Why Does the Moon Look Bigger? Moon Illusion Explained and Proven

Gazing into the night sky and being shocked at how large the moon looks has had people baffled for years. There has been no mention of a supermoon, so it is not that. So why depose the moon look bigger tonight?

We often believe the moon is much larger when it is lower in the sky to the unaided eye. However, when its hight in the sky, we may think it is much smaller in size.

What you are witnessing is what is called a “Moon illusion.”

A moon illusion is an optical illusion caused by your brain; tricked into believing the moon looks much larger than when the moon is lower in the night sky. Over the years, this illusion has been much debated how it happens but is accepted; it is an illusion that is happening.

Okay, so we now know that our brain is tricking us into believing that the moon looks larger despite its not. Also, we know it is much departed by scientists how the optical illusion happens.

One study suggests that as humans, we are not very good at judging vertical distances. With this, we believe the moon is smaller and further away from us as we perceive the night sky as a flattened dome when it is, in fact, a sphere.

Other studies point out that we use objects like houses on the foreground and background horizon to judge a distance. However, as we have no reference point in the night sky like on the horizon or brain gives us the optical illusion.

The picture below shows how, or brain believes the moon in the night sky looks vs. how the moon in the night sky looks in reality.

Moon illusion vs Reality

How to prove the moon illusion

We believe that there is a thing called a moon illusion, and our brain is doing this to us. Is there any way to prove it that we can carry out at home?

Yes, there are many different ways to prove a moon illusion and break thought this illusion; the best way is to use the “dime trick.”

Get a US dime or a UK 5 pence; both coins are around 18mm, so perfect for this test.

Hold out the coin at arm’s length and use it to cover the moon when it is both low and high on the horizon.

You will see that there is no appreciable difference in the moon’s size when it is low or high on the horizon.

How to prove the moon illusion demonstration

If you don’t have a dime or 5 pence to hand, your little pinky finger is around the same size. So holding your arm out and using your pinky finger should achieve the same results.

Is there a time when the moon is bigger?

Yes, when a supermoon happens, the moon is more extensive than it is at any other time. The moon can be up to 30 percent larger when a super moon occurs. However, much more significant this may sound in reality, it is to the untrained eye unnoticeable.


That brings us to the end of my article about why the moon looks bigger on any given night.

Its all down to our brain, giving us an optical illusion that we can overcome with the “dime trick.”

Only a few times, the moon is more significant than other times; however, most people will be unable to tell the difference in the size.

Moongazing has fascinated people for years, and research is continuously undertaken on our nearest neighbor. I have compiled a complete lunar 100 guide to help stargazers enjoy the moon in a more in-depth way.