Something I've noticed

[Manok101]

Occasionally if I look at a star just right, say if it's not focused just right or something I have noticed that they will flash, like I noticed Betelgeuse will flash green and red. the middle star in orisons belt is blue white and red... Is this my eyes plowing tricks? Or an atmospheric thing? Or what?

[KevG]

You are correct regarding the atmospherics. Stars twinkle due to a turbulent atmosphere, the light is refracted hence the colour shift. Twinkling stars are always a good measure of the seeing conditions, which of late have been rubbish around my neck of the woods