Why, when the moon first rises and is low in the sky, does it appear much bigger that when it high in the sky?

Answer 1

Because of density... the atmostphere acts as a MAGNIFYING GLASS...

Answer 2

I am not an expert in the field by any means but had the same question a few months ago posed to me by a friend of mine. What I found is that it is nothing more than an optical illusion. When it is low or near the horizon, other objects, like buildings trees, hills, and the curve of the Earth are also in our field of vision and seem dwarfed by our massive satellite, thus producing confusion in our minds allowing us to interpret it as a larger object than it actually is. If you wish to test out the optical illusion hypothesis, take a ruler, or a set of calipers, or even an unfolded paper clip. Hold it, at a full arms length, up to the moon when it looks enormous while it is low in the sky and record the size, for instance on the ruler, in inches. Wait a few hours until it is high in the sky and measure it again, also holding the ruler at a full arms length (for consistency), you will find that the size has not changed.
Pretty weird, but that's the optical illusion we all experience.

Answer 3

It is commonly believed that some sort of magnification occurs when the moon is close to the horizon. This is not true.

One of the most popular theories for this phenomenon was put forth by Mario Ponzo - he said that the mind judges an object's size on the basis of it's foreground or background. Low lying trees and houses which appear smaller than the moon at moonrise or moonset therefore cause this illusion. However, a big problem with this theory is that even airline pilots, with no references to judge the size of the moon against, encounter the illusion.

Another theory postulates that the brain perceives the sky as a flattened dome rather than the true hemisphere it really is. The theory runs that we believe things immediately overhead, flying birds for example, are closer than birds on the horizon. When the moon is on the horizon, the brain therefore miscalculates its true size and distance.

For more on alternative explanations and the illusion itself, see
http://en.wikipedia.org/wiki/Moon_illusion

Answer 4

It has to do with reference points. It's actually always the same size. It just looks bigger next to the trees that it does way in the middle of the sky next to nothing. Next time you are out at night hold your arm extended in front of your body and move your thumb to cover the moon. Your thumb will be a good reference point no matter where the moon is in the sky.

Answer 5

Its more a matter of how close it is to Earth during its orbit

Incidentally it can appear to be large and high in the sky too.

Answer 6

It is an illusion. People tend to perceive objects on the horizon as larger than they really are, but you can destroy the illusion by looking at the horizon upside down. Really! I have tried it. And it is not only the Moon, but trees and buildings too. As you tilt your head more and more things on the horizon start to look smaller. I notice that sideways is enough tilt for me to see things on the horizon as noticeable smaller than when looking upright. The usual suggestion is to bend over and look at the horizon between your legs, but that is just to embarrassing for me so I tilt my head sideways until I am looking upside down to one side of my legs and notice the size changing when I am about half Way to being upside down. Try it, it is easy!

Answer 7

Because you have something to directly compare it to (the earth) rather than just being out there alone in the sky.

Answer 8

It is an optical illusion!
When it is low, we compare with other Earth objects, mountain, buildings, etc., and seems incredible larger, while, when it is high, it seems smaller, compared to the skies!

Answer 9

it's the same size, it's an optical illusion.