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Is the red visible to the naked eye?

17 hours ago, Ashwin Tyson said:

Is the red visible to the naked eye?

I am not the guy who made this time lapse but to answer your question, Yes 

i mean photo...whoops

On 11/22/2021 at 9:02 AM, Ashwin Tyson said:

Is the red visible to the naked eye?

yes it was Ashwin, less so than the green, but still visible that night. 

 

Beautiful pictures, thank you so much! 😍🙏 What makes the green and red? Wondered some time. And yellow? 😲❤️ Didnt know it could be yellow. 

6 hours ago, Miss Sunshine said:

Beautiful pictures, thank you so much! 😍🙏 What makes the green and red? Wondered some time. And yellow? 😲❤️ Didnt know it could be yellow. 

Copy-pasted from Wikipedia: (short answer, excited oxygen at different altitudes)
 

Oxygen emissions

green or orange-red, depending on the amount of energy absorbed.

Nitrogen emissions

blue, purple or red; blue and purple if the molecule regains an electron after it has been ionized, red if returning to ground state from an excited state.

 

Oxygen is unusual in terms of its return to ground state: it can take 0.7 seconds to emit the 557.7 nm green light and up to two minutes for the red 630.0 nm emission. Collisions with other atoms or molecules absorb the excitation energy and prevent emission, this process is called collisional quenching. Because the highest parts of the atmosphere contain a higher percentage of oxygen and lower particle densities, such collisions are rare enough to allow time for oxygen to emit red light. Collisions become more frequent progressing down into the atmosphere due to increasing density, so that red emissions do not have time to happen, and eventually, even green light emissions are prevented.

This is why there is a color differential with altitude; at high altitudes oxygen red dominates, then oxygen green and nitrogen blue/purple/red, then finally nitrogen blue/purple/red when collisions prevent oxygen from emitting anything. Green is the most common color. Then comes pink, a mixture of light green and red, followed by pure red, then yellow (a mixture of red and green), and finally, pure blue.