Talk:Sunrise
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[edit] Why is Date of Most Extreme Sunrise / Sunset Not Solstice?
The page mentions that the date of the most extreme sunrise or sunset in the year does not fall on a solstice. For example, in the Northern hemisphere sun rises at its latest time in early January, NOT on December 21st. Why is this?
Ozonevibe 14:26, 20 January 2007 (UTC)
The phenomena the dates of latest sunrise and earliest sunsets differing from the solstices is due to several factors. The major influences are your latitude (how far North or South of the equator you live), the tilt of the earth's axis, and the non-circular orbit (elliptical) of the earth around the sun.
Since the earth is tilted roughly 23 degres relative to the plane of earth's orbit around the sun, your latitude determines when the sun rises and sets. The further you are from the equator, the more pronounced the effect. So, the greatest effects of latitude are experienced at or around the Solstices and the effects are largest at the greatest latitudes: e.g. the winter days are shortest at the North Pole and longest at the South Pole - and the effect is reversed in the summertime (from a North American or European perspective, that is - an Aussie or Kiwi may beg to differ).
The elliptical orbit of the earth around the sun reaches it maxima at the solstices. Since the earth rotates counter clock-wise, (anti-clockwise, when viewed from above the North Pole), and the orbit of the earth around the sun is also anti-clockwise (counter-clockwise), (when viewed from above the North Pole) the latest sunrise (for the Northern Hemisphere) appears after the earth has passed the point of Winter Solstice (early January in the Norther Latitudes): from the perspective of the Sun, the longest path to the earth at dawn, (the leading edge of illumination), is when the earth's position is to left of the Winter Solstice maxima, and that outside radius of the earth's roatitonal path is furthest from the sun. The same effect occurs for the earliest sunset, as the "last" rays of the sun reach the earth, the longest path occurs when the earth is to the right of the Winter Solstice, (before the Winter Solstice occurs), giving the longest path between the Sun and the point(s) of sunset(s), where the outside radius of the earth's orbit is furthest from the sun.
Reverse the phenomena for Summer Solstice or for observers in the Southern Hemisphere.
The last factor, since momentum must be conserved, the earth's radial velocity increases slightly as it passes through the ends of the ellipse - a ball travels faster as it goes through the tight curves of a closed track than it does through the straighter sections.
One other inter-related perspective: Why is winter colder than summer, especially at the higher latitudes? At mid-day, the northern hemisphere is tilted most directly towards the sun during the summer - and since the energy of radiation decreases as the reciprocal (in direct proportion to) of the distance squared: e is proportional to 1/[(distance between radiater and observer)x(distance between radiater and observer)], even small changes in distance turn into larger changes - or if you move twice (2x) as far away from the sun, the light energy you receive drops by 4 fold (4x). So, that 23 degree tilt of the earth's axis has a significant effect on temperature changes between seasons and on the when the earliest/latest sunrises and sunsets occur.
201.160.119.29 19:58, 24 January 2007 (UTC)The Good Doctor Fry201.160.119.29 19:58, 24 January 2007 (UTC)
Thanks for that. There's some things not quite right: "the earliest sunrise (for the Northern Hemisphere) appears before the earth has reached the point of Winter Solstice (early December in the Norther Latitudes)".
The earliest sunrise occurs near the SUMMER solstice, not the winter solstice. It's the earliest SUNSET that occurs in early December in Northern latitudes. Similarly "the same effect occurs for sunset ... (after the Winter Solstice occurs)" - it's SUNRISE that reaches it's most extreme (latest) time AFTER the winter solstice.
There is some information that explains the phenomenon of extreme sunrise / sunset and solstice covered in the Wikipedia article "Equation of Time". However, a lucid explanation for the layman is still hard to come by (I know it's crazy talk, but what about one of you guys who understands it putting up some diagrams?) Ozonevibe 20:23, 30 January 2007 (UTC)
Thanks for the correction, you are correct, I clumsily described it for the earliest sunrise = inadertantly describing it for the Summer Solstice. Please see my revised answer above - I've corrected (reversed) my terminology to appropriately describe the main reason for latest sunrise and earliest sunsets. e.g. the physical positions of the earth relative to the sun and the Winter Solstice (for the Northern Hemishphere) cause the latest sunrise to occur when the your latitude has the longest path between the sun and leading edge of illumination = sunrise, and this occurs after the earth has passed the Winter Solstice. oooops! Thanks for your patience. 201.160.119.29 18:46, 5 February 2007 (UTC)The Good Doctor Fry201.160.119.29 18:46, 5 February 2007 (UTC)
[edit] Difference Between Sunrise and Dawn
Is there a difference between sunrise and dawn? If so, this should be explained. - Montréalais
How do temperature and pressure affect the optical illusion of true sunrise? Rhoneyman 13:36, 5 February 2006 (UTC)rhoneyman
- I dont thik that there is any ref'rence
[edit] sunrise and "moonrise"
Is there a westward revolution of the moon around the Earth, the same as there is an apparent revolution of the sun around the earth?? In other words, is it correct to think that the Moon rises on the East and sets on the West, the same as the Sun does?
--70.111.35.126 07:23, 13 November 2006 (UTC)M.
- I think so. --Spoon! 09:56, 13 November 2006 (UTC)
Yep, it sure appears that way to millions of us here on Planet Earth, past and present. If it interests you, look up information on the seemingly-peculiar orientation of ancient Native buildings in the Chaco Canyon area. This group seems to have understood the cyclical nature of the position of the moon's rising and setting as well as any of the other ancients. My memory is aging, but I believe that there is roughly an 18-19 year cycle in the relative positions of moon-rise on the eastern horizon and and moon-set on the western horizon, and the folks that laid out many building positions in the cities of Chaco Canyon oriented their East-West walls to point directly to the most extreme northern and southern moon-rise points on the Eastern Horizon. (Hint, don't feel bad, since the period of the cycle is relatively long at 19 years, and most of us aren't aware of such things till age 15-20 - which means that we only get to witness the extremes 3 or 4 times in a lifetime.) "yep, Ah r'member back in '91 when the moon rose way in thuh south." not really... 201.160.119.29 20:21, 24 January 2007 (UTC)The Good Doctor Fry201.160.119.29 20:21, 24 January 2007 (UTC)
[edit] Link suggestion
I would like to suggest the following link to a sunrise / -set calendar with interactive location finder. As I am the site admin, I find it correct, not to set the link by myself. But maybe someone find it worthy: sun.exnatura.org --XN 13:13, 3 December 2006 (UTC)
- I think, I will give it a try since it's not commercial and GFDL'ed. --XN 20:25, 8 December 2006 (UTC)
[edit] Distinguishing Sunrise - Sunset
Is there a way to distinguish sunrise from sunset in pictures for instance? Is there something that can indicate whether a picture is one of the other? I came to Wikipedia looking for this but didn't really see it as part of this article. --Renrenren 16:06, 29 January 2007 (UTC)
- Well, you can see the sunrise while looking east and you can see the sunset while looking west. Thug outlaw69 16:36, 13 February 2007 (UTC)
- There's a smart one in every bunch. --Renrenren 18:23, 13 February 2007 (UTC)
While Thug's answer might seem flippant at first, (s)he actually fingered the truth. Unfortunately, for existing photos where there is no context to prove which way the view is oriented, it might not be possible to "prove" they are correctly labeled. One solution would be to photgraph the sunrise or sunset near a coastline with the ocean in the background, and with a famous landmark visible to the left or right in the foreground. The landmark would provide a verifiable reference, and the ocean would give the cleanest possible horizon for the sun. (Providing the latitude and longitude of both the landmark and the spot where the camera was placed would facilitate verification.)
Of course this means the following:
- new photographs would need to be obtained to add to the Wikipedia
- Sunrise would have to be photographed on an east coast of whatever country
- Sunset would have to be photographed on a west coast of whatever country
This solution would also apply to movies of sunrise or sunset, to preclude someone claiming the movie is being run backwards.
Sunrise and sunset photos from a variety of countries might make for a very interesting gallery.
Badly Bradley 02:25, 15 February 2007 (UTC)
[edit] Link suggestion
Hi Guys. Some time ago I wrote a Java 3D Earth to provide a day/night view of the Earth, calculate sunrise/sunset and first-light/last-light times at the cursor location. Users can adjust the time to see the view of the Earth at that time. It clearly shows current areas of the Earth in daylight as lighted, between sunset and last-light as shaded, then after last-light as dark (using night image of the Earth). I think it helps provide a clear, interactive view of the Earth in relation to the Sun. It is free for people to use.
It is a 3D program and consequently requires a 3D graphics card and a real language. I used Java 5 to write it since Java runs on most platforms. It also runs in a web page as an unsigned applet (it's even a gadget on iGoogle) or on your desktop. I don't know if this is considered useful enough to Wikipedia readers to warrant a link. I will let someone else evaluate and make that decision. You are free to link to the site if you decide it is worthy.
[1] Sapphireman (talk) 12:20, 17 January 2008 (UTC)
[edit] Images
I think that the bottom two images of sunrises in New York State are a bit redundant. Perhaps we could replace one them with a sunrise outside of the U.S.?
[edit] Colors and Mie scattering
As in sunset, I've removed the language about Mie scattering from the explanation of sunrise color, and replaced it with the conventional explanation surrounding Rayleigh scattering. The Mie scattering material here and in sunset was the sole work of Dr. Steven Fry in October 2006, and it looks like it was just a misunderstanding. Spiel496 (talk) 22:08, 13 April 2008 (UTC)
