# What did people think rainbows were, pre-Newton? **URL:** \ **Category:** Factual Questions\ **Created:** [February 18, 2006, 5:28pm UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101 "2006-02-18T17:28:27Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![DarrenS](https://avatars.discourse-cdn.com/v4/letter/d/977dab/32.png) [@DarrenS](https://boards.straightdope.com/u/DarrenS)\ **Post date:** [February 18, 2006, 5:28pm UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101/1 "2006-02-18T17:28:27Z")
Before Newton did his prism thang, I’m guessing people had noticed that you could produce pwetty colors by passing light through various lenses and prisms. But they must have been awed to see this huge, multi-colored _thing_ in the sky when it was sunny + raining. So, before Newton’s explanations, what was the common thinking on what rainbows were? Did people have an inkling that white light was composed of all colors? ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [February 18, 2006, 5:37pm UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101/2 "2006-02-18T17:37:33Z")
I wouldn’t say an _inkling_ so much, more of a _glimmer_. The real key to progress was recombining the light to produce white light, IMHO. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [February 18, 2006, 6:06pm UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101/3 "2006-02-18T18:06:55Z")
> [@DarrenS](#): > > So, before Newton’s explanations, what was the common thinking on what rainbows were? Genesis 9: > [@](#): > > 12 And God said, This is the token of the covenant which I make between me and you and every living creature that is with you, for perpetual generations: > > 13 I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth. > > 14 And it shall come to pass, when I bring a cloud over the earth, that the bow shall be seen in the cloud: > > 15 And I will remember my covenant, which is between me and you and every living creature of all flesh; and the waters shall no more become a flood to destroy all flesh. > > 16 And the bow shall be in the cloud; and I will look upon it, that I may remember the everlasting covenant between God and every living creature of all flesh that is upon the earth. > > 17 And God said unto Noah, This is the token of the covenant, which I have established between me and all flesh that is upon the earth. I’m pretty sure that was the most commonly-held theory, at least in the (sigh) Judeo-Christian world. ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [February 18, 2006, 6:14pm UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101/4 "2006-02-18T18:14:47Z")
The theoretical study of rainbows actually goes back [quite far:](http://physicsweb.org/articles/review/15/11/1/1) > [@](#): > > “Caustics are the brightest places in an optical field. They are the singularities of geometrical optics. The most familiar caustic is the rainbow, a grossly distorted image of the Sun in the form of a giant arc in the skyspace of directions, formed by the angular focusing of sunlight that has been twice refracted and once reflected in raindrops.” > > This explanation of the rainbow, given by Descartes in 1637, was both a pioneering exercise of computational theoretical physics and the culmination of several millennia of what Raymond Lee and Alastair Fraser call “the slow and convoluted evolution of physical reasoning about the rainbow”. > > We learn, for example, how Aristotle - in about 350 BC - understood the rainbow as redirected sunlight, but misunderstood the redirection as mirror reflection from clouds. We learn how Qutb al-Din in Persia and Theodoric in Freiberg, in about 1300, understood the importance of reflection and refraction within individual raindrops but were unable to explain why the light is concentrated near the rainbow angle. > > Equally “slow and convoluted” was our understanding of a rainbow’s colours, which culminated (at least at the level of ray optics) with Newton’s incorporation of the spectral dispersion of water into Descartes’ theory. ---
**Author:** ![DarrenS](https://avatars.discourse-cdn.com/v4/letter/d/977dab/32.png) [@DarrenS](https://boards.straightdope.com/u/DarrenS)\ **Post date:** [February 18, 2006, 6:53pm UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101/5 "2006-02-18T18:53:26Z")
Thanks: very informative answers. I’m surprised by how close the previous guesses actually were. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [February 18, 2006, 7:54pm UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101/6 "2006-02-18T19:54:42Z")
> [@DarrenS](#): > > Thanks: very informative answers. I’m surprised by how close the previous guesses actually were. The work on refraction, interference, and diffraction pretty much established the wave theory and buried Newton’s ideas about the corpuscular nature of light. Then along came Max Planck, _et al._ ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [February 18, 2006, 8:56pm UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101/7 "2006-02-18T20:56:29Z")
You can see what Wikipedia has to say on the [history of the science of rainbows](http://en.wikipedia.org/wiki/Rainbow#History_of_the_science_of_rainbows), although it’s pretty much the same as **Kimstu** ’s info. If you’re interested, you can scroll down and have a look at what it says on “Rainbows in religion and mythology,” but I don’t know whether such things were believed literally or whether they were taken as poetic or whimsical. Also, some of these things, such as the Bible passage **Alessan** quoted, give different kinds of answers to the “What is a rainbow?” question from the answer Newton gave. (Kind of like the question “What is a traffic light?” could be answered either “It’s a device made of light bulbs and switches” or “It’s a signal to tell cars when to stop and go.”) ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [February 18, 2006, 10:56pm UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101/8 "2006-02-18T22:56:29Z")
I remember reading in a _Scientific American_ article many years ago that even in the late 1800s most Americans still believed rainbows were divine phenomena. What lay people think and what Scientists think are usually quite different in all ages. ---
**Author:** ![DfrntBreign](https://avatars.discourse-cdn.com/v4/letter/d/f6c823/32.png) [@DfrntBreign](https://boards.straightdope.com/u/DfrntBreign)\ **Post date:** [February 19, 2006, 12:39am UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101/9 "2006-02-19T00:39:21Z")
> [@ftg](#): > > I remember reading in a _Scientific American_ article many years ago that even in the late 1800s most Americans still believed rainbows were divine phenomena. > > What lay people think and what Scientists think are usually quite different in all ages. A lot of people still think rainbows are divine. Oh so very, very divine! 🙂 (I’m sorry, just too easy.) ---
**Author:** ![Anaamika](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@Anaamika](https://boards.straightdope.com/u/Anaamika)\ **Post date:** [February 19, 2006, 12:50am UTC](https://boards.straightdope.com/t/what-did-people-think-rainbows-were-pre-newton/345101/10 "2006-02-19T00:50:53Z")
> [@Alessan](#): > > Genesis 9: > > I’m pretty sure that was the most commonly-held theory, at least in the (sigh) Judeo-Christian world. Does anyone have any idea about the \*non \*Judeo-Christian world? Wonder what they thought. China was pretty advanced, think they had any idea? What about Persia?