How far can I see on a clear day? - Big Questions (Ep. 18)

Hi, I'm Craig and I have eyes like a hawk with human eyes

And this is Mentalfloss on YouTube. Today I'm going to answer Brian Curry's big question

On a clear day, how many miles can I see in every direction? How about on a hazy day

Well, Brian, the answer to your question really depends on circumstances. Like some nights you can look up with the sky and see the Andromeda Galaxy

which is a full 2.5 million light years away. But you probably want more information than that

So that's what you're going to get. Maybe you don't want more, but we like to talk about stuff at you

So we're going to do that. Let's get started. According to a study done in 1942, the human eye can actually see a single flame burning 30 miles away

That's around 50 kilometers, but that could only happen if the Earth were flat

You're a thing flat. We can actually see much further than we do see. It's that darn horizon that gets in the way

The horizon, by the way, is where the Earth meets the sky. You've heard of it. You've seen it

On Instagram. Since that's the case, you've probably already figured out that the altitude has an impact on how far you can see

So, if you're an average height of 5 foot 7 inches and standing on the ground, the horizon is approximately 2.9 miles away

So people can see 2 miles away boom done No unfortunately it not that simple Humans can come up with a simple formula that works for every situation and that because we have things like atmospheric refraction which is how light passes through

different mediums in different ways. Thanks to that, things like air pressure and temperature are actually affecting the way you see the horizon

Also that big guy at the top of the Sears Tower when you're trying to look out the window, but you just won't get out of the way

You pay 20 bucks to get up there. Then of course, as Brian so astutely mentioned, there are factors like haziness and fog

If you wanted to see really far, you could hop on a plane or climb Mount Everest, but then you would probably be

have a cloud get in your way. All of that said, Dr. Andrew T. Young

Mr. T, of San Diego State University, has developed this formula that takes

refraction into consideration. All you got to do is insert your eye level in feet

and it will give you an approximation of your distance to the horizon in miles. But

like I said, no formula you find for this will be perfect. There are just too many variables. If all this confusing refraction stuff is too much for you, you can just

calculate how many miles there are between you and the horizon. There's a link in the doodoo to an online calculator that will doobly do the work for you

PUNS. Thanks for watching Mental Floss on YouTube made by these lovely people

If you have a question of your own, leave it in the comments. See you next week from an average distance