Can You Reach The End of a Rainbow?

The end of the rainbow may be the best place to raid a leprechaun stash, but it proves a strangely difficult destination to reach. Christian explains why you can’t get there, and why there really isn’t even a a “there” there.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,
Christian Seger here. Okay, so you have this amazing idea
to start your own business, a licorice themed food truck.
You got liquorice Ravioli, licorice gumbo. It's genius, right, But
the bank turned you down and your Kickstarter campaign failed

(00:23):
the fund. Fortunately, you know where you might be able
to find a large stash of gold if you can
only get to the end of this rainbow you've been
following for six hours. But wait a minute, is it
actually possible to get to the end of a rainbow?
And if so, what will you find when you get there?
Let's start with the bad news. Sorry, everyone, lepre cons

(00:45):
are liars. You cannot reach the end of the rainbow.
If you were to mark on a map the place
where the rainbow seems to meet the land, and then
travel to that location, you would not be standing inside
a glorious pillar of colors. There would be nothing there
except probably the fresh smell of a recent rain shower.

(01:05):
To understand why this is, we need to look at
how rainbows form. Rainbows are created when sunlight reflects and
refracts through water droplets suspended in the air on the
opposite side of you from the sun. Those water droplets
act like both a mirror and a prism. Like a mirror,
they reflect the sunlight back towards you, but like a prism,

(01:28):
they also bend and disperse the light. This is because
rays of light shining through the air change speed when
they enter a different medium, for example water. This sudden
change in speed bends the trajectory of the light and
disperses white light into the whole roy g BIV spectrum.
The reason you see a nice ordered gradient of colors

(01:52):
within a rainbow, going from red to violet is because
this refraction bends each of the different colors of light
at a slightly different angles. So, for example, red light
bends at forty two degrees, violet light bends at forty degrees,
and all the other colors are somewhere in between. So
all right, let's find a rainbow. To do this, you

(02:14):
need to locate your anti solar point. That your anti
solar point is really just the point in space that's
a d eighty degrees or exactly opposite from the sun.
A simple way to find this is to go outside
and look for the shadow of your own head. Now
imagine drawing a straight line in three dimensions from the
sun through your head to the shadow of your head.

(02:37):
Now look up. If there is a rainbow to be seen,
you will find it by facing away from the sun
and looking for an arc forty two degrees above that
line from the sun to your anti solar point. Notice
that the apparent location of your rainbow depends on three things.
Where the sun is, where the water droplets are, and

(02:58):
where your eyes are. Change any one of those variables
and you'll see a different rainbow or none at all.
So no matter where you see your rainbow, if you
try to walk out to meet it, you'll be changing
the variable of your own position, and you could be
walking forever, or at least until your rainbow disappears. Trying
to find the end of a rainbow is sort of

(03:20):
like trying to walk to the end of your own shadow.
Somebody else could stand at the apparent end of your rainbow,
but you will never ever reach this location yourself. But
here's another thing. A rainbow isn't actually a bow. Rainbows
are circular. Usually, when you're standing on the ground, most
of the rainbow is blocked by the horizon. In rare cases,

(03:42):
like if you're in an airplane or something, you'll actually
be able to see the entire rainbow as a round,
spectacular beauty. But there's an obvious takeaway from this. It
doesn't actually meet the ground anywhere. There's just the altitude
where you can't see it anymore. Despite all this science
that is quite well understood, you're going to find plenty

(04:04):
of people on the Internet swearing up and down that
they have found the end of a rainbow. And look,
I don't know what to tell you. I'm not sure
what's up with that. Check out the brain stuff channel
on YouTube, and for more on this and thousands of
other topics, visit how stuff works dot com.