# Why does the moon look so big sometimes and smaller other times?

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Why does the moon look so big sometimes and smaller other times?

In: Physics

Context. If you actually measure it when it looks different sizes, you’ll see that it is the exact same size. The difference is that when it looks big, it is close to the horizon, where we can see it compared to things on the ground. We see the Moon behind everything, but still a significant size, this lets us know that it is big, so our mind adjusts how big we think it is. When it’s in the middle of the sky though, there’s nothing to compare it to, so you just see it for the size it is.

Plus the moons orbit isn’t a perfect circle, the same as our orbit around the sun. It can appear a full 14% bigger and 30% brighter.
[This might help](http://www.revimage.org/does-the-moon-orbit-earth-in-a-perfect-circle/)

Here’s a good way to test your own perception of that. Let’s say you’re going to go outside when the Moon is full; cover one eye; hold up a quarter so it covers the Moon; then move it in or out until it *just barely* covers.

Now how far will the quarter be from your eye?

Think this over. Write down your best estimate. Then wait for a full-moon night and try it out, and let’s see if you get a surprise.