Now, I was looking the sky when I saw the Moon showing up in a sky completely cloudy, like this:

enter image description here

But a little different. The clouds were doing an eye shape. What does explain that phenomenon? Looks as if moonbeams drilled through the clouds!

  • $\begingroup$ not exactly theses optical phenomenon. What I saw was the same phenomenon than the picture. Showing a certain deep, from the clouds until the moon. Sorry it's hard to explain when I have no knowledge about it $\endgroup$
    – TMoraes
    Oct 27 '15 at 12:42
  • $\begingroup$ It's a sunny day on Earth's moon. That and what what @MichaelJRoberts said. $\endgroup$
    – Logan
    Jul 20 '16 at 11:21
  • $\begingroup$ my question is why does more light not show? surely the moon is not projecting a direct beam of light which only lights that small area of clouds. what is the phenomenon that only allows us to see the area directly in front of the moon light up? $\endgroup$
    – Sargent
    Nov 7 '17 at 5:19
  • $\begingroup$ @Sargent Please use the "Ask Question" link above to ask further questions. Thanks! $\endgroup$
    – called2voyage
    Nov 7 '17 at 13:23

That is called a corona. It is caused by diffraction of light by thin clouds with small but evenly sized particles. The best coronas show multiple coloured bands.

There is a similar, but unrelated, phenomenon, called a halo, which is caused by high altitude ice crystals with a regular hexagonal shape. It is much larger, 22 degrees wide.

Both these can be seen around the sun as well as the moon, and are fairly common, more common than rainbows (for example).


Clouds are obviously not completely opaque, and what you are seeing is a break in the clouds. It is of course possible for the clouds to cover the moon, however, often the moon can shine brightly through the clouds and illuminate the clouds in some nice way.

This video might help in a visual way: https://www.youtube.com/watch?v=aLd_yhIWE48


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