Why does a rainbow have 7 colours?

Question

why does a rain have the colours it does?

is their any significance?

Answer 1

Only Leprechauns know the true answer.

Answer 2

It is actually a continuum of light frequencies from the infra-red (which we can't see) to the ultra-violet (which we can't see).

Answer 3

It doesn't!

The human eye can make out about six colours - but the rainbow in fact has a much broader spectrum.

Isaac Newton, for mystical alchemical reasons, felt seven was a significant number, so inserted the colour indigo, which most people agree was a figment - or should that be pigment, of his imagination!

Answer 4

Rainbows are optical and meteorological phenomena that cause a spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth's atmosphere. They take the form of a multicoloured arc, with red on the outer part of the arch and violet on the inner section of the arch. More rarely, a secondary rainbow is seen, which is a second, fainter arc, outside the primary arc, with colours in the opposite order, that is, with violet on the outside and red on the inside.

A rainbow spans a continuous spectrum of colours. Traditionally, however, the sequence is quantised. The most commonly cited and remembered sequence, in English, is Newton's sevenfold red, orange, yellow, green, blue, indigo and violet.

Answer 5

It has 7 colours because the song says so..;-)

..none of this nonsense about the human eye only seeing a certain spectrum of light....etc. et.c

Answer 6

The spectrum actually contains six colours.

Issac Newton thought that there should be seven colours (due to his religious beliefs), so he defined the colour indigo as to satisfy this requirement (even though indigo is not particularly distinguishable from the other colours).

Of course the electromagnetic spectrum is continuous, so in reality no one colour is more significant than the others anyway.  If we had better eyes then we could see more colours that we currently do (such as gamma rays and microwaves).

Answer 7

It doesn't have exactly 7 colours. It has a much broader spectrum (the whole visible spectrum in fact).

If you split a beam of light with a prism you can see the spectrum more clearly

Isaac Newton decided that there should be 7 colours, based on some spirtual attachment to the number 7. (Holy trinity plus 4 gospels? I don't know...)

Answer 8

It's the color spectrum that is reflecting in your eye's color rods. Sunlight contains all the colors that reflect off of objects into our eye's color rods that act like prisms, like a rainbow, and we see the reflected light off an object that is reflecting the colors of the object. The rain acts like a prism that is reflecting the sun's light spectrum. If you damage or take out your eye's color rods, the colors wouldn't be reflecting accurately and you would be color blind, and with no rods, everything would look like a black and white movie.

Rainbows are optical illusions that only exist in your eyes and your brain being connected to your eyes. Rainbows are curved because your eyes are curved. And why everyone can see a rainbow at the same time is because our bodies are the same.

Answer 9

rainbows are arcs of coloured light formed when the Suns rays are reflected and refracted (bent) by drops of water in the air - falling rain or spray. the colours in rainbows are red, orange, yellow, green, blue, indigo and violet. a rainbow with red on the outside and violet on the inside is called a primary bow. sometimes, the light is reflected twice and the colours are reversed in a secondary bow.

only half of a rainbow is visible, the lower half being cut off by the ground. a complete circle can be seen from an aeroplane.

Answer 10

It is because, the sunlight which is mainly responsible for the formation of a rainbow ,is supposed to contain seven colours only.

Answer 11

it has more than seven doesnt it

unlike pictures of rainbows in a real one they all fade into each other making alot more colours

Answer 12

There's not enough room for any more.

Answer 13

Because the rainbow maker couldn't afford any more.

Answer 14

It does NOT have seven colours

it is an analougue graduation and has a graduation of colours.

we split it up into 7 for our convenience

People could have given it 9 or 14 or  124 colours, but we call it seven, because our perception makes it easier that way

Answer 15

because there alll travelling at different speeds, not that the eye can tell

Answer 16

A rainbow contains all the colours of the spectrum of which there are 7