
Your Brain Can’t Handle the Moon - pmcpinto
http://nautil.us/issue/24/error/your-brain-cant-handle-the-moon-rp
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calinet6
I always thought it was a very simple relative size illusion. When placed next
to objects on the horizon that provide a relative measuring stick of size, we
perceive the moon as large in comparison. When the moon is high and we instead
have a vast and large sky free of landmarks to use as subconscious or
conscious measuring sticks, it appears comparatively small.

There is a lot of cognitive function in-between, sure, but I never thought it
was so complicated.

~~~
JoeAltmaier
But that's complicated enough! Our brains use ad-hoc algorithms even for
simple things like relative size. Look at relative brightness - there are
endless optical illusions where a patch of dark and a patch of light are
actually exactly the same tone.

Context is everything to our brains/vision system. Its alarming how warped our
perception is.

~~~
alanfalcon
It would be alarming if our perception was not warped—contextual awareness is
far more useful than absolute perception in non-specialized situations (like
most survival tasks).

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saalweachter
This website seems to republish articles periodically:
[http://nautil.us/issue/19/illusions/your-brain-cant-
handle-t...](http://nautil.us/issue/19/illusions/your-brain-cant-handle-the-
moon)

The older article was on HN as well:
[https://news.ycombinator.com/item?id=8635384](https://news.ycombinator.com/item?id=8635384)

That seems kind of skeevy of nautil.us. [EDIT: Although, to their credit, they
do say at the veeeeery bottom they originally published it 2014.]

~~~
jessriedel
What's skeevy about it?

~~~
saalweachter
I'm not sure, I keep flip-flopping on it.

On the one hand, I can see how it'd be useful to new readers to resurface good
old content, but it's also irksome to old readers. It's annoying to pick up a
new magazine and have read the articles before, or a new book by a favorite
author and discover that it's just the first half of an older, larger novel,
or a short story collection and find that the stories have all been published
before. You've wasted your time, money, and now you have nothing to do on your
six hour flight.

I suspect the largest problem is that I've spent too much time around SEO
people, so whenever I see anything slightly unexpected with how content is
surface, I can just hear them in my head, saying things like, "And then three
weeks from now, we'll 403 redirect the old URL to the new URL, doubling our
google link-juice."

There's nothing necessarily _wrong_ with republishing old content, it just
strikes me as ... skeevy.

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gadders
What surprised me about the moon was when I read that its diameter is less
than the width of Australia. I just imagined it to be bigger than that.

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finnjohnsen2
My brain can't handle the kind of pop-ups that article throws in my face.

~~~
copsarebastards
Adblock+, bro.

~~~
finnjohnsen2
I've got adblock, but it doesn't stop that popup for some reason.

~~~
WorldWideWayne
Same here. So, I had to use Quick Javascript Switcher to turn off Javascript
for this site because running your Javascript on my machine is a _privilege_ ,
not a right.

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wmt
For me the illusion isn't really the Moon illusion but the sky illusion. Sky
on top of me feels closer to me than the horizon, even though I know it isn't,
so it's not that surprising that the same angular size near the horizon feels
bigger than on top of me.

------
rilita
After the first couple of paragraphs my own analysis is this:

1\. Distance in the mind is based on cues; 3d binocular cues only work at
distances less than a mile or so. Beyond that your mind depends on relative
reasoning to know 3d structures. A moon close to the ground will connect to
the ground you see and be placed at the furthest possible distance. Anything
at that distance is made to feel larger in the mind.

2\. If you look at a moon up in the sky, there are no cues to indicate how far
away it is or anything.

3\. A moon up in the sky is surrounded by empty space. Lots of empty space
will conceptually "crowd out" the moon and make it appear smaller not larger.

I then finished reading the article. Conclusion of researchers: #1. Good joy
guys? ...

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CarVac
You still have depth perception with one eye...you get parallax from head
movements. When viewing photos you don't get any parallax.

I wonder if there could be experiments using VR to measure this effect?

~~~
rimunroe
People have made head tracking systems by mounting the sensor bar from a Wii
on the brim of a baseball cap, and then placing the Wiimote on the top of
their screen. I saw a video of someone playing Half Life 2 with it, and it
looked to be surprisingly effective. Also, the difference between the Oculus
Rift DK1 (which does not have positional head tracking) and the DK2 (which
does have it) is pretty incredible. Obviously, the type of virtual environment
you're dealing with has a huge effect on how strong the illusion is.

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ezequiel-garzon
The moon illusion is the most intriguing illusion I know. I'm sure it can be
replicated with experiments and such, but the primacy of our nearby neighbor
makes it special. When a friend of mine told me about I was convinced it had
to do with an atmospheric phenomenon, and that taking pictures would verify
this. And then I looked it up... more than puzzling!

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jkot
Moon is bigger closer to horizon, thanks to refraction.

~~~
onion2k
If that were the case then it'd be bigger in photographs. It isn't.

~~~
jkot
Well it is a few arc seconds, but it is bigger :-)

