Tweet
(off topic: depending on eyesight and atmospheric conditions, I can visually pick out planets from stars by noting that direct energy sources like a star twinkle, whereas planets and other objects that reflect light are somewhat light-stable. Lots of squinting.
Thanks gravity!
The sun is a direct source, and if you use a filter to be able to safely look at it it will not twinkle.
For a point source there is exactly on path through the atmosphere from that source to your eye (well, a bunch of paths because the lens of your eye has some extent too.) Changes in refractive index, dust particle, and lots of other random events in the atmosphere, from top to bottom, affect the light transmission from that point source.
For a larger object, like a planet or the moon, there are multiple paths from any particular part of the object to your eye and the brightness fluctuations from path variations cancel each other out.
For a point source, using a telescope with a much larger aperture then the eye will also average out the light intensity and reduce the twinkling.
A person in space or on the moon's surface will not see the stars twinkling. It has been described as a somewhat disconcerting experience. Not what we are used to.
Comment