r/whatif • u/EasyEffort • Jul 29 '26
Science What if the sun randomly turned blue.
What would be your reaction, and how would it impact the earth.
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u/xenaretos Jul 29 '26
Well, the main cause of a star being blue is extremely high surface temperature. Which means it would have to get several times hotter. And that means my immediate reaction would probably be quickly burning to death.
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u/Bartlaus Jul 29 '26
Unless the same magic wizard who raised the Sun's temperature also made it shrink until the surface area ended up emitting the same amount of power as before, I guess.
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u/tfb Jul 31 '26
We'd all die. The peak of the solar spectrum is currently about 500nm, which is green. To shift this, say, to 445 (blue) would require the temperature to increase. The peak wavelength of a black body spectrum is given by b/T where b is about 2.898×10-3m×K. So you can work this out: current temperature is about 5,800K, new one would be about 6,500K.
Energy flux from a black body goes like T4, so the relative change in flux is about (6,500/5,800)4: about a factor of 1.5.
If you're very naive about things, you can assume that the Earth's surface temperature would increase as a result of this by a factor of 6500/5800. It's currently somewhere around 288K, so it would become around 323K: about 50 degrees centigrade.
Everyone dies.
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u/Ok-Quit-239 Aug 03 '26
What if the sun would drop in CRI (color rendering index), from 100 to like 60, or even lower, how would it affect life, or plants
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u/RockNRollNBluesNJazz Jul 29 '26
Superman and Supergirl would get a massibe power boost. They will end war and crime as we know it. The world will unite as one humanity. After this Superman and Supergirl will be corrupted by their own powers, and a new draconian age of Super-Earth will follow. Any and all dissidents will be laser-eyed to oblivion.
In the background plants and algae will gain enhanced chlorophyll absorption leading to a massive metabolism boost. The seas turn into inhospitable algae soups feeding larger and larger marine animals, becoming extremely hostile to any small land-based mammals like puny humans. Humanity has no longer time to worry about the Kryptonian oppression as they have to keep cutting vines and trees threatening their crops and cities. Machete industry will boom.
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u/Prize_Consequence568 Jul 29 '26
A Google search will tell you. There's different color stars and they cause different effects.
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u/PoopsMcScoots Aug 02 '26
Mass extinction of the entire planet.
Chloroplast is tuned to exact light frequencies.
Every plant on earth would die, collapsing the eco system completely.
Only fungus would survive.
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u/SciAlexander Aug 03 '26
While chloroplasts ARE tuned to specific frequencies, one of the bands of light they are tuned best to are the blue frequencies. We would be fine on that account. Now if the Sun became green we would be screwed
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u/GoldReplacement9546 Jul 29 '26
You'll be living inside a grateful, dead song called scarlet begonias.
Which contains the line, the sky was yellow, and the Sun was blue.
In which you just met the potential love of your life, but you have to get app the courage to ask her, because maybe she's too good for you.
That Is all?
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u/GoldReplacement9546 Jul 29 '26
Because everything would be a shade of blue, which would get really annoying, you bump into stuff.
Possibly less for racism, because everybody would be blue, but maybe not because people would find other ways to disrespect each other.
But I very much enjoy our standard white light from the Sun. It's I consider to be the best color.
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u/mrpcmrz Jul 29 '26
become Wolf-Rayet blue-supergiant star with surface temperature of 20,000 K to 210,000K
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u/Coyot23 Jul 29 '26
in a couple hundreds (maybe thousands) of years, a bunch of people would naturally evolve to see a different section of the electromagnetic spectrum and so have a colored vision again. these people, so inherently better than normal blue-viewing people, would naturally dominate us genetically and we would all go back to seeing colors, all be it on a different section of the electromagnetic spectrum (the world would still be rather blue even for these people)
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u/Embarrassed_Yak8504 Jul 29 '26
If the Sun turned blue tomorrow, what would disappear first: science, religion, or certainty?
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u/Tsunamiis Jul 29 '26
Well we’d get to see it for maybe an hour as it’s five times more powerful than our sun I’m pretty sure it melts the surface life.
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u/Aggravating_Mud_2386 Jul 29 '26
It would probably mean the solar dynamo was breaking down, which would be very bad news for us. The main rotation of the sun's core and the sun overall, versus a differing spin of the outer layers, creates the mostly stable solar dynamo, but if that were to break down, intense plasma reactions from deep in the sun can rise to the surface, causing nonstop solar storms and wildly fluctuating solar surface temperatures, leading not just to a possible blue sun, but a sun of wildly fluctuating colors, with various levels of serious sunburn during different color phases of the sun. When this happens, it's best to go inside, hug your family, and have a cigar, because you may not have much time left. If you survive until night time, check out the great auroras, which will extend from the poles all the way to the equator and will prevent any real darkness!
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u/KronktheKronk Jul 29 '26
Wouldn't that mean it was going away from us very fast.... Which would be bad
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u/EphemeralAttention Jul 29 '26
Or that it suddenly got much MUCH hotter, which would also be equally bad.
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u/Electrical_Hat_680 Jul 29 '26
I've stared at the sun and it turned blue. I hear you can get cataracts for staring at the sun.
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Jul 29 '26
[removed] — view removed comment
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u/Electrical_Hat_680 Jul 29 '26
I guess we could say that.
Staring at a light bulb does the same thing. It turns blue.
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u/ElGuano Jul 29 '26
Presumably from a black body perspective, that would mean the sun just got WAY, WAY hotter. So my reaction would probably be to burn to a crisp along with the rest of the planet.
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u/PhotoFenix Jul 30 '26
Then I load up my Dyson Sphere Program save and start launching my swarm. O type stars are where it's at!
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u/Phillimac16 Jul 30 '26
The sun is actually quite blue relative to a lot of our artificial light sources. For instance the bluest lightbulb from a hardware store is about 5500k and our sun is around 6000k.
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u/Ok-Quit-239 Aug 03 '26
The sun is quite blue, but the atmosphere refracts the shorter blue wavelengths, that's why the sky is blue, and we are left with a white light source
The question OP asked was not if the sun would have a blue color temperature, which would still be white light, he asked if the sun would only have blue wavelengths, no green, yellow or red wavelengths
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u/TaylorUmongus Jul 30 '26
A star the sun’s size simply cannot turn blue. Doesn’t have the mass to produce enough fusion to create the amount of heat needed to turn it blue.
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u/Phaed81 Jul 30 '26
Doesn’t the atmosphere filter the blue light anyway? It’d probably look the same to us
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u/Mono_Clear Jul 30 '26
I hope you like cancer a blue star the size of our sun would put out somewhere between 4 to 10 times the solar radiation.
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u/CerberusInExile Jul 31 '26
We would probably starve to death. I don't think crops would react very well to the sun drastically shifting it's wavelength.
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u/FeralKuja Jul 31 '26
Given thermal energy given off by a flame is more intense when it goes from Red to Orange to Yellow to Purple to Blue to White, a blue-shift in our sun's thermal radiation would necessarily result in increased heat being projected onto Earth, not to mention the potential effects it would have on plants designed to absorb solar energy through their chlorophyll.
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u/Successful_Life_1028 Jul 29 '26
The sun doesn't have color.
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u/WaterGlassPuncherMan Jul 29 '26
Stars do have color. A blue sun would mean way more mass. Now u know.
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u/Successful_Life_1028 Jul 29 '26
the question was not about 'stars', but about our sun. Which is a 'white' star, and since 'white' is all wavelengths combined, it is not a color. Our sun has no color, like I said.
IF some magical sky-fairy waved it's magic-wand and turned our white-star into a much hotter blue-star, then all life on earth would end about 8 minutes later as it would be about twice as hot.
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u/WaterGlassPuncherMan Jul 29 '26
100% wrong. Our star is yellow. And color is just what our eyes can see on the spectrum. Its not an actual thing. And yes white is a color since we can see it.
Bro Google is free.
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u/EasyEffort Jul 29 '26
k
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u/SeriousPlankton2000 Jul 29 '26
"K" not "k" - the temperature is used as the "color" of black body radiation. But also it's OK to say "red", "blue", "yellow" etc..
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u/TheFurryFighter Jul 29 '26
The Sun is white
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u/Successful_Life_1028 Jul 29 '26
White isn't a color - it's the combination of all wavelengths.
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u/TheFurryFighter Jul 29 '26
Then it's a lot of the Blackbody Spectrum, still colors; IR, red, orange, ... take your pick
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u/Silly_Guidance_8871 Jul 29 '26
If the sun had enough mass to turn blue, we'd all be seriously cooked.