sun

Notice: The sign for sun uses a full "C" hand, whereas the sign for moon uses the thumb and index finger.

SUN

Here is a sign that could be used for "sun." It can also mean "sunlight"--especially if you bring the sign downward, (like a ray of sunlight coming down from the sky.)
Circle the flattened "O" handshape once and then bring it downward and open it up.

Question from a student: What's the sign for sunglasses?

Response: I tend to spell S-U-N and sign glasses.
Or I use the sunlight variation of SUN:
followed by the glasses/gallaudet sign:
http://lifeprint.com/asl101/pages-signs/g/glasses.htm
As with most compound signs, the movements are condensed and quick.
--Bill