Google couldn’t help me here. I was just watching the Susan Sarandon TV movie set at the South Pole, and the comment that the South Pole only has one sunrise and one sunset per year got me to wondering:
Is there enough angular separation between the sun and moon at high latitudes that an eclipse of the sun (by the moon) can never be total?
If so, what’s the highest latitudes that can experience a total eclipse?
Look at it this way. Every new moon, the Earth passes near the shadow of the Moon. But note that eclipses of the Sun are much rarer than that. Ask yourself why? Because the Earth misses completely passing thru the shadow. This directly tells you that the shadow of an eclipse isn’t limited by latitude since the shadow isn’t even limited to the surface of the Earth at all.
Eclipses can occur at any latitude. In 2000 there was a partial eclipse at the South Pole. I’m not aware of any total eclipses there since we’ve established the scientific base, but it wouldn’t be unusual if there weren’t any–any given spot on Earth only experiences a total eclipse on an average of once every 360 years.
Total solar eclipse, November 2003, visible from Antarctica
I think you guys are missing the real question which would be weather the shadow of the moon can cover then entire planet Earth simultaneously. Obviosly it can cover any point at any one time but how about all at once?
The diameter of the moon is 2160 miles. So the penumbra (where a partial eclipse is seen) is at least that wide. The exact extent will be a bit wider because the shadow hits the earth obliquely everywhere except when the umbra is on the equator.
On re-reading the OP I am now not sure what the question is but, if it is strictly if there can be an eclipse in the poles, the answer is there can be an eclipse anywhere, even in a spaceship outside the earth. If you are in the shade cast by the moon you are seeing an eclipse and most of the time that shadow is outside the earth.
If the question is whether the shadow can cover the whole earth at once then the answer, as rowrrbazzle points out, is that it does not even come close. The shadow of the moon follows a path across the surface of the earth and is seen at different times in different places. You can find maps with these paths on line.
sailor, I’m asking if the poles can experience a total solar eclipse. Earthling’s link doesn’t answer that.
Think about my OP this way. You’re standing on a sidewalk. Several yards away from you is a utility pole; several yards beyond the pole is Uma Thurman.
You, the utility pole and Uma are all in a line, so you can’t see her. But you’re with two friends; one is standing five feet to your left and the other is standing five feet to your right.
Each says, “Whoa, sailor, check out Uma over there!” because their line of sight to Uma is not blocked by the utility pole. You want to know what the heck they’re talking about, because you see no Uma anywhere.
Now, replace the utility pole with the Moon, Uma with the sun, yourself with the Equator and your two friends with the North Pole and South Pole.
Are the Poles far enough from the line joining the sun and Moon, that the view of the sun can never be fully blocked by the Moon at those latitudes?
Ok, I think I get it, the observer at the poles is a distance from the moon greater than the observer who has the moon overhead and the question is if that incresed distance makes a difference in whether the eclipse is total or not. Right?
Note that the observer who sees the moon on the horizon, no matter where on earth he may be, is in the same position. Being at the poles makes no difference really.
In any case, the answer is that yes, an observer who sees the moon low in the sky can see a total eclipse.
If you look at the map on Earthling’s link, I think it does answer your question. The red swath across Antarctica is the area that will see a total eclipse. The rest of the grid area will see a partial eclipse, and the rest of the world will see none.
A total eclipse at the equator will not be visible at the poles, per your Uma/pole illustration. But eclipses can be centered anywhere on (or off) the earth.
No, Skammer, I saw the swath indicating a total eclipse. It doesn’t answer the OP because the swath does not cross the South Pole. It illustrates only that that particular eclipse wasn’t total at the Pole; not whether a total eclipse is possible at the Pole.
That said, sailor’s latest post clears up the issue for me. Thank you.
I will note that an observer who sees the moon on the horizon is at the same distance from the moon as if he were located at the center of the earth and that is the basic point of calculations. As the observer moves closer to point where the moon is overhead (GP) the apparent diameter of the moon increases and this effect is called “augmentation”. The effect of augmentation on the semidiameter is about +0.2 seconds of arc (from 15.9 to 16.1 as a general average) when the moon is overhead.
I am posting a couple of tables I designed myself for use in astronavigation. They give the semidiameter of the sun and moon to the closest tenth of an arcsecond. The sun as a function of the time of year and the moon as a function of Horizontal Parallax (both HP and semidiameter are directly related as they are e function of the distance earth-moon) and of the observed height of the moon over the horizon. You can see that the moon’s SD on the horizon often exceeds the minimum sun’s SD which is 15.7’ in summer.
Moon SD + Aug.
0 20 40
HP <Ha< <Ha< <Ha<
20 40 90
53.9
14.8 14.8 14.9
54.2
14.9 14.9 15.0
54.6
15.0 15.0 15.1
54.9
15.1 15.1 15.2
55.3
15.2 15.2 15.3
55.6
15.2 15.3 15.4
56.0
15.3 15.4 15.5
56.3
15.4 15.5 15.6
56.7
15.5 15.6 15.7
57.0
15.6 15.7 15.8
57.4
15.7 15.8 15.9
57.7
15.8 15.9 16.0
58.1
15.9 16.0 16.1
58.4
16.0 16.1 16.2
58.8
16.1 16.2 16.3
59.1
16.2 16.3 16.4
59.5
16.3 16.4 16.5
59.8
16.4 16.5 16.6
60.2
16.5 16.6 16.7
60.5
16.6 16.7 16.8
60.9
16.7 16.8 16.9
61.2
16.8 16.9 17.0
61.6
16.9 17.0 17.1
61.9
15.9 16.0 16.1
58.4
16.0 16.1 16.2
58.8
16.1 16.2 16.3
59.1
16.2 16.3 16.4
59.5
16.3 16.4 16.5
59.8
16.4 16.5 16.6
60.2
16.5 16.6 16.7
60.5
16.6 16.7 16.8
60.9
16.7 16.8 16.9
61.2
16.8 16.9 17.0
61.6
16.9 17.0 17.1
61.9
Sun SD
1-Jan
16.3
29-Jan
16.2
1-Mar
16.1
23-Mar
16.0
13-Apr
15.9
5-May
15.8
5-Jun
15.7
31-Jul
15.8
31-Aug
15.9
22-Sep
16.0
12-Oct
16.1
4-Nov
16.2
4-Dec
16.3
31-Dec
Are you going somewhere?
Not really but celestial navigation has been a hobby of mine for some years now and I even taught some classes. All is done manually (no calculator or computers) using Almanac and tables and I designed my own forms and tables which work best for me. Those two tables are part of that.
And while we are here I will point out the moon is close enough that it appears to be in different positions in the sky for observers in different places on Earth and that is what the HP refers to.
This is only tangentially related to the OP, but it’s an obscure fact about solar eclipses and latitude, so …
One conventional starting point for the history of science is Thales of Miletus predicting an eclipse. Supposedly, he noticed the Saros cycle and used that to name the date. (As usual with ancient Greek science, every aspect of the story has actually been disputed by some specialist at some point …)
The idea is that eclipses occur when the sun, the moon and the lunar nodes line up, the latter being the points in the sky where the sun’s apparent path crosses the moon’s orbit. All of these move across the sky, but Thales is supposed to have noticed that they all come into the same relative positions every 223 months. Each eclipse is thus followed by one a Saros cycle later. Since the Saros cycle (at 18 and a bit years) is longer than the time between solar eclipses, one gets different Saros series, i.e. eclipses related by the cycle.
Except that the Saros cycle is just a close coincidence - in fact, it’s a coincidence involving three independent cycles. Because it’s actually slightly off, eclipses in a Saros series don’t quite repeat exactly. As a result, if you plot the paths of the different eclipses in the series, an interesting pattern emerges. You start off with an eclipse near a pole, then the next one (18 or so years later) is a bit closer to the equator, at a lower latitude. As the series continues, the paths move closer to the equator and then drift past it towards the other pole. Eventually they drift past it entirely and that particular Saros cycle ends.
So not only do solar eclipses occur at different latitudes, there are patterns in how they do so.
Bonzer, I believe the saros cycle does not mean the eclipse will occurr in the same place at all. It is just a cyclical repetition of the eclipses in time.
You’re correct, in that that the Saros cycle doesn’t involve the period of the earth’s rotation and so, even if it were exact, the eclipses wouldn’t happen in the same place. Or the same latitude (due to seasonal effects). The point is that, if the cycle were exact, sun, moon and node would line up in the same fashion on the celestial sphere (viewed from the centre of the earth) time after time and Saros series would be eternal. But it’s not, they don’t and they’re not. And the way this shows up is as a drift from pole to pole.
The are 3 types of solar eclipses: partial, total and annular. Annular is where everything lines up perfectly, except that the moon happens to be too far away, and therefore too small in angular diameter to completely cover the sun’s disk. (The moon’s orbit has quite a bit of eccentricity, ie not a circle but a pronounced elipse that has an apogee of roughly 440,000 km and a perigee of 360,000 km.
Since the poles are farther from the moon (on average) than the rest of the earth, I would think that they get more annular and less total eclipses than other places.
And as the moon and earth gradually move further apart, there will eventually be no more total solar eclipses - they will all be annular at best. So enjoy them while you can!