Brightest Moon Fallacy

theLunchLady writes "Unfortunately, on 22 December 1999 we will not behold the brightest moon in 133 years. An article in Sky and Telescope dispels this myth. BTW: the story about the American Indians conducting a raid under this moon 133 years ago, because it was so bright, is also a myth; the raid was conducted while that big fiery thing was in the sky. " While I'm unqualified to comment on both comments, I'm sure some of you have comments.

local moon IS brightest

Last night/this morning I woke up and thought "Wow, that moon really is bright", and went over to the window. It took me a few seconds to realize that it was my neighbor putting up Christmas lights, with the help of a 500 watt halogen work light aimed right at my window.

It'll still be "brighter"

As the article points out, the moon will still be at perigee (closest point in its orbit to the Earth) and it will be about 19% brighter than usual. To most of the people (who have received this email, and I know I've gotten it seven times so far) looking at the moon, this will not make a big difference. Full moons are always bright, and so they might *think* it's a lot brighter and then not bother to look next month to compare. Personally I observe the moon every month (leftover habit from astronomy classes) and I have noticed the slight difference, but yeah, it doesn't merit the bandwidth that's been wasted on this.

I still think it's neat to have a full moon on the Winter Solstice, though :)

.. In Discover tho?

I didn't get the news by any email'd farmers almanac. I read it in last months issue of Discover.. now I'm not going to say they didn't pick up the scent somewhere, but another accredited agency has the other side.

You choose who you want to believe.

Malachi

Oh ye of little faith

From Sky and Telescope: "Most people won't notice a thing, despite the e-mail chain letter that implies we'll see something amazing."

Call me cynical, but I bet that most people who've gotten the email will see that the Moon is brighter than usual ... because they expect to. Humans are notoriously poor observers, and will often see what they expect to see, whether it's there or not.

On the plus side, maybe a few more people will remember to look up. Maybe it's partly because I live in a city, but sometimes I think I'm one of the few people who ever notices the sky.

Brightness is relative

Okay, maybe this isn't going to be the brightest moon of all time. I'm sure that the original information upon which the story that this refers to never claimed it would be. However, for those of us who are blessed with a clear sky tonight, the full moon should be brighter than we typically experience during a normal month.

As far as stories of secret indian attacks carried out by the bright light of the full moon, it is about as plausable as the story about the Space Shuttle size being dictated by Roman Chariot wheel spacing. Sure, it sounds like a neat explaination, but that doesn't make it right. I'm not qualified to say whether its wrong.

Regardless of the relative brightness of this full moon, I doubt if I will get to see it, based on the local weather. Anyway, this isn't the full moon I care about. Its Next Month's full moon that is something to look at. That is when we get to see a Total Lunar Eclipse. This event occurs on the evening of January 20, between about 9:30 pm EST and 2:30 am EST., with totality lasting from 78 minutes between about 11:00 pm EST and 12:20 am EST. Be sure not to miss this one, because we won't see another one in the us until May 16, 2003.

Mike Eckardt [geocities.com] [e-mail]

I'm so alone...

I haven't recieved the Full Moon Forward yet. I feel so isolated and lonely :)

On the other hand, I have recieved Elf Bowling *seven* times, The Elf-Bowling-Is-A-Virus thing twice, and Christmas Carols for the Mentally Deficient 4 times.

I think junk email distribution patterns would make an interesting area of study for Information Theorists :)

Dana

You can't trust everything you read

What amazes me is how people continually will believe anything they find in their inbox or on a web page. Our parents, our friends, even the news media (does anyone remember the Arizona news station that reported on a "Good Times"-like virus warning they got in their mailbox?)

It seems so obvious, but so many people are led to believe that if it's in print and sounds semi-official, it must be true. People believe unless they have a reason to doubt, and on the net you don't survive unless you do it the other way around.

Not just the moon, Santa's test run too

The brightness will also be from Santa giving his test run about the sky. He'll probably be going about in his excercise clothes, shorts and tank-top. Due to the cold at the north pole, Santa will be white as a ghost, and make an excellent reflective surface to add the extra bit of brightness.

Everyone's got it all wrong?!

See, I saw the e-mail and thought, 'Wow, what a funky hoax!' But then I realized that the e-mail is partially true. What's really the fact here is that this is indeed (at least in the northern hemisphere) going to be the darkest night. Why? Well, the night will be the longest of the year and thus, darkness will have a chance to soak in and penetrate everything. Couple this with a new moon and the moon becomes even brighter, because as everyone knows, light objects on a dark field are lighter than the same shade object on a lighter field (it's a perception thing). Thus, it's really about the darkest night of the year.

As for the Indians, I thought the US's Thanksgiving was last month.

Non-executable email viruses: memetic parasites

If you've been amused to see this and other email chain-letters mutate and reproduce - propagating in spite of their bullshitical nature - you might want to look into the emerging science of memetics [lycaeum.org] and how it is applied to urban legends [lycaeum.org] and to chain [vub.ac.be] letters [silcom.com] .

It is easier to understand the proliferation of messages that communicate ideas that are contrary to the intent of their proliferators (in other words, people think they're spreading legitimate information but in fact are talking crap) if you see these communications as the result of natural selection rather than conscious creation.

It's the same principle that has allowed us to make much more sense out of the natural world by trying to understand it as the product of evolution, rather than trying to interpret it as the residue of God's Plan.

Re:What about the tides?

For those of you who don't know, Excite [excite.com] lets you add tide tables as part of their customization. This is what mine currently looks like:

Old Saybrook Point, Connecticut Tides
December 21
Low3:25PM -0.50
High9:27PM3.08
December 22
Low3:23AM -0.31
High9:49AM4.11
Low4:23PM -0.58
High10:28PM3.11


These don't appear to be all THAT unusual to me at all....





This is my opinion and my opinion only. Incidentally, IANAL.

Explanation

It is a common misconception that the winter solstice is on the day that the Earth is at perihelion (closest approach to the Sun). Actually, even more common is the belief is that the winter solstice is the day that the Earth is *farthest* from the Sun, but that's another matter.

Anyway, "Perihelion Day" is actually sometime around the second or third of January (S&T's skygazer's almanac can tell you). This puts the Earth-Moon system closest to the Sun. The closer to a luminous object you are, the more of that object's light impacts your surface.

During a full moon, the moon is directly opposite of the Sun (from Earth's point of view). The day in which the bodies line up Sun-Earth-Moon (ie. full moon) on which the Moon subtends the largest solid angle of the Gaussian sphere centered on the Sun is on "Perihelion Day". Making the assumption that the Moon's albedo is constant (a pretty good one), this is the set of circumstances that will maximize the amount of reflected sunlight from the Lunar surface.

Thus, I believe the guys at Sky & Tel. After all, Discover is a general science/technology magazine. S&T specialize in this stuff.

Eric

syzgy xyzzy!

Not since 1866 have a full moon, the winter solstice, and lunar perigee been bunched so closely in time, within ten hours of each other. The Earth, the sun, and the moon will be in a straight line and the moon will be in perigee, circumstances that produce the highest tides.

The situation is called a perigean syzgy, and it has dramatically affected weather patterns in coastal areas in the past. Storms that reach the coast during these times of unusually high tides have been known to cause sizable storm surges.

But it'll still be pretty bright...

A bright moon. Whoop-dee-doo.

"To the average person, it's just going to be another full moon," said Bob Bonadurer, director of the Minneapolis Planetarium.

That is from an excellent debunking and explanation of this e-mail, which can be found here [simplenet.com], at the Urban Legends Reference Pages [simplenet.com], an excellent source of well-researched debunking. (I was a couple of days shy of being the first one to debunk the violent kangaroo myth [simplenet.com].)

Apparently, the last time the moon was at perigee during the full moon was...last month. It just wasn't the solstice.

Like I said, whoop. Dee. Doo. (I'll have to at least take a look anyway...I actually set my alarm to get up in the middle of the night to watch the Leonid meteor shower, which turned out to be a total bust.)

Moon cycles

Actually, I'm at the UC San Diego talking to Professor Jakobson right now. He's the head of the astronomy department here, and tells me that the moon tomorrow will, in fact, be naked and petrifiend. There is also a slight chance that it may pour scolding-hot grits down it's pants. The Romans first witnessed this event and called it "Natalie Portman" -- today we know it as "Meept".

-----------

"You can't shake the Devil's hand and say you're only kidding."

Signing away your worldly belongings...

Strange that you mention this. During the solar eclipse last summer, there was that bizarre cult built around a strange piece of computer software. The members of this cult did exactly that: many signed away most of their life savings to an obscure startup in North Carolina. Some even got upset when said startup wouldn't accept their pagan gifts.

Of course not...

Photons are just a fake concept to hide the truth from the common man. Light is just the absence of dark. Dark is spread by sub-atomic particles called "darktrons", and the effects you observe are easily explained. What we know as "lights" are really only darktron suckers. They remove the darktrons in a straight line from where they are. This is why you can put a piece of wood between you and the "light", and it is darker on your side - you are creating a dam for the darktrons. The "bending of light" effect is also explained by darktrons. The sucking power of these "lights" (notably the Sun) is strong enough to even pull some darktrons from around corners, which creates an slightly curvi-linear pattern. This is just another conspiracy by "The Man" and his white-lab-coated minions to deprive us all of the truth!!!

So his comment about dark "soaking in" is perfectly ok - since the darktrons take time to replenish - in super slow motion you can actually see the dark making its way back towards the "light"... foolish mortals

8^)

Of brightness and magnitude

Yes, the moon will be 20% brighter than it has been in the last 60-odd years. This would be all the more interesting if the human eye reacted to light linearly, rather than logarithmically. (1/5th brighter... wow! Right? nope...)

The moon has a "normal" magnitude (estimated brightness the eye perceives) of about -16.9 (the smaller the number, the brighter the object; the sun is magnitude -26.8).

Increasing that by 20% - heck, let's be generous, 30% - gives us a difference in magnitude of roughly .3 (mA - mB = - 2.5 log (IA/IB)).

So the apparent change in the moon's brightness - in its magnitude - will be from -16.9 to -17.2. This difference IS linear, so I'll let you do the math - not one heck of a difference, and not really enough to be seen with the naked eye.

Just thought I'd clarify :-)