IF you love optical illusions you may be pleased to hear there’s a natural illusion visible in the sky most evenings.
It’s called the Moon Illusion and it’s been baffling humans since ancient times.
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Sometimes the Moon appears very large early in the evening and seems to get smaller as it moves higher in the sky.
This isn’t anything to do with its distance from us and when you see the Moon, it remains the same size for the whole evening.
It’s just your brain creating an optical illusion and tricking you into thinking it looks smaller.
It should be noted that the Moon does move closer and further away from Earth on a cycle but its size in the sky during one evening does not physically change.
A video from AsapSCIENCE explains how, in reality, the Moon is the exact same size when it appears on the horizon as it will be when it’s high in the sky.
There are many theories surrounding why this is, but the main theory is that when the Moon is low on the horizon it can be compared to many earthly things.
Objects like buildings and trees can make the Moon seem huge when it’s lower in the sky.
However, the vast sky makes the Moon seem small because there is nothing to compare it to.
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So, once the Moon reaches its highest point, it looks smaller than when it first started rising.
This is similar to an effect known as the Ebbinghaus Illusion, which shows how objects of the same size can look bigger or smaller depending on what they are surrounded by.
According to the Moon Illusion theory, if you bend over and look through your legs at the full Moon rising, it won’t seem as big because the objects surrounding it will no longer register as familiar because you’re upside down.
Does the Moon change shape?
The Moon doesn’t change shape and doesn’t produce any light – how we see it is due to the brightness from the Sun reflecting on it.
Nasa explains: “The shape of the Moon isn’t changing throughout the month. However, our view of the Moon does change.
“The Moon does not produce its own light. There is only one source of light in our solar system, and that is the Sun.
“Without the Sun, our Moon would be completely dark.
“What you may have heard referred to as ‘moonlight’ is actually just sunlight reflecting off of the Moon’s surface.”
A Full Moon is seen every 29.5 days.
On occasion, the Moon can look larger than usual due to where it is in its orbit.
What is a Supermoon?
A Supermoon is a combination of two different astronomical effects.
It’s when a new or full Moon coincides with a perigee – the Moon’s closest point to Earth in its monthly orbit.
A Moon has to come within 90% of its closest approach to Earth to be formally defined as a Supermoon.
That means the Moon needs to come within 224,865 miles of Earth and be a Full Moon.
