Why Does the Moon Look Larger at the Horizon? We Asked a NASA Expert

Summary

The video explores the mystery of why the Moon appears larger on the horizon. Despite centuries of observation, scientists still don't have a clear answer. Common theories suggest it could be due to the Ponzo illusion, where distant objects seem smaller, and our brains mistakenly make the Moon appear larger to reconcile this inconsistency. The atmosphere does not magnify the Moon, and it is not closer to the Earth when near the horizon. Researchers are still conducting experiments to solve this phenomenon, but there is no consensus yet on the true cause.

Takeaways

• 😀 The Moon appears larger on the horizon, but scientists still don't fully understand why.
• 😀 The phenomenon has been discussed for over 2,000 years, with Aristotle being one of the earliest to mention it.
• 😀 Despite extensive research, there is no consensus on the exact cause of the Moon's larger appearance.
• 😀 Atmospheric refraction does not make the Moon appear larger; in fact, it slightly squashes it.
• 😀 The Moon is not closer to the horizon; it's actually about 1.5% farther away at that point.
• 😀 The size perception is not unique to the Moon; constellations also appear larger on the horizon.
• 😀 One hypothesis suggests the effect is related to the Ponzo illusion, where objects appear smaller as they recede.
• 😀 The brain may 'fill in the gaps' to reconcile the inconsistency between our expectations and the Moon's appearance.
• 😀 There are multiple theories about the effect, but none have been proven universally accepted yet.
• 😀 NASA and scientists continue to experiment and try to pinpoint the cause of the Moon’s horizon illusion.

Q & A

Why does the Moon appear larger at the horizon?

The exact reason why the Moon looks larger at the horizon is still not fully understood. While various theories exist, no consensus has been reached among scientists.

Has the reason for the Moon's size at the horizon been figured out?

No, scientists have been studying this phenomenon for over 2,000 years, but they still don't have a definitive explanation. There are several hypotheses, but none have been proven to everyone’s satisfaction.

Does the atmosphere magnify the Moon at the horizon?

No, the atmosphere doesn't magnify the Moon. In fact, atmospheric refraction tends to squash the Moon a little, making it appear slightly smaller rather than larger.

Is the Moon closer to Earth when it is near the horizon?

No, the Moon is actually about 1.5 percent farther away when it appears near the horizon compared to when it’s higher in the sky.

Are other celestial objects, like constellations, affected the same way as the Moon?

Yes, constellations also appear larger on the horizon, much like the Moon. This suggests a common perceptual phenomenon that affects how we view distant objects near the horizon.

What is the Ponzo illusion, and how is it related to the Moon's appearance?

The Ponzo illusion is a visual illusion that makes objects appear larger or smaller depending on the background. Some scientists believe that the apparent enlargement of the Moon on the horizon could be a variation of this illusion.

Why do objects seem to shrink as they move toward the horizon?

In our everyday experience, objects like clouds, planes, cars, and ships appear to shrink as they move away from us and towards the horizon, which leads to a natural assumption that the Moon should behave in the same way.

Why does the Moon appear larger if it’s not actually closer?

Since the Moon doesn’t behave like other objects by shrinking as it recedes, our minds try to reconcile this inconsistency by perceiving it as larger when it is near the horizon.

Is the current scientific consensus about the cause of the Moon’s appearance at the horizon clear?

No, there is no clear consensus on the cause of the Moon's appearance at the horizon. While some theories like the Ponzo illusion are popular, experiments are still being conducted to figure out the exact reason.

What is the ongoing scientific approach to understanding the Moon's size at the horizon?

Scientists are still conducting experiments to understand this phenomenon. However, despite various theories, there is no one experiment that has convinced everyone yet.