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Post by HeadLikeARock (was postbaguk) on Jul 31, 2007 19:07:22 GMT -4
Driving in the north-east of England last night after dusk (near the coast), was confronted with the fantastic sight of a blood-red full-moon rising over the north sea. A few minutes later it was amber. A few minutes later, one of my favourite songs, Whole of the Moon by The Waterboys came on the radio, exactly as the moon came out from behind a tree, this time in its usual colour as the sky darkened and it rose in the sky.
Quite stunning.
Never seen this atmospheric effect before, was wondering if anyone knows how rare it is?
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Post by Ginnie on Jul 31, 2007 20:38:04 GMT -4
A few minutes later, one of my favourite songs, WHole of the Moon by The Waterboys came on the radio, exactly as the moon came out from behind a tree, I was at a Neil Young concert once in Barrie, Northern (to some) Ontario, Canada. During his performance of the song 'Helpless' which has the lyrics " There is a town in north ontario...Yellow moon on the rise". a huge yellow moon close to the horizon was visible on the right side of the stage.
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Post by BertL on Jul 31, 2007 20:55:30 GMT -4
I can recall seeing a huge yellow moon close to the horizon on one occasion too, when I was five. I've always wondered what it is. That is, if something like it would be brought up. It's the only time in my life I've seen it, and I'm not entirely sure what could explain it.
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Post by donnieb on Jul 31, 2007 22:05:33 GMT -4
Yellow, orange, and red Moons are caused by the same atmospheric phenomenon that produces colorful sunsets and sunrises. You're looking through much more atmosphere toward the horizon than when looking overhead. The air itself can produce some color, for the same reason the sky is blue (preferential scattering of the short wavelengths by nitrogen and water vapor). Also, the amount of dust in the air (which greatly magnifies the scattering) varies greatly, and accounts for the day-to-day differences in the amount of coloration.
Or were you asking about the illusion that the Moon looks very large on the horizon compared to overhead? That's been explained as well. It is an illusion -- if you measure the Moon carefully there's no actual size difference. It looks bigger on the horizon because of a psychological effect. It's hard to explain without pictures, but basically our brains interpret the sky overhead as being "closer" than the horizon. Therefore an object that's the same objective size looks bigger on the horizon than overhead; we interpret it as being farther away. I guess it all goes back to our distant ancestors -- the sky is "just above the treetops", but the horizon is "miles and miles away".
Coincidentally, I saw a blood-red sunrise the other day. Quite dramatic. It preceded several days of stormy weather, confirming the old saying:
Red sky at night, sailor's delight. Red sky at dawning, sailors take warning.
You need to say it in a New England accent to make the internal rhyme work (dawning/wahning).
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Post by HeadLikeARock (was postbaguk) on Aug 1, 2007 1:47:24 GMT -4
Yellow, orange, and red Moons are caused by the same atmospheric phenomenon that produces colorful sunsets and sunrises. You're looking through much more atmosphere toward the horizon than when looking overhead. The air itself can produce some color, for the same reason the sky is blue (preferential scattering of the short wavelengths by nitrogen and water vapor). Also, the amount of dust in the air (which greatly magnifies the scattering) varies greatly, and accounts for the day-to-day differences in the amount of coloration. Or were you asking about the illusion that the Moon looks very large on the horizon compared to overhead? That's been explained as well. It is an illusion -- if you measure the Moon carefully there's no actual size difference. It looks bigger on the horizon because of a psychological effect. It's hard to explain without pictures, but basically our brains interpret the sky overhead as being "closer" than the horizon. Therefore an object that's the same objective size looks bigger on the horizon than overhead; we interpret it as being farther away. I guess it all goes back to our distant ancestors -- the sky is "just above the treetops", but the horizon is "miles and miles away". The illusion of the moon appearing to be larger near the horizon was very noticeable. The main point of the question was, how often does something like the colour change occur? Red to orange to yellow in the space of about 15/20 minutes. It's not something I remember previously. I guess the 4 conditions required are a rising moon, a full moon, at or around sunset, with decent visibility. Here's a photo I just Googled up which is very similar - www.pikespeakphoto.com/images/sunmoon/moon_rising.jpg
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Post by Trinitrotoluene on Aug 1, 2007 19:11:53 GMT -4
Hey Postbag! Long time no see buddy I think the time the colour change takes to occur would be dependent on the speed the moon rises above the horizon, as you are viewing it through less and less atmosphere as it rises the colour changes from a noticeable red, to orange, to yellow and then to white.
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Post by HeadLikeARock (was postbaguk) on Aug 1, 2007 19:29:50 GMT -4
Hey Postbag! Long time no see buddy I think the time the colour change takes to occur would be dependent on the speed the moon rises above the horizon, as you are viewing it through less and less atmosphere as it rises the colour changes from a noticeable red, to orange, to yellow and then to white. Now then Gav. I'm trying to find out how often this effect occurs, as I don't remember seeing it myself. I don't think it's as rare as I first thought, but will probably be a while before I see the next one!
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Post by Kiwi on Aug 3, 2007 9:00:01 GMT -4
On 1 December 1975 I caught an overnight ferry from Lyttleton, near Christchurch, to Wellington and before going to bed went up on deck to look at the view. There was a bright red glow out near the eastern sea horizon that scared the hell out of me for a while -- the cold war was still full on and I had always been terrified as a young kid at the thought of the Soviets blowing us up with an atomic bomb. Maybe they'd had a trial run, disposing of our Chatham Islands. Luckily I soon saw the red limb of the moon appear and was very relieved to see it -- it was two nights after full moon. I was 26 at the time and had never seen or heard of that bright red glow, but I don't recall ever seeing the moon rise over the sea on any other occasion. As soon as it was fully above the horizon it started reverting to its usual orange then yellow colours.
I live on the west coast and earlier this year when comet McNaught was here I watched the moon through binoculars as it set over the sea, and the last portion of the limb that was visible was only a dark orange. I've seen many other moon-sets, but never a red one.
As already mentioned it depends on atmospheric conditions. With very little land around we have very clear air in New Zealand, but back about 1991 when Mount Pinatubo in the Philippines blew its top our sky was so polluted that it was possible to view the sun in binoculars as it set. I remember marvelling at the sunspots that were clearly visible.
One other phenomenon that's said to be extremely rare is the green flash as the sun disappears below the horizon, but soon after learning of it I saw it on three out of four consecutive nights, and the third was too cloudy to see the sun. I've seen it about eight times altogether. Some green flashes are very faint, but I've seen about three bright emerald-green ones.
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Post by HeadLikeARock (was postbaguk) on Aug 6, 2007 18:23:07 GMT -4
Nice story Kiwi.
For any UK based members who are interested, it may be possible to see this again later this month. Sunset and moonrise are at exactly the same time on Tuesday 28th August - 19:58. Subsequent nights should provide good viewing too, with the time of moonrise increasing by approx 15 minutes each night, and sunset occuring a couple of minutes earlier.
When I saw this on 31 July, sunset was 20:53 and moonrise 21:22, about 1/2 an hour later.
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