Why the moon looks very large at the time of rising ??

Question

Ever noticed that the moon appears to be very large at the time of rising, and appears to be considerably small, when it is at 45 degrees, so my question is why is that so ?? when the observer is equi-distant to the moon at all times..

Answer 1

It's not just about the moon being on the horizon, that's why you don't see it when so much the moon sets on the sea or over a mountain range.

To get the eye to see the illusion in a really stunning way, you need something in the foreground which adds a perspective effect.

I have only seen this effect twice and trust me, when you do you'll be amazed! Both times I was on a short rise of a hill and the moon was rising (or setting) over the end of the road. It really does look huge! Try to find somewhere that fits the conditions.


The same effect also happens with the sun.

The reference gives a way of faking/reprodiucing the illusion with a piece of round paper.
Good luck in seeing it,

Answer 2

it doesn't. It's an optical illusion. If you were to look at the moon when it is at it's highest point in the sky. you will have nothing to compare it to.
Try this little experiment..
Hold a ruler in your hand at arms length. Point it at the moon and measure it through one eye. Then wait till the next night when the moon comes up again and do the same thing while the moon is low on the horizon. You will find them the same. The only thing is there are buildings and other objects to compare it to when it is low in the horizon.
Hope that helps

Answer 3

When the moon is high in the sky, we have nothing to compare it with. When it is near or on the horizon we compare it with known objects such as trees or buildings. This gives rise to the illusion that the moon is bigger when on the horizon. It is all to do with how our brains interpret visual information.

If you take an instrument such as a theodolite or a sextant and measure the width of the moon in degrees, it is the same at all angles of elevation.

Answer 4

actually, the atmospheric angle has nothing to do with it, and its not actually magnified. its an optical illusion having to do with orientation and proximity to the horizon. only some people see it, actually, the moon always looks constant to me. you can overcome this illusion, however, by looking at the moon upside down, since this inverts the horizon.

EDIT (So that people will stop writing me and trying to tell me how to see the moon's optical illusion): i REALLY meant what i said. Even when others report that the moon looks HUGE, i've never seen the optical illusion myself. It might have to do with how heavily involved i used to be with art, such that perspective shift isn't difficult for me at all (i also happen to be able to read books upside down). truth of the matter is, i just don't see it, even when everyone around me does and sending me a message isn't going to make me see it either.

Answer 5

It is called the Moon Illusion. There is a lot of research about it over the years, and a book called "The Moon Illusion". There are more theories about it than there are people who have studied it.

Answer 6

Hi. If you look through a paper towel tube, say, the size would appear the same. It's when you see the moon against, say, a distant steeple or mountain then your mind sees it as larger.

Answer 7

You have it right - it APPEARS larger. In fact, you are unconsciously comparing it with known objects (the horizon, that tree, the house, etc).

When it's up in the sky, there's nothing to compare it to!

I agree, it DOES look a lot bigger

Answer 8

Its an optical illusion.. Its because its close to the horizon... you have scale.. when its high in the sky u have nothing to compare its size too.

Answer 9

Like a convex lens, the earth's atmosphere acts like a magnifier lens.

Answer 10

To much wine not enough weed.