THE orange and red tints that the Sun and Moon sometimes take on are caused by particles in the Earth’s atmosphere.
[ihc-hide-content ihc_mb_type=”show” ihc_mb_who=”2,3,5″ ihc_mb_template=”1″ ]When light (or more specifically, packets of light called photons) from an astronomical object passes through the Earth’s atmosphere, it scatters off particles in the atmosphere.
It turns out that these particles like to scatter blue light more than they do red light; so “bluer” photons tend to get scattered, and “redder” photons pass through.
So, astronomical objects look redder from Earth than they would from space, because the redder wavelengths from the objects penetrate the atmosphere better than the bluer ones.
Incidentally, this is why the sky is blue: blue light from the Sun is scattered in all directions on its way to the Earth.
You also may have noticed that the Sun or Moon sometimes look reddish when close to the horizon.
If you think about it, sunlight or moonlight must travel through the maximum amount of atmosphere to get to your eyes when the Sun or Moon is on the horizon (remember that that atmosphere is a sphere around the Earth).
So, you expect *more* blue light to be scattered from Sunlight or Moonlight when the Sun or Moon is on the horizon than when it is, say, overhead; this makes the object look redder.
In other words, the Sun or Moon tends to look orange or red when it is rising or setting because that’s the time when the light has to travel through the most atmosphere to get to you.
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