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Garrette
SFN Regular
USA
562 Posts |
 Posted - 01/31/2002 : 03:56:56 [Permalink]
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All you astronomers out there correct me if I'm wrong, but I'll give this a go, at least the apparently huge part (can't talk to the orange color):
This is more of an optical issue than a lunar or astronomical one.
It only appears huge when it is close on the horizon to something on earth.
You will notice that the moon never seems huge when it is in the open sky; it is only when it is apparently next to a mountain, a tree, a telephone pole, etc., that it seems to be larger than usual.
In the sky, there is nothing against which to judge the moon's size, but when a terrestrial object is in the same small field of vision, the comparison between the moon and the object makes you realize that the moon is, in fact, quite large.
So I suppose the real question is the reverse of the one you asked: Why doesn't the moon seem huge when it's in the open sky? Because there's nothing to compare it to.
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Humbly awaits all corrections since this is from memory, and I'm not an astronomer, bad or otherwise.
My kids still love me. |
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Tokyodreamer
SFN Regular
USA
1447 Posts |
Posted - 01/31/2002 : 08:06:24 [Permalink]
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I thought it had to do with the refraction of light off the atmosphere. The angle of the light when the moon or the sun is on (or close to) the horizon makes it look bigger.
Could be wrong...
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Sum Ergo Cogito |
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Hook
Skeptic Friend
USA
79 Posts |
Posted - 01/31/2002 : 11:05:47 [Permalink]
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Hi, Megan.
Oh boy, a psychology question. 
This phenomenon has been studied for quite some time by Perception Psychologists and while there is no universal agreement on the details of the explanation, it is clearly a psychological phemonenon and not a physical one (i.e., refraction doesn't account for it). Hence, it is referred to as the "Moon Illusion." Here is a pretty good summary from Scientific American:
http://www.sciam.com/askexpert/astronomy/astronomy15.html
Hope this helps. :-)
"I don't care whether my neighbor believes in zero gods or 20 gods, I care whether my neighbor believes in democracy."
--Bill Moyers |
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Tokyodreamer
SFN Regular
USA
1447 Posts |
Posted - 01/31/2002 : 11:46:33 [Permalink]
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Thanks for setting us (or at least me!) straight, Hook. 
It seems this would actually be quite easy to test with a digital camera and some photo editing skills.
Just take a picture of the moon when it looks big and orange, then a picture when it is high in the sky.
Edit out all the extra stuff in the first picture with software, so that there are no objects in which to relate the moon's size.
The two pictures should show an identically sized moon, no?
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Sum Ergo Cogito |
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Garrette
SFN Regular
USA
562 Posts |
Posted - 01/31/2002 : 11:50:38 [Permalink]
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Thanks, Hook.
My kids still love me. |
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The Bad Astronomer
Skeptic Friend
137 Posts |
Posted - 01/31/2002 : 13:48:17 [Permalink]
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The rising/setting Moon and Sun look red for a similar reason as to why the sky is blue! See my webpage about it.
The Moon Illusion is actually fairly well understood now. I have a chapter in my upcoming book about it (hint hint) and I also have a page about that too.
*****
The Bad Astronomer
http://www.badastronomy.com
"With tremendous respect to [the] BA, the problem isn't getting scientists to talk, the problem can be getting them to shut up." |
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Zandermann
Skeptic Friend
USA
431 Posts |
Posted - 01/31/2002 : 17:08:31 [Permalink]
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In addition to the BA's pages, Megan (and TD -- this pretty well matches your suggestion), check out this Astronomy Picture of the Day from a few days ago.
Apparent size change is due to perception only.
"If in the last few years you haven't discarded a major opinion or acquired a new one, check your pulse. You may be dead." |
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ljbrs
SFN Regular
USA
842 Posts |
Posted - 01/31/2002 : 18:08:29 [Permalink]
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quote:
The rising/setting Moon and Sun look red for a similar reason as to why the sky is blue! See my webpage about it.
The Moon Illusion is actually fairly well understood now. I have a chapter in my upcoming book about it (hint hint) and I also have a page about that too.
*****
The Bad Astronomer
http://www.badastronomy.com
"With tremendous respect to [the] BA, the problem isn't getting scientists to talk, the problem can be getting them to shut up."
Amazon.com will take your orders for BA's book, but there is a wait (as I remember -- March of this year). Oh, well, it will get to me when it gets to me... Waiting is so, so, so difficult... The suspense is already getting to me.
ljbrs 
"Nothing is more damaging to a new truth than an old error." Goethe |
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Hook
Skeptic Friend
USA
79 Posts |
Posted - 01/31/2002 : 18:52:52 [Permalink]
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quote:
The rising/setting Moon and Sun look red for a similar reason as to why the sky is blue! See my webpage about it.
The Moon Illusion is actually fairly well understood now. I have a chapter in my upcoming book about it (hint hint) and I also have a page about that too.
*****
The Bad Astronomer
http://www.badastronomy.com
Hi, Phil. Ok, I'll admit that I somehow missed that you had a Moon Illusion page   . The Donald Simanek page you reference is excellent, but I couldn't remember where it was and was too busy at work to search. By the way, your note at the bottom implies the book by Trehub supports Simanek, when in fact Simanek's proposals are based in part on Trehub.
Can't wait for the book-- but guess I'll have to.
(P-)>
"I don't care whether my neighbor believes in zero gods or 20 gods, I care whether my neighbor believes in democracy."
--Bill Moyers |
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Garrette
SFN Regular
USA
562 Posts |
Posted - 02/01/2002 : 04:38:59 [Permalink]
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Thanks, Phil.
(That'll teach me to try my hand at things astronomical. Ah, well, there's always something for us to learn.)
My kids still love me. |
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Megan
Skeptic Friend
USA
163 Posts |
Posted - 02/02/2002 : 19:23:05 [Permalink]
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Thanks!!
~Megan~
"If in the last few years you haven't discarded a major opinion or acquired a new one, check your pulse. You may be dead." - Zandermann |
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Lisa
SFN Regular
USA
1223 Posts |
Posted - 02/03/2002 : 09:37:35 [Permalink]
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Hey Megan! I'm back in the good old USA! Rested and quite tan. Can't wait to get back and show off.
About the moon: remember what it looked like a couple of years ago during the forest fires? All the smoke gave it a reddish color. I'm not saying we should start tossing matches around the Black Hills, just that it looked kind of neat.
Lisa
(edited for silly typing)
If you're not living on the edge, you're taking up too much room.
Edited by - Lisa on 02/03/2002 09:38:45 |
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Chippewa
SFN Regular
USA
1496 Posts |
Posted - 02/05/2002 : 19:00:24 [Permalink]
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quote:
How come sometimes, when the moon is coming up, it is like huge?? And why does it look like an orange color??
In addition to the answers from the other folks here, the moon can also look kind of orange during a wonderful and rare even known as a lunar eclipse.
"Speaking without thinking like shooting without aiming." - Charlie Chan |
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The Bad Astronomer
Skeptic Friend
137 Posts |
Posted - 02/06/2002 : 10:49:17 [Permalink]
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quote:
the moon can also look kind of orange during a wonderful and rare even known as a lunar eclipse.
Ah, but that's the same reason it looks ornage when rising or setting. During a lunar eclipse, the sunlight hitting the Moon is passing through the thickest layers of the Earth's atmosphere. The blue, green and even yellow light is scattered away, leaving only orange and red to illuminate the Moon. Standing on the Moon, it would look to you as if the Sun were peeking around the circular shape of the Earth, just like at sunrise or sunset.
*****
The Bad Astronomer
http://www.badastronomy.com
"With tremendous respect to [the] BA, the problem isn't getting scientists to talk, the problem can be getting them to shut up." |
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Donnie B.
Skeptic Friend
417 Posts |
Posted - 02/06/2002 : 12:33:40 [Permalink]
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Hey... wouldn't it have been cool if they'd scheduled a lunar landing to coincide with a lunar eclipse (i.e. an Earth eclipse of the sun, from the lunar perspective)? They could have taken some truly unique photos, if it had worked out and they were "on the ground" at the time...
I know, I know, they wanted to land near the terminator for thermal control reasons, and during an eclipse that would have meant being right on the limb... but damn...
-- Donnie B.
Brian: "No, no! You have to think for yourselves!" Crowd: "Yes! We have to think for ourselves!" |
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