I was reading a book the other day, and it had a prophecy poem in it. One of the conditions was when the full moon is in the sky at noon to which my immediate response was “well there’s a cop-out - like that will ever happen”. Every one knows the full moon happens when the moon is on the other side of the planet from the sun, right?
But then I thought - what about Antartica? In the middle of winter you can’t see the sun at all, so I’d rule that out. Noon sort of asssumes you can see the sun. But in spring and autumn the sun is very low on the horizon at noon. A full moon would be very near (below?) the opposite horizon. But I know the moon appears to wander north and south during the year. What I don’t know and can’t find is whether the this would ever happen at the right time and with enough effect to make it rise above the horizon at noon.
In short, would there ever be a place and time on earth (presumably near the south or north pole) were the sun and full moon would both be visible at once at noon? Any astronomers want to have a go at this one?
Just a cite to show that a full moon occurs on different times of the day whether the sun or moon (or both) is up.
As for your question, think of standing at the North Pole. It’s almost the first day of Spring (March 20th). There is a full moon on March 25th. If you are on the North Pole, then you should be able to see both the Sun and full Moon on March 25th since the Earth’s tilt and revolution around the Sun will give the Northern Hemisphere longer periods of daylight (and daylight all day long at the North Pole). Also, for the next couple of years, the Moon is further north of the ecliptic than usual. This is cyclical since the Moon’s orbital plane around Earth does not match the ecliptic (Earth’s orbital plane around the Sun). I can predict with great certainty, that this coming full Moon can be seen with the Sun, from the North Pole (weather permitting!) as well as for the coming Spring and Summer months.
Oh, with the long days, I’m almost certain you can see the Full Moon and the sun at the same time if you go far enough north (or south) and pick the right time of year. The question is can you do it at noon? When the Sun is a high as it’s going to get (local noon), a Full Moon should be as low as it will get that day. Will the moon’s being further north than usual be enough to keep it above the horizon for a whole day? And still have the sun visible at all? I think would satisfy the criteria.
Well, after messing around with the Sky and Telescope Interactive charts, the full Moon is still below the horizon on the days of March 25th (21:00 GMT) and September 18th (2:01 GMT), where the Moon is just below the horizon, missing by about 6 or 7 hours when the Sun is still above the horizon. At 90 degrees North, I guess you can argue that Noon is happening at any time, but I stuck with GMT.
Now, I am downgrading my prediction to uncertain. Need more time to mess around.
On the North Pole, “Noon” happens 24 times a day since the time zones merge together at 90 degrees North and 90 degrees South (South Pole). I was trying to match the actual full Moon date AND time to fulfill the requirement, but I can say there are full Moon “days” (without regard to TIME of day) that the full Moon and Sun can be seen on opposite sides of the sky. March 22 and 23, 2016 was a better date for this to happen. By experimenting with the S&T Interactive, I have discovered that this can only possibly happen when there is a full Moon close to the spring and autumn equinox…but pinning down exact dates and time is a little tougher than I thought.
It’s not that the “Moon is further north of the ecliptic” for the next couple of years. It’s that the moon’s 5[sup]o[/sup] ecliptic tilt and the Earth’s 23 1/2[sup]o[/sup] axis tilt are now synchronized so that the "Moon in its monthly orbit swings through extremes of high and low declination. "
AWB:It’s not that the “Moon is further north of the ecliptic” for the next couple of years. It’s that the moon’s 5o ecliptic tilt and the Earth’s 23 1/2o axis tilt are now synchronized so that the "Moon in its monthly orbit swings through extremes of high and low declination. "
In other words, the Moon will reach further north of the celestial equator than it usually does—not the ecliptic.
Declination = distance north or south of the celestial equator
Latitude = distance north or south of the ecliptic (north-south with respect to the ecliptic poles, not the equatorial ones)
Just to throw in a different point… I would actually interpret that poem a little differently… yes, the moon cannot (ordinarily) be visible at twelve o’clock midday. But there are some interesting other definitions of the term ‘noon’:
1b: The… point in the sun’s path at which it is on the local meridian.
2: The highest point or zenith.
3: (Archaic) Midnight.
So, there is an archaic form which actually refers to midnight, and some precedent for extrapolating the idea of ‘noon’ to the point where any celestial body is nearing its highest point, zenith, or crossing the local meridian… which means maybe the prophecy refers to the full moon, high in the sky at midnight!!
Just thought I’d throw in that as a different perspective… especially since “the moon’s noon” is going to figure into a story that I’m writing myself, LOL.
YR:I can say there are full Moon “days” (without regard to TIME of day) that the full Moon and Sun can be seen on opposite sides of the sky. March 22 and 23, 2016 was a better date for this to happen. By experimenting with the S&T Interactive, I have discovered that this can only possibly happen when there is a full Moon close to the spring and autumn equinox.
Right. Disregarding the Moon’s latitude for the moment, what you need are conditions when two points of the ecliptic that are 180 degrees apart are both visible, because full Moon occurs when the Moon and Sun are at opposite points of the ecliptic.
Now, since the ecliptic and the plane of the local horizon are both great circles on the celestial sphere, and all great circles bisect one another, there are always going to be 180 degrees of the ecliptic below the local horizon.
So that means that the only two opposite points of the ecliptic that you can ever see simultaneously are the two points where it intersects the local horizon (the points called the “ascendant” and the “descendant”, to be technical).
But in the vast majority of cases, when the sun is at a point of the ecliptic on the horizon, it ain’t noon or anywhere near it! Rather, it will be sunrise or sunset. “Noon” means that the sun has risen above the horizon—except, as you discovered, at an equinox at one of the poles.
The fact that the Moon’s latitude generally takes it a little above or below the ecliptic complicates the geometry a little bit, but the short answer is still no, you can never see the full Moon at noon, at least not at any latitude where “noon” has any real meaning.
So yeah, your “prophecy poem” has failure built solidly into it.
I think that the restriction of “noon” to cases where the Sun is above the horizon and on the meridian is unfair. Take a jaunt to Barrow, Alaska in December and wait for the full Moon nearest the winter solstice. The Sun won’t be visible, but there will certainly be a noon–the clock will say noon, and twilight glow will be visible toward the Southern horizon. And the full Moon will be circling the sky all day, never setting, and shining low in the Northern sky at noon.
Based onthis drawing I don’t think it is possible to see both sun and full moon at noon. But it does seem that it is possible to see them both at midnight.
Noon is when you are on the side facing the sun and the sun is directly in the south. In that case if you position is as shown at noon, the full moon is hidden by the earth. Midnight is when you are on the side directly opposite the noon position and it looks like both sun and full moon would be visible.
The requirements for seeing both Sun and full Moon in the sky at noon or midnight are exactly the same. It must be near a solstice in the Arctic or Antarctic (summer for midnight visibility, winter for noon), so that both bodies will be near the horizon at the appropriate time. If they are exactly opposite in the sky, the lofting effect of atmospheric refraction will allow both to be visible just above the horizon. If not, you can choose a time when the full Moon will stray from the ecliptic in the appropriate direction (north in the Arctic, south in the Antarctic) to achieve even better visibility, with both bodies being as much as three degrees above the horizon at noon or midnight under optimal conditions.
Actually in a prophectic sense:
Emporer to Senate; The seers have spoken, when you see the fullness of the moon at noon, our enemies will be upon us.
Later that day; General what news have you, Your highness the barbarians are poised to attack tomorrow at noon during the eclipse.
King to his Generals; I see news travels fast!
Thanks for the clarification AWB and Kimstu…I should have thought things through a little better instead of posting little blurbs and retractions late at night…
I realize that exact opposition would create a lunar eclipse, but since that happens on rare occasions, the “full” Moon would have to be north or south of the ecliptic to miss the Earth’s shadow, thus creating the possibility of see both the Sun and the “nearly full” Moon. Also, it would be more plausible to see this at the South Pole rather than the North Pole due to altitude of the icesheet on top of Antartica (unless at 90 degrees south is totally surrounded by higher peaks…even a nearby peak is better than a valley at 90 south. Earth’s oblateness would counteract this, but I’m not sure how much. This would still have to happen very close to the spring and autumn equinox.
Kimstu, I think the answer should be yes, under certain circumstances, but I agree with you on the definition of noon at the poles…it really doesn’t have significant meaning at the poles.
Astronomers consider the moon to be “full” when it’s opposite the Sun. In a metaphorical sense, as GawnFishin suggets, one can see “the entire Moon” or “the fullness of the Moon” during a solar eclipse, since the entire disk is visible and backlit by the Earth. But astronomically speaking, it’s still a new Moon.