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Why Does the Moon Look Larger at the Horizon? We Asked a NASA Scientist: Episode 50


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Preparations for Next Moonwalk Simulations Underway (and Underwater)

We’ve been talking about this for 2,000 years. Aristotle mentions it. And in our own time, scientists are designing experiments to figure out exactly what’s going on. But there’s no consensus yet.

Here’s what we do know.

The atmosphere isn’t magnifying the Moon. If anything, atmospheric refraction squashes it a little bit. And the Moon’s not closer to us at the horizon. It’s about 1.5 percent farther away. Also, it isn’t just the Moon. Constellations look huge on the horizon, too.

One popular idea is that this is a variation on the Ponzo illusion. Everything in our experience seems to shrink as it recedes toward the horizon — I mean clouds and planes and cars and ships. But the Moon doesn’t do that. So our minds make up a story to reconcile this inconsistency. Somehow the Moon gets bigger when it’s at the horizon. That’s one popular hypothesis, but there are others. And we’re still waiting for the experiment that will convince everyone that we understand this.

So why does the Moon look larger on the horizon? We don’t really know, but scientists are still trying to figure it out.

[END VIDEO TRANSCRIPT]

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      This video offers a close-up look at a small portion of the magnificent Rosette Nebula, as photographed by the Hubble Space Telescope. Though Hubble cannot take three-dimensional pictures, this video is a visualization treatment of the photo to give a sense of depth with foregrou…




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      Details
      Last Updated Apr 23, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Contact Media Claire Andreoli
      NASA’s Goddard Space Flight Center
      Greenbelt, Maryland
      claire.andreoli@nasa.gov
      Ray Villard
      Space Telescope Science Institute
      Baltimore, Maryland
      Related Terms
      Hubble Space Telescope Astrophysics Astrophysics Division Galaxies Goddard Space Flight Center Mars Nebulae Planetary Nebulae Planetary Science Planets Spiral Galaxies Stars The Solar System The Universe
      Additional Links
      Hubble’s 35th Anniversary page
      NASA Ciencia: Con la mirada en el infinito: La NASA celebra 35 años de la puesta en órbita del telescopio Hubble
      ESA Hubble’s Story


      Keep Exploring Discover More Topics From Hubble
      Hubble Space Telescope


      Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.


      Hubble Science Highlights



      Hubble’s 35th Anniversary



      Hubble Images


      View the full article
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