Post 556319 by ej@mastodon.me.uk
 (DIR) More posts by ej@mastodon.me.uk
 (DIR) Post #272069 by ej@mastodon.me.uk
       2018-09-24T19:45:02Z
       
       0 likes, 0 repeats
       
       Mysterious phenomenon (and also embarrassing thing wot I did during a recent maritime aviation exercise):Reported an aircraft inbound to the ship, facing us head-on (deduced from being able to see both its red and green sidelights).It was inbound for a *really* long time.It was, in fact, Capella.I didn't even know it was possible for stars to twinkle red-and-green!(Since then, I have been looking out for ones that do; the best examples I've seen so far being Sirius and Betelgeuse)
       
 (DIR) Post #272070 by icefox@octodon.social
       2018-09-28T15:27:27Z
       
       0 likes, 0 repeats
       
       @ej The twinkling of stars is due to the changes in the density of the atmosphere, just like heat-shimmers over a hot road, on a large scale.Like all transparent materials, the amount that air diffracts light is based on wavelength.  All transparent materials split light like prisms all the time, it's just usually a very tiny effect.In your case, essentially, the changes in atmospheric density were right to break colors enough for you to see.Bad pre-coffee explanation, but hope it helps.
       
 (DIR) Post #272080 by icefox@octodon.social
       2018-09-28T15:28:41Z
       
       0 likes, 0 repeats
       
       @ej This is probably more common than we think; humans don't see color very well in low-light conditions.  I'd guess you get brighter stars and darker skies at sea without much light pollution.And Betelgeuse is pretty obviously red already.
       
 (DIR) Post #556319 by ej@mastodon.me.uk
       2018-10-15T19:54:51Z
       
       0 likes, 0 repeats
       
       @icefox Thanks loads for the explanation - I really appreciate your taking the time and effort to provide one - but this does kinda seem to yield more questions than it answers!• Prisms produce a static pattern (if you were in the "red sector" you'd see only red), but the star alternates between red & green?• Only red & green, though the original starlight must have more than just those wavelengths?• The atmosphere is constant for all stars, but only a few seem to do this?
       
 (DIR) Post #556353 by ej@mastodon.me.uk
       2018-10-15T19:56:57Z
       
       0 likes, 0 repeats
       
       @icefox Yeah, except for a few days around the full moon, the skies are very dark and the stars, planets and Milky Way seem really bright. I find it really beautiful!
       
 (DIR) Post #695958 by icefox@octodon.social
       2018-10-22T17:45:30Z
       
       0 likes, 0 repeats
       
       @ej I BELIEVE these are the answers: * prisms produce a static pattern, but the atmosphere itself is moving around a bit, so you're looking through denser and less dense areas as you see the start. Imagine you're standing in one place and moving the prism back and forth a little as you look at it.* I know the human eye is more sensitive to red and green than to blue, so with a faint light you might just see those colors most clearly?* Again this might only happen with the brightest stars?
       
 (DIR) Post #695974 by icefox@octodon.social
       2018-10-22T17:46:14Z
       
       0 likes, 0 repeats
       
       @ej Those are my guesses from what optics and astronomy I know, at least. If you're a redditor then /r/askscience is a great place for this sort of question and you'll probably get far better answers.