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Discussion Starter #1
in reading a book I came across the word gibbous in reference to the moon. I looked it up because I didn't know what that meant. It is an almost full moon with a flattened edge, like dropping something round and soft to the floor. Tonight we have a gibbous moon and I can't figure out how it works. The shadow of the earth will produce crescents , waxing and waning and a half moon is fine but how do you get a gibbous moon which looks like a Sunday duff that's hit the deck?
Would really like to know.
 

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Haven't you just answered your own question?

It seems that the word "gibbous" is from the Latin "gibbus", meaning "hump" and is applied when ever the moon is seen as larger than a crescent and less than a full circle; and therefore applies during most of the lunar cycle.

Thank you for prompting me to look it up! I had never heard the word used - or certainly not in conversation on any bridge - either! I'm sure that others will be able to tell us more.
 

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Discussion Starter #3
Thanks Barry but I am mystified that you say I have answered my own question. The earth is the only source of shadow on the moon(?) so how can you get a dropped duff effect. The earths shadow must leave a concave or convex shadow on the moon. Not sure about the perfect half moon now actually. ??
 

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Discussion Starter #4
Thanks Barry but I am mystified that you say I have answered my own question. The earth is the only source of shadow on the moon(?) so how can you get a dropped duff effect. The earths shadow must leave a concave or convex shadow on the moon. Not sure about the perfect half moon now actually. ??
P.S. Dropped Duff effect sounds better than gibbous. Can I claim it for my own the way doctors hanker to have a disease named after them ?
 

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Thanks Barry but I am mystified that you say I have answered my own question. The earth is the only source of shadow on the moon(?) so how can you get a dropped duff effect. The earths shadow must leave a concave or convex shadow on the moon. Not sure about the perfect half moon now actually. ??
I really am astonished at your concept of the Earth 's Umbra and Penumbra causing a shadow on the Moon , thereby causing concave or convex etc. shapes of the Moon .

You really should study the Lunar orbit. From that you will realise when there is no Moon to see, you are looking at the back of the Moon. As the Moon continues through it's orbit , so more of the surface is sunlit.


Get , say, a tennis ball and shine a torch behind it. Then move the ball around you and you will see it has nothing to do with your shadow.


ATB


Laurie.
 

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Discussion Starter #6
What?If I shine a torch on a tennis ball I will get a half illumination every time.Please explain.
 

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Rather leave the ball and torch set up and move yourself around the ball. Perhaps more algebraicaly related to the relative motion than intuitive but the it should produce the same visual sequence without getting a terpschordial hernia?
 

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You should try without moving your legs just as much as without the lips, E-S. Anyway if you have problems down below I am sure we can truss you to sort them out.
 

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Haven't you just answered your own question?


Thank you for prompting me to look it up! I had never heard the word used - or certainly not in conversation on any bridge - either! I'm sure that others will be able to tell us more.
I can't believe that Barrie. Basic Second Mates (FG) stuff!
 

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#10

Thank you, Ian!

You are quite right. But other than in an examination syllabus or other professional matters (now more than fifty years ago) I never did hear the word "gibbous" used in conversation and had long since forgotten its meaning!

In almost thirty years in pilotage, I don't recall hearing the word "gibbous" used in practice, at all!
 

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My good lady, a retired midwife, is enquiring if gibbous could be used to describe a lady in an advanced state of pregnancy.
 

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#10

On further thought I would add that it was customary to observe (if at all), in my own experience, the moon either to be waxing or else "on the wane" - and more informative, too.

Readily do I admit my ignorance of many things - but this might explain my ignorance of the term "gibbous" - if I ever really knew it!
 

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"The Opera hat, also known as the Gibus, after its inventor, is a type of top hat which is collapsible. The opera hat was invented in 1812 by a Frenchman called Antoine Gibus."

I used to own one, I wore it down the pub at certain Phases of the moon. Is any confusion creeping in? :>}
 

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#15

Now, this is becoming serious!

Well do I remember a Laurel & Hardy sketch where Stan is trying to teach Olly some manners - by not pouring too-hot tea into a saucer to drink.

"No," says Stan, "That is not the way to do it. Do not blow on it, but fan it, instead, with your Opera hat."
 

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#15

Now, this is becoming serious!

Well do I remember a Laurel & Hardy sketch where Stan is trying to teach Olly some manners - by not pouring too-hot tea into a saucer to drink.

"No," says Stan, "That is not the way to do it. Do not blow on it, but fan it, instead, with your Opera hat."
Sign of a true gentleman.
 

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Discussion Starter #18
Yes entertaining and humourous as your responses have been gents but please explain the flat bit on a gibbous moon. I will remind you that the moon is visible at night only because of the sun . So where does the flat bit come from? Kind regards to the bridge.
 

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#19

Granty,

You would probably have better answers if you could explain your question more clearly.

To the best of my knowledge and belief, the only time when any aspect of the moon is commonly seen as flat is at half-moon, which you indicate that you understand, by virtue of every schoolboy's appreciation of the changing view of the moon at every phase from new moon to full moon. It has already been pointed out that this is basic stuff which every mariner should know.

Or are you merely extracting urine?

Or are you telling us that you have seen the moon with a flat edge visible horizontally (which might very well look like a Christmas pudding on a plate)? That would be the only other interpretation of your question. Do please let us have a more detailed explanation of what you have seen. And what were the weather condtions and cloud formation at the time?
 
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