# Thread: Year's Biggest Full Moon Friday Night

1. Have been feeling down so was unable to check it out. Nick did say that it was cloudy here last night and that he didn't get to see it either.

When I was in my science class and the subject was the planets and such, I fell in love. Not only is the view awesome and breathtaking but also it makes me see how small I am in this universe. It was so interesting and still is to learn and see the things surrounding us. Thank you jHope for posting and sharing with us.

Raven

2. Originally Posted by Wise Young
...I believe that it is because the earth's atmosphere has a magnifying effect on the moon when it is close to the horizon. My friend, a physicist, thinks that it is all relative and just a perceptual trick that my brain is playing.

Wise.
I can see the argument you are considering Wise. When objects are on the horizon, we can look thru something like 100 miles of denser atmosphere, which is made up of moisture. When it's high overhead, we're looking through only 10 - 20 miles of atmosphere (actually goes higher, but 50% of the atmosphere is below 18,000 feet).

So you would think that the extra moisture would cause the magnifying effect much like how a spoon looks bigger in a glass of water.

I think the pencil eraser trick should answer the question though. If the thicker atmosphere near the horizon does magnify the moon, then the eraser should appear smaller at arms length. When the moon nears high up in the sky, the eraser should appear bigger.

Think I'm gunna try that out!

3. Originally Posted by Rrrrronnn
I can see the argument you are considering Wise. When objects are on the horizon, we can look thru something like 100 miles of denser atmosphere, which is made up of moisture. When it's high overhead, we're looking through only 10 - 20 miles of atmosphere (actually goes higher, but 50% of the atmosphere is below 18,000 feet).

So you would think that the extra moisture would cause the magnifying effect much like how a spoon looks bigger in a glass of water.

I think the pencil eraser trick should answer the question though. If the thicker atmosphere near the horizon does magnify the moon, then the eraser should appear smaller at arms length. When the moon nears high up in the sky, the eraser should appear bigger.

Think I'm gunna try that out!
Rrrrrron, there is certainly a lot of debate on the subject.
http://www.straightdope.com/columns/...ar-the-horizon

Here was my reasoning...

When the moon is close to the horizon, the light from the bottom of the moon is hitting the atmosphere at a greater angle close to horizon, than the top. When this happens, the light is refracted more, like all lenses, as shown in the attached:

I don't know. if we consider the atmosphere a magnifying glass, in the same way that convex lens in the above picture is a magnifying glass. Light coming from an object that hits the earth directly at 90% to the atmosphere surface will not be refracted at all. However, light coming in closer to the lens edge will be refracted so that it focuses to a point.

One would imagine that this problem would have been definitively measured and solved by now. By the way, it would be far more accurate just taking your digital camera and taking a picture of the moon when it is on the horizon and when it is up in the sky.

Wise.

4. Not related as such but, Leonardo da Vinci found painting ways to cheat on perspective projection (quite interesting); Link.

5. Originally Posted by Wise Young
Rrrrrron, there is certainly a lot of debate on the subject.
http://www.straightdope.com/columns/...ar-the-horizon

Here was my reasoning...

When the moon is close to the horizon, the light from the bottom of the moon is hitting the atmosphere at a greater angle close to horizon, than the top. When this happens, the light is refracted more, like all lenses, as shown in the attached:

I don't know. if we consider the atmosphere a magnifying glass, in the same way that convex lens in the above picture is a magnifying glass. Light coming from an object that hits the earth directly at 90% to the atmosphere surface will not be refracted at all. However, light coming in closer to the lens edge will be refracted so that it focuses to a point.

One would imagine that this problem would have been definitively measured and solved by now. By the way, it would be far more accurate just taking your digital camera and taking a picture of the moon when it is on the horizon and when it is up in the sky.

Wise.
Dr. Wise, I think I am going to have to side with your physicist colleague. I would side with you if the sun was warmest at sunrise and sunset and not at its hottest during the summer when it is directly overhead.

6. Originally Posted by Tufelhunden
Dr. Wise, I think I am going to have to side with your physicist colleague. I would side with you if the sun was warmest at sunrise and sunset and not at its hottest during the summer when it is directly overhead.
LOL, sigh. Intensity of sun-rays is related to how much atmosphere they pass through before getting to you. When the sun is directly overhead, it passes through a lot less atmosphere. Wise.

7. Originally Posted by Wise Young
LOL, sigh. Intensity of sun-rays is related to how much atmosphere they pass through before getting to you. When the sun is directly overhead, it passes through a lot less atmosphere. Wise.
Good point, lol.

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