each other at any given moment, the positions would affect the speed of the sunrise/set. (Haha at the mental image!) ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [June 3, 2002, 4:04am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/6 "2002-06-03T04:04:31Z")
This reminds of a car commercial I’ve seen. A driver, gender unclear, is parked on a highway with easy listenin’ music playin as the sun sets. Driver suddenly pulls car into gear and races the car west at high speeds, making the sun apparantly rise. Driver then parks and watches another suset, music still playing. Assuming the driver likes watching a sunrise for five minutes, then races west for ten minutes at a respectable 200kph, how far North (or South) would the person have to be to watch another five-minute sunset? ---
**Author:** ![Earthling](https://avatars.discourse-cdn.com/v4/letter/e/90db22/32.png) [@Earthling](https://boards.straightdope.com/u/Earthling)\ **Post date:** [June 3, 2002, 4:08am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/7 "2002-06-03T04:08:22Z")
[Atmospheric refraction](http://www.srrb.noaa.gov/highlights/sunrise/glossary.html#atmosphericrefraction) causes celestial objects near the horizon to appear higher in the sky than they really are. That being the case, the sun should appear to “rush” as it rises and “linger” as it sets (if I understand the [apparent sunrise & sunset](http://www.srrb.noaa.gov/highlights/sunrise/glossary.html#apparentsunrise) phenomenon correctly, that is). ---
**Author:** ![The\_Stafford\_Cripps](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_stafford_cripps/32/7167_2.png) [@The\_Stafford\_Cripps](https://boards.straightdope.com/u/The_Stafford_Cripps)\ **Post date:** [June 3, 2002, 9:34am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/8 "2002-06-03T09:34:04Z")
> [@](#): > > \*Originally posted by CurtC \* > \*\*Well, it does depend on seasons, due to the angle that the sun is making as it descends. It goes slower in winter (in the northern hemisphere), because with the shallower angle, it has to travel farther to get completely down. \*\* Also on any given day the further from the equator you are the shallower the angle is of the sun’s descent / ascent. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [June 3, 2002, 9:47am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/9 "2002-06-03T09:47:33Z")
If you happen to be sitting at one of the poles, the sun takes a couple days, I think, to go from first touching the horizon to last touching in the fall and the opposite in the spring. At the equator, at the solstice, it takes 2 minutes, slightly more at the equinoxes. In between, it takes different amounts of time. It all depends on the angle between the sun’s path and the horizon and this varies with the latitude and season. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [June 3, 2002, 1:34pm UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/10 "2002-06-03T13:34:00Z")
As Seldon points out, the speed at which the sun rises and sets depends on the angle of the ecliptic with respect to the horizon. This angle changes over the course of the year. In fact, it changes slightly every day, and even between morning and evening of a single day. During the part of the year, spring, when the solar angle is increasing, this makes the sunsets slightly shorter than the sunrises. During fall, when the days are getting shorter, the sunset on any given day lasts a bit longer than the sunrise. ---
**Author:** ![Undead\_Dude](https://avatars.discourse-cdn.com/v4/letter/u/e19adc/32.png) [@Undead\_Dude](https://boards.straightdope.com/u/Undead_Dude)\ **Post date:** [June 3, 2002, 1:51pm UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/11 "2002-06-03T13:51:32Z")
> [@](#): > > \*Originally posted by Earthling \* > That being the case, the sun should appear to “rush” as it rises and “linger” as it sets (if I understand the [apparent sunrise & sunset](http://www.srrb.noaa.gov/highlights/sunrise/glossary.html#apparentsunrise) phenomenon correctly, that is). I don’t think that’s the case. The refraction is symmetrical over the top of the sky, so it shouldn’t cause a different effect for either side. It should cause it to “linger” for both sunrise and sunset. Of course the refraction is a very minor effect. ---
**Author:** ![hibernicus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hibernicus/32/2802_2.png) [@hibernicus](https://boards.straightdope.com/u/hibernicus)\ **Post date:** [June 3, 2002, 10:49pm UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/12 "2002-06-03T22:49:26Z")
> [@](#): > > \*Originally posted by Undead Dude \* > \*\*Of course the refraction is a very minor effect. \*\* I don’t think so. The sun’s disc subtends an angle of around half a degree. Atmospheric refraction depends on atmospheric conditions, but can easily “raise” the sun by half a degree. So the whole of the sun’s disc could be visible even when the elevation of the upper limb is zero. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [June 3, 2002, 11:20pm UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/13 "2002-06-03T23:20:33Z")
Depends on what you mean by “rush” and “linger.” The effect of refraction is symmetric - it raises the elevation of both the setting and the rising sun. Which means it slows down the movement of both when close to the horizon. So the sun appears to accelerate as it goes up, and decelerate as it goes down. ---
**Author:** ![Undead\_Dude](https://avatars.discourse-cdn.com/v4/letter/u/e19adc/32.png) [@Undead\_Dude](https://boards.straightdope.com/u/Undead_Dude)\ **Post date:** [June 4, 2002, 12:34am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/14 "2002-06-04T00:34:04Z")
I am sure that linger was meant to mean “spend more time in that area”, since the point was about whether or not refraction could cause the sunset and sunrise to happen at different rates. The symmetric nature of the refraction means that it would not have that type of effect. ---
**Author:** ![dwc1970](https://avatars.discourse-cdn.com/v4/letter/d/a183cd/32.png) [@dwc1970](https://boards.straightdope.com/u/dwc1970)\ **Post date:** [June 4, 2002, 4:34am UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/15 "2002-06-04T04:34:04Z")
Where’s **Bad Astronomer** when you need him? ---
**Author:** ![Earthling](https://avatars.discourse-cdn.com/v4/letter/e/90db22/32.png) [@Earthling](https://boards.straightdope.com/u/Earthling)\ **Post date:** [June 4, 2002, 4:27pm UTC](https://boards.straightdope.com/t/speed-of-rising-setting-sun/112069/16 "2002-06-04T16:27:06Z")
Evidently I misunderstood the apparent sunrise/sunset phenomenon. I drew out some diagrams and could not convince myself that it had any influence on the perceived speed of sunrises vs. sunsets. So until I get better information, now I think they both go at the same rate. It’s true, as has been pointed out already, that the time it takes for the sun to rise/set varies based on season and latitute. Basically, the farther away from the equator & the equinoxes, the longer it takes (the sun rises/sets at a narrower angle relative to the horizon). But within the span of a day, the variance won’t be noticeable.