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uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged. |
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#1
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Now I don't know about anyone else, but the so-called 'super moon' didn't
look any bigger than loads of other moon rises I've witnessed. The full-moon at moonrise often appears much bigger (and so does the sun at sunrise). OK, so it's also supposed to be closer to us in its orbit to boot, but I reckon that extra closeness is not THAT close that you're going to be able to visually notice the difference. Eye-catcing it was... but no more eye-catching than many another moonrise at full moon. Regards... David Allan. |
#2
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In article ,
David Allan writes: Now I don't know about anyone else, but the so-called 'super moon' didn't look any bigger than loads of other moon rises I've witnessed. The full-moon at moonrise often appears much bigger (and so does the sun at sunrise). OK, so it's also supposed to be closer to us in its orbit to boot, but I reckon that extra closeness is not THAT close that you're going to be able to visually notice the difference. Eye-catcing it was... but no more eye-catching than many another moonrise at full moon. To me, it did seem noticeably larger and brighter than normal. That was fifteen minutes ago, when it was already well away from the horizon. Of course it could have been a psychological effect, since I knew that it was supposed to be "super". -- John Hall "The covers of this book are too far apart." Ambrose Bierce (1842-1914) |
#3
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Definitely looks bigger here; commented on this to other half last night
too. |
#4
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On 19/03/2011 19:45, John Hall wrote:
In , David writes: Now I don't know about anyone else, but the so-called 'super moon' didn't look any bigger than loads of other moon rises I've witnessed. The full-moon at moonrise often appears much bigger (and so does the sun at sunrise). OK, so it's also supposed to be closer to us in its orbit to boot, but I reckon that extra closeness is not THAT close that you're going to be able to visually notice the difference. Eye-catcing it was... but no more eye-catching than many another moonrise at full moon. To me, it did seem noticeably larger and brighter than normal. That was fifteen minutes ago, when it was already well away from the horizon. Of course it could have been a psychological effect, since I knew that it was supposed to be "super". There are both real and psychological effects. The moon's orbit is distinctly elliptical, so the moon's distance varies significantly as it goes round. This can be shown by looking at solar eclipses, which vary from the moon being large enough to completely cover the sun for about 7 minutes at any given point, to "annular" eclipses when even at mid-eclipse a ring of sunlight is left around the moon's disk. Of course, the moon passes through "perigee" every month, but it is only really noticeable when it occurs at full moon and our satellite is displayed in full sunlit glory. The shape of the moon's orbit also varies slightly due to gravitational effects from the changing geometry of earth, moon and sun. This has resulted in the orbit currently becoming slightly more elliptical than normal, hence the slightly closer approach highlighted for tonight. The earth's orbit and angle of the rotation axis also change in this way over long timescales - these variations affect the distribution of solar heating over the globe and a gentleman called Milankovitch showed how, together with "feedback" effects, these variations could partly explain the pattern of ice ages and interglacials. The very real psychological effect is that the brain uses various cues to estimate the size of objects very far away. Experiments with pairs of drawings have shown that the brain can be "fooled" by a surprising amount - an object seen close to the horizon providing a "scale" for it seems larger than one high in the sky. And there have been any number of incidents which demonstrate beyond all reasonable doubt that people will believe almost any old tosh - and judge what they see and hear on this basis - if they do not know or cannot understand the truth. -- - Yokel - Yokel posts via a spam-trap account which is not read. |
#5
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On Mar 19, 10:12*pm, Yokel wrote:
There are both real and psychological effects. The moon's orbit is distinctly elliptical, so the moon's distance varies significantly as it goes round. *This can be shown by looking at solar eclipses, which vary from the moon being large enough to completely cover the sun for about 7 minutes at any given point, to "annular" eclipses when even at mid-eclipse a ring of sunlight is left around the moon's disk. *Of course, the moon passes through "perigee" every month, but it is only really noticeable when it occurs at full moon and our satellite is displayed in full sunlit glory. The shape of the moon's orbit also varies slightly due to gravitational effects from the changing geometry of earth, moon and sun. *This has resulted in the orbit currently becoming slightly more elliptical than normal, hence the slightly closer approach highlighted for tonight. *The earth's orbit and angle of the rotation axis also change in this way over long timescales - these variations affect the distribution of solar heating over the globe and a gentleman called Milankovitch showed how, together with "feedback" effects, these variations could partly explain the pattern of ice ages and interglacials. The very real psychological effect is that the brain uses various cues to estimate the size of objects very far away. *Experiments with pairs of drawings have shown that the brain can be "fooled" by a surprising amount *- an object seen close to the horizon providing a "scale" for it seems larger than one high in the sky. *And there have been any number of incidents which demonstrate beyond all reasonable doubt that people will believe almost any old tosh - and judge what they see and hear on this basis - if they do not know or cannot understand the truth. -- - Yokel - Yokel posts via a spam-trap account which is not read. The moon is always closer to the earth than average at new moon and full moon, slightly more so in the latter case, so the closest perigees always occur near full moon. This current one is nothing very special - the moon was closer in 1992, 1993 and 2008 by a few tens of km. I have never been able to look at the moon and discern whether it is at apogee or perigee even though the size varies by ±7%. The altitude illusion easily swamps any such change. The moon is actually measurably *larger* when high in the sky compared with when on the horizon by a maximum of about 1.6% in these latitudes because you are then closer to it by a large fraction of the earth's radius, which is about 1/60th of the distance to the moon. This full moon, although bright because of the closeness, is not especially so, the moon being 5.00 degrees from the ecliptic (near the maximum) and the increase in brightness at full phase is surprisingly large due to the direct reflection effect. Tudor Hughes, Warlingham, Surrey. |
#6
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On Mar 20, 4:56*am, Tudor Hughes wrote:
On Mar 19, 10:12*pm, Yokel wrote: There are both real and psychological effects. The moon's orbit is distinctly elliptical, so the moon's distance varies significantly as it goes round. *This can be shown by looking at solar eclipses, which vary from the moon being large enough to completely cover the sun for about 7 minutes at any given point, to "annular" eclipses when even at mid-eclipse a ring of sunlight is left around the moon's disk. *Of course, the moon passes through "perigee" every month, but it is only really noticeable when it occurs at full moon and our satellite is displayed in full sunlit glory. The shape of the moon's orbit also varies slightly due to gravitational effects from the changing geometry of earth, moon and sun. *This has resulted in the orbit currently becoming slightly more elliptical than normal, hence the slightly closer approach highlighted for tonight. *The earth's orbit and angle of the rotation axis also change in this way over long timescales - these variations affect the distribution of solar heating over the globe and a gentleman called Milankovitch showed how, together with "feedback" effects, these variations could partly explain the pattern of ice ages and interglacials. The very real psychological effect is that the brain uses various cues to estimate the size of objects very far away. *Experiments with pairs of drawings have shown that the brain can be "fooled" by a surprising amount *- an object seen close to the horizon providing a "scale" for it seems larger than one high in the sky. *And there have been any number of incidents which demonstrate beyond all reasonable doubt that people will believe almost any old tosh - and judge what they see and hear on this basis - if they do not know or cannot understand the truth. -- - Yokel - Yokel posts via a spam-trap account which is not read. * * The moon is always closer to the earth than average at new moon and full moon, slightly more so in the latter case, so the closest perigees always occur near full moon. *This current one is nothing very special - the moon was closer in 1992, 1993 and 2008 by a few tens of km. *I have never been able to look at the moon and discern whether it is at apogee or perigee even though the size varies by ±7%. *The altitude illusion easily swamps any such change. *The moon is actually measurably *larger* when high in the sky compared with when on the horizon by a maximum of about 1.6% in these latitudes because you are then closer to it by a large fraction of the earth's radius, which is about 1/60th of the distance to the moon. * * *This full moon, although bright because of the closeness, is not especially so, the moon being 5.00 degrees from the ecliptic (near the maximum) and the increase in brightness at full phase is surprisingly large due to the direct reflection effect. Tudor Hughes, Warlingham, Surrey.- Hide quoted text - - Show quoted text - Thanks both of you. Interesting. we had a veil of high cloud at 9pm when I looked, so the size was hard to judge. There was a spectacular halo though. |
#7
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On 19/03/2011 19:29, David Allan wrote:
Now I don't know about anyone else, but the so-called 'super moon' didn't look any bigger than loads of other moon rises I've witnessed. The full-moon at moonrise often appears much bigger (and so does the sun at sunrise). OK, so it's also supposed to be closer to us in its orbit to boot, but I reckon that extra closeness is not THAT close that you're going to be able to visually notice the difference. Eye-catcing it was... but no more eye-catching than many another moonrise at full moon. If you were measuring it or trying to take a photo with a decent large lens then the difference would be obvious. The orbital eccentricity is about 0.05 so the moons apparent diameter last night at perigee was 10% bigger than it would be if it occurred at the furthest point apogee. That you cannot easily spot the difference by eye says a lot about the limitations of the claim that seeing is believing. Once you have a camera, micrometer or other measuring instrument the change is obvious. Regards, Martin Brown |
#8
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![]() "Tudor Hughes" wrote in message ... On Mar 19, 10:12 pm, Yokel wrote: The moon is always closer to the earth than average at new moon and full moon, slightly more so in the latter case, (snip) Tudor Hughes, Warlingham, Surrey. .......................... Tudor I assume you mean that the average earth-moon distance at new and (especially) full moons is greater than the overall average, but do you have chapter and verse for this? I am not challenging the statement, but I had never heard it before and I am curious. Regards, Roger |
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