Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,
Speaker 1: Christian Seger here. Okay, so you have this amazing idea
Speaker 1: to start your own business, a licorice themed food truck.
Speaker 1: You got liquorice Ravioli, licorice gumbo. It's genius, right, But
Speaker 1: the bank turned you down and your Kickstarter campaign failed
Speaker 1: the fund. Fortunately, you know where you might be able
Speaker 1: to find a large stash of gold if you can
Speaker 1: only get to the end of this rainbow you've been
Speaker 1: following for six hours. But wait a minute, is it
Speaker 1: actually possible to get to the end of a rainbow?
Speaker 1: And if so, what will you find when you get there?
Speaker 1: Let's start with the bad news. Sorry, everyone, lepre cons
Speaker 1: are liars. You cannot reach the end of the rainbow.
Speaker 1: If you were to mark on a map the place
Speaker 1: where the rainbow seems to meet the land, and then
Speaker 1: travel to that location, you would not be standing inside
Speaker 1: a glorious pillar of colors. There would be nothing there
Speaker 1: except probably the fresh smell of a recent rain shower.
Speaker 1: To understand why this is, we need to look at
Speaker 1: how rainbows form. Rainbows are created when sunlight reflects and
Speaker 1: refracts through water droplets suspended in the air on the
Speaker 1: opposite side of you from the sun. Those water droplets
Speaker 1: act like both a mirror and a prism. Like a mirror,
Speaker 1: they reflect the sunlight back towards you, but like a prism,
Speaker 1: they also bend and disperse the light. This is because
Speaker 1: rays of light shining through the air change speed when
Speaker 1: they enter a different medium, for example water. This sudden
Speaker 1: change in speed bends the trajectory of the light and
Speaker 1: disperses white light into the whole roy g BIV spectrum.
Speaker 1: The reason you see a nice ordered gradient of colors
Speaker 1: within a rainbow, going from red to violet is because
Speaker 1: this refraction bends each of the different colors of light
Speaker 1: at a slightly different angles. So, for example, red light
Speaker 1: bends at forty two degrees, violet light bends at forty degrees,
Speaker 1: and all the other colors are somewhere in between. So
Speaker 1: all right, let's find a rainbow. To do this, you
Speaker 1: need to locate your anti solar point. That your anti
Speaker 1: solar point is really just the point in space that's
Speaker 1: a d eighty degrees or exactly opposite from the sun.
Speaker 1: A simple way to find this is to go outside
Speaker 1: and look for the shadow of your own head. Now
Speaker 1: imagine drawing a straight line in three dimensions from the
Speaker 1: sun through your head to the shadow of your head.
Speaker 1: Now look up. If there is a rainbow to be seen,
Speaker 1: you will find it by facing away from the sun
Speaker 1: and looking for an arc forty two degrees above that
Speaker 1: line from the sun to your anti solar point. Notice
Speaker 1: that the apparent location of your rainbow depends on three things.
Speaker 1: Where the sun is, where the water droplets are, and
Speaker 1: where your eyes are. Change any one of those variables
Speaker 1: and you'll see a different rainbow or none at all.
Speaker 1: So no matter where you see your rainbow, if you
Speaker 1: try to walk out to meet it, you'll be changing
Speaker 1: the variable of your own position, and you could be
Speaker 1: walking forever, or at least until your rainbow disappears. Trying
Speaker 1: to find the end of a rainbow is sort of
Speaker 1: like trying to walk to the end of your own shadow.
Speaker 1: Somebody else could stand at the apparent end of your rainbow,
Speaker 1: but you will never ever reach this location yourself. But
Speaker 1: here's another thing. A rainbow isn't actually a bow. Rainbows
Speaker 1: are circular. Usually, when you're standing on the ground, most
Speaker 1: of the rainbow is blocked by the horizon. In rare cases,
Speaker 1: like if you're in an airplane or something, you'll actually
Speaker 1: be able to see the entire rainbow as a round,
Speaker 1: spectacular beauty. But there's an obvious takeaway from this. It
Speaker 1: doesn't actually meet the ground anywhere. There's just the altitude
Speaker 1: where you can't see it anymore. Despite all this science
Speaker 1: that is quite well understood, you're going to find plenty
Speaker 1: of people on the Internet swearing up and down that
Speaker 1: they have found the end of a rainbow. And look,
Speaker 1: I don't know what to tell you. I'm not sure
Speaker 1: what's up with that. Check out the brain stuff channel
Speaker 1: on YouTube, and for more on this and thousands of
Speaker 1: other topics, visit how stuff works dot com.