How come there aren't stars of different colours like purple or green stars?

Question

I think a green star or purple star would look awesome, a green or purple sun set on a alien world would definately be a weird thing to see.

Answer 1

The colors our eyes see are fine-tuned by evolution to detect only a narrow part of the spectrum where most of the Sun's energy is concentrated, between 400 and 700 nm, centered at 550 nm. All the colors you and I see are in this narrow range: from violet at 400 nm to red at 700 nm. Each perceived color in this range is quite narrow, amounting to typically 50 to 80 nm only.

But stars, like the Sun, do not put out light in narrow ranges. They radiate light in very broad ranges -- which is why the Sun itself looks white to the eye: it's radiating strongly across all the colors we can see. If the Sun were radiating ONLY at 550 nm, it would look green.

Now stars DO have different colors, caused mostly by their different temperatures. But those are colors only in the very broad sense, that the center of their outputs are shifted away from the Sun's 550 nm center, more to the red end, or more to the blue end. But almost all stars still radiate strongly across the entire human-visible spectrum, so all of them look whitish -- just a bit on the red side, or a bit on the blue side. Occasionally you will run across a red giant that looks extremely red, but that's about as good as it gets, in terms of star color.

Answer 2

Star colours mostly come from a phenomena called "black body radiation" and are related to heat.

As the temperature gets higher the colour goes from red to orange, yellow and then white. A very hot star is a bluish white.

You get the same effect on earth through heating something like metal to a few of thousand degrees.

Answer 3

Actually our Sun light radiation spectrum leans towards the Green. It could be called a green Star. However ;our naked eyes see it as yelowish.
Note ;the folliage of all are trees are basically Green.They where designed that way so they would resonate with the Green spectrum radiation from the Sun. Thus absorbing more energy than if the leaves were black.

Answer 4

Wien's Law states that a hot object will radiate most in the wavelength that cooresponds with its temperature. You can see that happening when you stick a fork in a fire. As it gets hotter its color changes from red to yellow to blue and then white.

Stars do the same thing. The "cooler" stars are red, meduim are yellow and hottest are blue.

Answer 5

Stars come in blue, red, white, orange and yellow. You want a Bob Ross painting set of stellar objects?

Answer 6

Fusion reactions are pretty 'picky' about what's in their fuel. And most of the common trace elements don't have any spectral lines n the blue or violet.

Doug

Answer 7

Jeez, such long-winded answers above.

In short, they do come in various colours.

Buy some binoculars.

Answer 8

Observe Sirius and note its color.

Answer 9

How about striped ones? :) Now that would be really cool.

Answer 10

maybe they are those colors. they're just so far away that you cant tell.