What causes the Moon illusion, where it appears so large when setting or rising? This psychological trick is known as the Moon illusion and occurs due to how our brains interpret visual signals. Photographs demonstrate that while the Moon does appear large close to horizon, its size does not match up with what we perceive with our eyes – an illusion caused by thousands of years of observation but which still has no scientific explanation.
At night, when the moon is at its full, you can go outside and find a spot to watch it rise. It’s an awe-inspiring sight that usually draws an exhilarating “Wow!” from all who witness it – whether peering over distant mountains rising from the sea, soaring over urban landscapes or hanging over forests.
Here’s the thing: it all lies within yourself. That illusionary size of the moon could just be an illusion created by our environment or other physical factors – something you can test yourself with ease through various methods.
How to be certain you’re not being deceived by the Moon illusion
Place your outstretched index finger in front of the Moon and you’ll notice that its size is nearly identical to your fingernail. Take a closer look by passing your hand through a tube of paper or bending your body and looking backward between your legs; these steps will make it clear that the Moon is much smaller than previously believed.
A more reliable method for estimating the size of an image of the Moon is taking a photograph when it’s near the horizon and then when in the sky. If your camera’s zoom settings remain unchanged, you should see that the Moon appears roughly the same size both sides (although slightly distorted towards horizontal in closer to Horizon due to atmospheric interference with weak optical lenses).
Photographers can create the illusion of the Moon illusion with photographs taken at low points on the horizon with long lenses that include mountains, buildings or trees in the frame. Keep this in mind the next time you come across stunning images showing a massive Moon over landscape: these were made by zooming into distant objects close to earth so that it appears bigger in those pictures due to being zoomed into perspective.
The Moon will appear more yellow as it approaches the horizon.
When the Moon is lower in the sky, its hue can differ dramatically. Generally, it takes on an orange or yellow hue rather than its usual blue-tinged glow when high up in the atmosphere. This occurs because light traveling farther through atmosphere is scattered and replaced by longer wavelengths which appear redder (dust or pollution may also contribute).
What causes us to see an illusion of the moon?
Be prepared: we don’t really know. That said, depending on your perspective it could either be disappointing or an opportunity for wonderment at our brains which remain mysterious. Despite centuries of observation, scientists still can’t provide a scientifically sound explanation.
The proposed explanations are linked to two fundamental aspects of our perception of the world: how far away objects appear when closer or farther away; and how far we imagine they will be when near the edge of horizon. Unfortunately, our brains often forget that distance between Earth and Moon does not vary much no matter its position in the sky at any given night.
Some speculate that objects in the foreground of your lunar view could play a role. Could mountains, trees, and buildings help fool your brain into believing the Moon is closer and larger than it actually is? Around a century ago, the Ponzo illusion was first described. This trick involves two intersecting lines that look like railroad tracks stretching off in the distance. Between them are two horizontal bars of equal length that appear to have different dimensions due to your brain’s hard-wired sense of distance – due to how forced perspective is often used in paintings.
However, this explanation may not be the most plausible one. NASA astronauts in orbit observe an illusion of the moon but lack any foreground objects to serve as distance indicators. Therefore, something else must be going on here.
Perhaps you can just take it easy?
Even if there isn’t an exhaustive explanation of why we perceive things this way, a huge Moon still makes for an impressive sight. While we may never fully comprehend why our minds work this way, taking a moment to be amazed by its enormity will provide us with lasting memories. Until further explanations come into focus, let us enjoy being awestruck by this magnificent object while it lasts.
(Source NASA)
