Since the night two days ago, the moon here in Israel appears to be orange as it rises, and then gradually becomes white as it continues travelling across the sky.
This phenomenon has a great timing as I am starting to become interested in astronomy (I have no special knowledge in astronomy). So I googled up and came across this explanation.
I'll try to summarize: it says that it happens because of Earth's atmosphere, that tends to scatter short wave-lengths (such as blue and green) and let long wave-lengths (such as red and orange) pass through. When the moon rises, it's in the position where the light coming from it to our eyes goes through the thickest layer of atmosphere (as opposed to when it's high up in the night skies) and that gives the orange effect.
I understand this explanation, but it raises a couple of questions for me.
- Why doesn't the orange moon phenomenon occur all the time?
It does not happen quite often. What's so special about the past three nights? I mean, the rising moon's light always has to go through a thick atmosphere layer, doesn't it?
- Maybe that's not entirely astronomic, but, to complete the big picture - why does our atmosphere scatter short wave-lengths?
- This explanation suggests that all light coming to us from the sun is (at least) slightly reddish. Is this measurable (if true)? Because to the naked eye, sunlight refracted through a prism shows no tendency towards red.