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Sky color on extrasolar planet

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amitakartok Since: Feb, 2010 Relationship Status: Don't hug me; I'm scared
#1: Mar 9th 2015 at 4:53:18 AM

Suppose there's a super-Earth planet orbiting a Class M red dwarf in the habitable zone (tidal locking is irrelevant). The planet's atmosphere is a nitrogen-CO2-helium mixture, with no surface water (and thus no clouds). Atmospheric density is similar to Earth's.

What color would the sky be? There's enough nitrogen to produce Rayleigh scattering like on Earth, which would make the sky blue - except this says a red dwarf seen through Earth's atmosphere would make the sky white, due to the star radiating less blue light photons than the Sun. However, this graphic does not take into account that this hypothetical planet's atmosphere contains carbon dioxide, which has a larger cross-section than oxygen when it comes to Rayleigh scattering, and in larger quantities than Earth's atmospheric oxygen content. Would the sky still be white in this case?

Would it be correct to assume the sky is white due to the above, with a slight yellowish tint as well due to atmospheric dust?

edited 9th Mar '15 4:55:40 AM by amitakartok

MajorTom Eye'm the cutest! Since: Dec, 2009 Relationship Status: Barbecuing
Eye'm the cutest!
#2: Mar 9th 2015 at 5:36:14 AM

Mars has a somewhat similar atmosphere minus the pressure and its sky is depending on time of day and weather conditions (yes there is weather on Mars) anywhere from red to pink to orange to blue (at sunset/dawn) and more.

"Allah may guide their bullets, but Jesus helps those who aim down the sights."
deadwaste Since: Aug, 2014 Relationship Status: It's not my fault I'm not popular!
#3: Mar 16th 2015 at 7:25:56 PM

Who cares? Just chose a color that's pretty and works with your planet. Worked for me and no one cared.

edited 16th Mar '15 7:26:32 PM by deadwaste

washington213 Since: Jan, 2013
#4: Mar 18th 2015 at 11:03:25 PM

Is the sky color with relation to exact chemical makeup of atmosphere a plot point? Then yeah, nobody is going to care.

Also, nobody should be able to prove you wrong unless you give exact percentages and stuff. And if you are, I would rethink offering up exact numbers like that since you don't know all the science behind it. There are always ways to work around stating exact measurements.

tiberius04 Since: Jul, 2012
#5: Mar 29th 2015 at 1:19:18 AM

Found a guide that might help: http://www.orionsarm.com/page/321

Sounds like you are probably right about the sky being white, unless there is atmospheric dust.

Noaqiyeum Trans Siberian Anarchestra (it/they) from the gentle and welcoming dark (Time Abyss) Relationship Status: Arm chopping is not a love language!
Trans Siberian Anarchestra (it/they)
#6: Apr 3rd 2015 at 6:21:12 PM

[up][up] Just because the author wants to know how the world holds together doesn't mean it's going to be explicitly stated in the story. At least 90% of the worldbuilding shouldn't be.

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