Question #8afe1
1 Answer
There is already a very good answer to this somewhere on the site, but I’m unskilled so (a) can’t find it (b) don’t understand how to link things if I could. See below ....
Explanation:
You need to understand the dispersion of light by a prism / object of higher density to “get” the physics (try this: http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/prism.html) but here goes.
Stars’ light appears to come from a point (they don’t appear as ‘disks’ even using our best telescopes) so when the turbulent atmosphere refracts (bends) the light slightly away from your eye it is easily seen as one of the ‘rainbow’ colours that appear off at an angle compared to white light (the mixture of colours we call white.)
As the atmosphere is constantly churning due to warmer/cooler parts mixing (just like we see “ripples” of air above a BBQ or fire) the light varies in colour and intensity very quickly - the effect we call twinkling.
Planets’ light also passes through the atmosphere, but is unaffected - why? Simply because the light appears to come from a small disk, so if the light is bent away on one edge, the whole of the rest of the disk is still shining steadily with white light into your eye. The effect exists, but is much less noticeable.
Both effects (turbulence and consequent rapid colour changes) are more apparent the closer the object lies closer to the horizon because when you see the light it has passed through a much thicker layer of air.
Hopefully a moderator/intellectual/Demi-god will manage to link this answer to the ‘proper’ one.
