Googling is failing me. I can find a lot of sites saying 05:04 UTC, but I’m looking for accuracy to the second. I’ve tried using this page, but I must be doing it wrong, because I am getting a result of 09:43:32, which is obviously way off.
This site: Stellafane Equinox & Solstice Calculator
calculates the time as: Fri Jun 21 2013 01:03:36 GMT-0400 (Eastern Standard Time)
I haven’t had any luck using NASA’s ephemerides generator http://ssd.jpl.nasa.gov/horizons.cgi
as it only goes down to minutes.
Where does that page give the time of the solstice?
Thanks, Coriolanus.
I was trying to imitate the procedure on this page.
I used the settings below and looked at the PAB-LON field, because it was the closest match to the longitude field that the guy on Yahoo Answers used. With trial and error I arrived at what seems to be a totally incorrect answer.
Ephemeris Type [change] : OBSERVER
Target Body [change] : Sun [Sol] [10]
Observer Location [change] : Geocentric [500]
Time Span [change] : Start=2013-06-21 09:40:32, Stop=2013-06-21 09:50:32, Step=1 m
Table Settings [change] : defaults
Display/Output [change] : default (formatted HTML)
It’s not noon?
Well it is if you’re somewhere like Cambodia.
It’s a particular point of the Earth’s orbit, not Earth’s rotation.
Can you really define the solstice to within a second, when you’re talking something as big as the earth? I suppose you can theoretically.
Edit: I suppose the solstice is defined by the plane of the Earth’s tilted axis, which has zero width, right?
No doubt there is some vagueness to it. Earth is not a perfect sphere, I imagine it wobbles slightly on its axis, etc. But these are very small imperfections.
:dubious: “Everywhere”?
Didn’t you hear?
We’re shipping all the Australians, New Zealanders, (most) South Americans, and south Africans up to the Northern Hemisphere and throwing a massive kegger.
Instead of PAB-LON (Sun-Target-Observer angle), I believe you should use “Observer ecliptic lon. & lat.” By definition, the Astronomical Summer Solstice (Northern Hemisphere) occurs at the moment the Sun’s ecliptic longitude is 90 degrees:
I used the following settings and narrowed the solstice down to UTC 05:03:58.23
Ephemeris Type [change] : **OBSERVER
**Target Body [change] : Sun [Sol] [10]
Observer Location [change] : Geocentric [500]
Time Span [change] : Start=2013-06-21 05:03:57.73, Stop=2013-06-21 05:03:58.73, Intervals=**2
** Table Settings [change] : QUANTITIES=31; time digits=**FRACSEC
**Display/Output [change] : default (formatted HTML)
Ah, I didn’t look at the Table Settings section. I wonder who’s right, you or Coriolanus’s page? Wouldn’t want to be one of those druids at Stonehenge sacrificing a goat twenty seconds too early.
This confuses me, since they always say it’s when the sun is highest overhead. Well, obviously, it’s not going to be the highest overhead everywhere in the world at the same time, so I always thought the solstice was also rotation based (as scientists can define terms however they want).
The “when the Sun is highest overhead” definition is clearly flawed, since equatorial regions will have two dates when that happens, one each before and after the solstice. A better definition would be that it’s when the Sun is at maximum declension, and that doesn’t depend on where on the Earth you are.