See a Huge Moon Illusion Wednesday

Love looking at the moon! Moon River… wider than a mile… What if there was no moon? How different we would be!

See a Huge Moon Illusion Wednesday

Robert Roy Britt
Senior Science Writer
Tue Jun 17, 11:15 AM ET

As the full moon rises this Wednesday evening, June 18, many people will be tricked into thinking it's unusually large


The moon illusion, as it's known, is a trick in our minds that makes the moon seem bigger when it's near the horizon. The effect is most pronounced at full moon. Many people swear it's real, suggesting that perhaps Earth's atmosphere magnifies the moon.

But it really is all in our minds. The moon is not bigger at the horizon than when overhead.

The illusion will be particularly noticeable at this "solstice moon," coming just two days before summer starts in the Northern Hemisphere. The reason, according to NASA, lies in lunar mechanics: The sun and full moon are like kids on a see-saw; when one is high, the other is low. This week's high solstice sun gives us a low, horizon-hugging moon and a strong, long-lasting version of the illusion.

If it's any consolation, space station astronauts report the same effect.

Here's how it works: Your mind believes things on the horizon are farther away than things overhead, because you are used to seeing clouds just a few miles above, but the clouds on the horizon can indeed be hundreds of miles away. So if we think something (such as the moon) is farther away, and it's not, then it seems larger.

If you remain doubtful, test the idea yourself. Go out at moonrise with a small object, perhaps a pencil eraser. Hold it at arm's length as the moon rises and compare the sizes of the moon and the eraser, then repeat the experiment an hour or two later when the moon is high in the sky. A rolled up tube of paper works well, too.

Moonrise times vary by location. On Wednesday, it will come up at these local times at these locations, according to NASA: New York City, 8:58 p.m.; Miami, 8:35 p.m.; Seattle, 9:51 p.m.

The moon rises about 50 minutes earlier Tuesday night, when the effect will also be noticeable because the moon will be nearly full. Oh, and that raises another fallacy: There's no such thing as a full moon.

Additional moonrise times for your location are available from the U.S. Naval Observatory Web site.

Visit and explore our huge collection of Space Pictures, Space Videos, Space Image of the Day, Hot Topics, Top 10s, Multimedia, Trivia, Voting and Amazing Images. Follow the latest developments in the search for life in our universe in our SETI: Search for Life section. Join the community, sign up for our free daily email newsletter, listen to our Podcasts, check out our RSS feeds and other Reader Favorites today!

Read and post comments | Send to a friend


About mikeymikez

Interested in music, film, good books and Korean culture.
This entry was posted in Uncategorized and tagged , . Bookmark the permalink.

7 Responses to See a Huge Moon Illusion Wednesday

  1. Simple says:

    Moon moves so fast. I was piling up all my law books for my camera. so that it will stay still. the minute i piled up 2 books, it moves higher, so i kept piling and piling. at the end, i used up all my law books yet couldn't get a good pic. it was so funny though. so i decided to use my hands and hold it still. hahahaha.. so much works for piling up books yet end up using hands only.

  2. I wonder if I'll see it on the way to work!..if the skies are clear tonight. ^-^ I've never noticed the moon looking larger and I wonder what it'll look like!

  3. Mikey says:

    Ah, the law book technique! ^^ Now you have an alternative to that…That does sound funny!! Good for your technique experience though! πŸ˜›

  4. Mikey says:

    HUGE! lol Hope you got to see it tonight! It was huge for our BBQ this evening!! I took some pix, but didn't have my big zoom and tripod. I got some BBQ pix and even a mini-movie though!! πŸ˜› I'll post some when I get home tonight. I had a telescope when we lived in Hawaii, and that was so cool, looking at the southern constellations you can't see from the mainland, like the Southern Cross!

  5. I don't know it looked sort of large…but I feel like I've seen it larger before but that's probably just my way off judgment fooling me! πŸ˜› Ah a BBQ sounds like fun! My brother loves to do that every time he visits…funny the only time I eat meat is when he's here! I should buy a telescope so that I could see those and I wasn't aware that there are stars which are only visible from here? Really?

  6. Mikey says:

    It was just the alignment of things that would make the moon appear larger to people. MB isn't so easily fooled! :PI love BBQ over a charcoal flame!! John does great BBQ cooking and we get the best stuff we can find, carnivore style! ^^Have you been to a luau where they cook the pig with hot rocks all day underground? Sounds awesome!A telescope is pretty cool. You might want to find a astronomy group in your area and check it out. It's the best and fastest way to learn! Seeing the moon's face close up or the rings of Saturn is unforgettable!! πŸ™‚ More correctly, I should have said that there are constellations you can't see from the mainland because it is too far north. San Diego is like 33 degrees North, while Hawaii is about 23 degrees.I'll have to send you that song by CSN called Southern Cross…I have been around the world,
    Lookin' for that woman, girl,
    Who knows love can endure,
    And you know it will (and you know it will)
    When you see the Southern Cross for the first time,
    You understand now why you came this way,
    'Cause the truth you might be runnin' from is so small,
    But it's as big as the promise, the promise of a coming day.
    So I'm sailing for tomorrow, my dreams are a-dyin',
    And my love is an anchor tied to you, tied with a silver chain.
    I have my ship and all her flags are a-flyin'.
    She is all that I have left and music is her name.

  7. I've been to a luau like that a long time ago but I'm not really fond of pork so I stay away now! πŸ˜› Interesting that Hawaii is such an ideal place to view the stars and every thing else out there…if I see a telescope that's not too expensive I think I'll buy one and that'll give me more reasons to be outdoors on a clear night…I'm kind of a indoor homebody these days. πŸ˜›

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s