This year will be the first full moon this century to occur on the winter solstice, December 22, commonly called the first day of winter.
A full moon on the winter solstice, occurring in conjunction with a lunar perigee (point in the moon’s orbit that is closest to Earth), will appear about 14% larger than it does at apogee (the point in it’s elliptical
orbit that is farthest from the Earth). And since the Earth is also several million miles closer to the sun at this time of the year than in the summer, sunlight striking the moon is about 7% stronger making it
brighter.
Also, this will be the closest perigee of the Moon of the year since the moon’s orbit is constantly deforming. If the weather is clear and there is a snow cover where you live, it is believed that even car headlights will be superfluous.
On December 21, 1866, the Lakota Sioux took advantage of this combination of occurrences and staged a devastating retaliatory ambush on soldiers in the Wyoming Territory. In laymen’s terms it will be a super bright full
moon, much more than the usual AND it hasn’t happened this way for 133 years!
Our descendants 100 or so years from now will see this again. I hope you folks find this interesting! Remember this will happen December 22, 1999. Let’s hope the weather cooperates. Enjoy your moon.
*boli: They announced on the radio this morning that this is NOT TRUE. It’s been going around via e-mail for awhile, and it’s just another urban legend. *
So the Injuns ain’t attackin’?
I looked in the mirror today/My eyes just didn’t seem so bright
I’ve lost a few more hairs/I think I’m going bald - Rush
Ooh! The battle of the internet vs. the radio as the definitive source of wisdom unfolds.
Of course this is all moot for me since I live in and around Seattle and their is essentially a zero percent chance that the sky will not be cloudy that night or any other night till spring. But I’ll look for a brighter spot than usual in the clouds!
“If ignorance were corn flakes, you’d be General Mills.”
Cecil Adams The Straight Dope
curious george: And since the Earth is also several million miles closer to the sun at this time of the year than in the summer, sunlight striking the moon is about 7% stronger making it brighter.
The Earth’s apogee is 93 million miles. For the Sun to be 7% stronger, the Earth would have to have a perigee of 89.9 million. That’s about 1.1 million less than it actually is.
Two million miles is hardly “several million”.
I looked in the mirror today/My eyes just didn’t seem so bright
I’ve lost a few more hairs/I think I’m going bald - Rush
I read about this in Discover magazine a couple weeks ago. It is the combination of all three things that makes this time special. Discover didn’t say anything about the Indians, though.
I found an article about this at the SNOPES website (don’t ask me, I’m still trying to figure out if it’s an acronym or what?) I check there and The Straight Dope several times a week. It helps maintain my fasçade of superior intelligence when in reality my IQ and my shoe size are very similar (I have big feet).
Sky & Telescope is more skeptical of this email. They say there have been three other years since 1866 where the moon came closer to the Earth than it will this Wednesday. Also, they say “The difference in brightness will be exceedingly slight”.
However, they say “It is true that there is a most unusual coincidence of events this year…Ocean tides will be exceptionally high and low that day.”
On the other hand, The Farmer’s Almanac supports this email pretty much. They say "During this time of proxigean tides [unusually high tides due to the Moon’s
phase and proximity to Earth], coastal flooding could occur if there is one
more little extra effect, such as a storm at sea, on-shore winds, or low barometric pressure. The situation is primed for damage.
If the solstice night of December 22 is calm and cloudless, with the full Moon beaming down on a blanket of snow, it will be irresistibly attractive, and electrical illumination – even your car’s headlights – may seem superfluous. Let’s hope for clear weather.
*We did find that on the night of December 21, 1866, the Lakota Sioux staged a
devastating retaliatory ambush of soldiers in the Wyoming Territory – perhaps planning the attack for that bright night, whose lunar confluence was identical to this year’s".
So this is what I’ve been wondering: On that night I’ll be flying directly from Calgary, AB to London. We’ll probably be flying more or less over the Arctic and Greenland, so will I get to see the ice and snow all lit up by an exceptionally bright moon? I am very excited about this flight, I’ve never really left North America. I’ve already claimed the window seat, even though everybody has been telling me that I won’t be able to see a thing.
But does the moon even rise in the sky above the Arctic Circle in the middle of winter if the sun doesn’t?
As near as I can tell the moon will not rise that high on that date. The apparent path of the sun in the sky is called the ecliptic. The moon and the other planets in the solar system move in orbits that are very close to the ecliptic. The moon’s orbit, in particular, is inclined only five degrees from the ecliptic. Without doing the math I would guess that’s not enough variation to have the moon visible on days when the sun’s not.
The little reference book I’m looking at tells how to calculate the moon’s position for any date (“Practical Astronomy With Your Calculator”!) but I’m not going to. I will try to find an ephemeris online, though, where someone has done the calculations already. (And, importantly, done them right.)
Let’s see. I lathered and I rinsed. But did I repeat?
The declination of the moon on that date is right around 20 degrees north. Anything greater than zero would be visible from the North Pole, so the moon will be very much in evidence above the Arctic Circle that night.
The declination for the sun on that same day is -23 degrees, it’s maximum (negative) value, which is what makes it the solstice. So the sun and the moon are about 45 degrees separated north and south. That’s what I get for trying to do spherical trigonometry in my head.
Let’s see. I lathered and I rinsed. But did I repeat?
Also be sure to keep your eyes open for the northern lights. I once saw it from a plane, it’s a pretty impressive sight! Then again, the bright moon could spoil your view of that.
