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About 5 yrs ago, when I used to cycle along a particular route regularly, it came to my attention that the sun used to set directly at the end of a certain road.
Fast forward to the present, and the sun is setting at the end of a different road.
What information do you need to establish where it will be setting 5 years hence?
Because the planet tilts on its axis and this angle changes throughout the year, where the sun rises and sets changes every day. When you noticed it setting on a particular street five years ago it was during the time of year that it would appear to be going over the horizon there. At some point this year it will (or already has) set there again.
Where it will rise and set on the solstices and equinoxes each year is calculable and people have been predicting that for a very long time. If you went outside and used some landmark as a visual guide or laid down stones on the ground to mark where the sun came up on, say, June 21st and where it then set at the end of the day, then if you went back to that spot exactly one year later the sun would rise and set in the same positions.
Luckily, now there are slightly simpler ways to do it than just waiting around for a year. I thought this explained it fairly well.
Cheers for that. I'm still going to try your experiment. :)
Your people have been doing this experiment for a long time.Quote:
Originally posted by ivan astikov
(cough, cough stone henge cough, cough)
So, if I was to camp within Stonehenge for a year, at specific times I would see the sun set behind each standing stone?
Not exactly, the sun will only set to the west south west. At the summer solstice it will set at its most northern position (just south of due west). At the winter solstice at its most southern. *Quote:
Originally posted by ivan astikov
The layout of most ancient calendars** where set up so that the altar would face the rising sum on the spring and fall equinoxes. With stones marking important times of the year for that tribe. Spring planting and fall harvest being the most important among them.
*This is only for locations with the same latitude as England. In the southern hemisphere the sun sets north of west. And at the Equator it sets almost due west all year.
**I am not sure of the exact layout of stone henge.
No.Quote:
Originally posted by Glazer
On the equinoxes the sun rises and sets on the prime vertical (Z=90, Z=270) everywhere on Earth. In the northern hemisphere the sun will rise and set closer to N when its declination is positive and will rise and set closer to S when its declination is negative. This effect becomes greater as the latitude of the observer increases. (To the point that is the observer travels far enough N the sun will not set at all because it is even higher than the northern horizon.)
Stonehenge is located at 51.1789 N, 1.8262 W and the sun will set with an azimuth Z= 310 (NW) on the summer solstice and Z=230 (SW) on the winter solstice and those are the extreme limits. It will rise with symmetrical bearings.