Why are there no Purple Stars? or Green Stars?


There are red, orange, yellow, blue, and even white stars, but no green or purple stars. The reason comes down to chromaticity and the optics of black body sources. Brilliant for 20% off:

How Do We Know Things About Stars?

The Color White Does NOT Exist:


MinutePhysics on Chromaticity:

SciShow Psych on Color Perception:



Advanced Theoretical Physics (Paperback):

Advanced Theoretical Physics (eBook):



Warden of the Asylum:

Asylum Counselors:
Matthew O’Connor

Asylum Orderlies:
William Morton, Fabio Manzini

Einsteinium Crazies:
Albert B. Cannon, Wacky, Eoin O’Sullivan, Ken Davis, LT MarshMan, Ilya Yashin

Plutonium Crazies:
Al Davis, Kevin MacLean, Randall Sylvia

Platinum Crazies:
Mikayla Eckel Cifrese, Stephen Blinn, Vittorio Monaco, Felipe Cruz, Eugene Boone, Rick Dinning, Mr. Orn Jonasar, Jon Adams, Kyle Bowles, Jonathan Reel

Chromaticity Graph Generator:


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  1. Note: You won't find colors like brown or grey on the chromaticity graph in this video because it's only a 2D slice of the actual graph. Actual chromaticity requires a third axis, a lightness/darkness axis, to show the darker versions of colors. Brown is dark orange, grey is dark white, etc.

  2. so the sun is actually green or should have been green (the sun is white) to us but thanks to jiggling, monochromatisation and our limited perception we see the sun as white (yellow due to the atmosphere)
    like wtf?

  3. Thanks for that RGB but how can it fake it.
    But why after 45000 K it's infinity in that temperature curve? So sudden? Plus why are calling violet as purple? I think violet is a separate color and blue + red is purple, right? But u removed V from screen, called it purple

  4. subbed…this is an awesome channel…it answers all my questions after studying black body radiation…

  5. You can see the purple time outside the jar. The eyes can translate the blue color inside the galaxy, as you explain.

  6. This video needs more views! People need to be educated about the discrimination of black body radiation curve and monochromaticity on green and purple.🤜🏻🤛

  7. When you say the colours outside the visible spectrum don't matter is that literal or a simplification? If you, for example, sent ultraviolet and red light at the same time would it not look blue-ish from the light combining (or at least more blue than the red light alone)?

  8. what if there was enough molecular compounds i nthe start that emit in the green light? like copper,
    OR could there be any non-thermal processes that could dominate in the green part?

  9. You're not scientifically correct here. It's called electromagnetic spectrum, not light spectrum. Light is only the visible part. Saying "visible light" is a pleonasm, a useless, redundant name or phrase. There is light, and there's other kinds of radiation. Light is visible electromagnetic radiation.

  10. and brown star? when I go to the restroom in the morning after the breakfast, a brown supernova explodes and fills the porcelain receiving parabolic dish of my astrocoprological radiotelescope with so much brown light i cannot even flush it afterwards.

  11. This was one of the most brilliant videos I have ever watched
    I totally understood this fascinating topic
    thank you

  12. Can we mix this interpretation with doppler effect?
    Once more, thanks for your service. This video is magnific!

  13. As the visible spectrum can be represented proportionally ,as the width of a cotton thread ,with the other wavelengths making up the distance from New York to California This looks like a similar proportionality to the stars and planets ,against empty space in the Universe

  14. so isnt it wrong to distinguish stars based on colour only in our vsible range of spectrum,
    i mean we might have a war with some alien species based on what colour does a star is.

  15. Great summary…….hadn’t focused on this specific topic since taking undergrad astronomy courses over 30 years ago.

  16. You explain well why there are no green stars because it is in middle, so it is even to left and right color that will equal white, but not about equal but even amount of color, so middle color and middle temperature. But the temperature is not even, so it can go higher since it is not actual middle in term of everything, it is in middle for number, but the numbers itself is 3000 increase to 7000, then far higher than double of 3000 of left to right, so it would be up to 11,000 as a total, but you go higher than that, so 7000 is not true middle, so middle is not accurate, but you say balance. So, green is in balance so we see white that is logical, but also we see green in other things, but not white, but those are not color of balance to equal white. So, can explain how equal color to equal white? So, base in understanding for white is base on all color on frequently which show white and within white is all color. So, white is overlap, so it is not monochromatic, which you mention monochromatic, so it is one color. So, all color is monochromatic? So, all even monochromatic colors make it white, but the temperature is low enough, so it has some blue and some purple, and other color, but not too much as it would show higher color since the color depends on temperature.

    So, it is not a primary color, but primary heat which causes the color within how much impact of energy per time to cause the color to increase that match visual color frequently for a range of low to high nm, and in connecting to nm, is heated. So, you haven't explained why star can't go high enough to be purple?? And beyond the temperature is non-visual frequently, which goes to higher frequently so you will see black, but it exists so it is so hot. So, there is two range of non-exist but exist that is non-color which you can't see visually because you only see visual frequently. So, the color of the star is so low, you can't see the color, but it is there and the temperature is so low as well. So, there is a connected relationship between frequency and temp. So, in connecting to heat that is star, in connecting to non-heat that is a regular color that is dipole radiation which causes the rate of depth for how much energy to go up and down that convert into color into your eye. But other colors that we know as non-heat but it has color. Ok, the star has an extra to justify the heat with color because it is within high pressure so with dipole so it radiates color base on the dipole, so it is high pressure and range of resonating of dipole radiate. So, it is not just color, but it is also pressure which you haven't explain. So, the star is not in enough pressure so it doesn't have enough of higher energy to create a resonate to cause color for purple. So, I explain to myself why there is purple which you didn't. Well, dipole radiate is depend by materials itself, not one material in connecting how much impact from light that is hitting it to cause it to radiate out. So, the color is dependent by depth of resonating that is dipole radiate of color. The material can change to different color depend how much impact from light to radiate out. Because color is depended on the interaction of light and mass, part of the mass that is a depth of electrons. So, the sun depends on rayleigh scattering that causes you to lost color or not in connect to dipole radiate which you didn't include in the video above like it is both different.

    Ya can include thinking clone to ask smart questions base on all info in past to counter back so you update the video. NOt questions clone which it is a surface answer, but not deep questions for it is not enough to answer why it is purple.

  17. Short and very inaccurate answer: the Sun IS green, but due to the way light works, everything else emitted in the visible spectrum causes it to even out to white.
    And purple stars can’t exist without being overpowered by blue.

  18. The explanation for no purple stars was simple ("purple's not on this curve!") but unsatisfying. Should have just explained that true purple is a fake color anyways, one invented by our brains that corresponds to no real wavelength of light.

  19. So if you see a purple or green Star you are either mistaken, or else looming at an artificial star. Got it.


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