why does venus flicker?
I was watching Venus with the naked eye yesterday at about 7 pm and I noticed that it was flickering, almost like a star.
I have always learned that planets don't flicker to the naked eye, only stars (indeed, every other time I've seen a planet it wasn't flickering), so I was rather confused. I even checked Stellarium to make sure that what I was seeing was, in fact, Venus.
Does anybody have an explanation for that behaviour?
Thank you all.
Personally I've seen Mars scintillate almost every time I've watched it, so I can tell you that planets are capable of flickering. In Mars' case it's more of a change in color than a change in brightness; I'm not sure why. I've never seen Venus scintillate, but then I don't go looking for Venus very much at all. I've never seen Jupiter or Saturn scintillate though, probably because I only notice them when they're high in the sky at night.
Because planets actually do twinkle. Most people were told that the major difference between stars and planets is that only the former twinkle - but that's an oversimplification. Given the right conditions, planets will twinkle too, it just happens more rarely.
Several factors that contribute to it:
lots of air turbulence; or, as astronomers call it, "bad seeing"
closeness to horizon; if the planets are high in the sky, the air column is shorter so there's less chance they will twinkle; but when they are low, their light goes through more air and so it is perturbed to a larger degree
The observation you've made, Venus twinkling, is not very unusual. Many stargazers are used to seeing that once in a while. I've seen Venus scintillate several times in the past, always at sunset when it was about to drop below horizon; I would presume you could see the same behavior very early in the morning as Venus has just risen.