What Do Rainbows Mean?

A rainbow is an optical illusion created when light strikes drops of water. The light is refracted, or changes directions, then is reflected by the back of the water drops. As this reflected light is leaving the water, it's refracted again at several angles [source: National Geographic].

You'd think we mortals would know everything about rainbows, as popular as they are. Yet there are actually quite a few myths out there about what a rainbow represents.

Think you're pretty rainbow-savvy? Here's betting you learn at least one new fact about them by the time you finish this article. Our first rainbow myth is probably the most famous.

In Irish folklore, rainbows symbolize good fortune. That's because leprechauns hide a pot of gold at the end of every one. Not only that, but that the pot of gold is guarded by a tricky leprechaun. The legend goes like this:

Once upon a time, the Vikings lived in Ireland, looting and plundering as they pleased, then burying their ill-gotten treasures all over the countryside. When they eventually departed from the Emerald Isle, they inadvertently left behind some of their booty, which the leprechauns found.

Now, the leprechauns knew the Vikings had gotten their treasures through stealing, which was wrong. This bad behavior made the leprechauns mistrust all people, Viking or not.

In order to ensure no humans could take what they now considered their gold, the leprechauns reburied it in pots deep underground all over the island. When rainbows appear, they always end at a spot where some leprechaun's pot of gold is buried [source: Mystical Myth].

Here's the catch: Believers who've searched for the legendary pot o' gold always end up stymied, because they can never find the rainbow's end (seriously, it's a matter of physics).

Rainbows have spiritual meaning for Jews and Christians. In the story of Noah's ark in the Book of Genesis, God shows Noah a rainbow and says, "Whenever the rainbow appears in the clouds, I will see it and remember the everlasting covenant between God and every living creature" (Genesis 9:16). The rainbow reminds Jews and Christians of God's promise to Noah to never again create an Earth-destroying flood.

In the Talmud, there is a blessing Jews can recite when beholding a rainbow: "Blessed art Thou, O Lord our God, King of the universe, Who remembers the covenant, is faithful to His Covenant, and keeps His word" (Berakhot 59a).

Since 1978, rainbows have become a universal symbol of pride for the LGBTQ+ community. Gilbert Baker, a gay man, artist and drag queen, designed the rainbow flag for the San Francisco Gay Freedom Day parade on June 25, 1978.

Baker's original design featured eight colors, each with a different meaning: hot pink for sex, red for life, orange for healing, yellow for sunlight, green for nature, turquoise for art, indigo for harmony and violet for spirit. To make it easier to mass-produce the rainbow flag, Baker later dropped hot pink and turquoise and replaced indigo with blue [source: Britannica].

The variety of pride flags has since seen incredible expansion to embrace a multitude of identities.

In Norse mythology, the Bifrost is a flaming rainbow bridge connecting Asgard, where the gods live, to Midgard, where humans live.

Under the rule of the god Odin, the all-seeing, all-hearing god Heimdall guarded the Bifrost.

In school you probably learned that the colors of the rainbow are (in order) red, orange, yellow, green, blue, indigo and violet. These are actually the colors of the visible spectrum.

Red has the longest wavelength and violet the shortest. (Some scientists think indigo is so similar to blue that it's indistinguishable for most people [source: National Geographic].) But those seven hues are not the only ones in the world, of course. Where's the pink, for example? Or brown? Or sage, aqua, celadon and coral?

Those colors, and more, are actually there in the rainbow. They're just invisible.

Rainbows contain upward of 1 million colors — that's right, 1 million — in a much larger continuum than the seven measly ones with which we're familiar [source: Howard]. Unfortunately, our human peepers can't see all of those other hues. So does this mean rainbows contain them or not? That's for you to debate.

Rainbows can multiply. Double, tertiary (triple) and quaternary (quadruple) rainbows all can occur.

Double rainbows occur when light gets reflected twice inside water droplets. When this happens, the second rainbow appears above the main one and is fainter. Its colors are also reversed (red is on the inner section and violet on the outer arch) due to the second reflection [source: National Geographic].

A tertiary rainbow occurs when light is reflected a third time. But you have to be facing the sun to see one because the sun is its center. Tertiary rainbows are very difficult to notice partly because you're looking into the sun, and partly because they're quite faint and very broad.

Even harder to see are quaternary rainbows, which form when light is reflected a fourth time. You also need to be facing the sun to spot these, and they're even fainter than tertiary rainbows [source: National Geographic].

And it doesn't stop there: Scientists have detected a 200th order rainbow (that's a rainbow with light reflected 200 times) in the lab [source: National Geographic].