You are actually taking a photograph of sunlight being reflected by the surface of the moon. You basic ball park setting would be 1/(ISO) for a shutter speed and an aperture of F/16, a basic well lit setting for full sun. If you are using ISO 200 your exposure would be 1/200 of a second using F/16 if you are shootting close to a full frame image of the moon.
Canon 40D
Canon Digital Rebel
Canon EF-S 10mm-22MM
Canon EF-S 18MM-55MM
Canon EF-S 60MM Macro
Canon EF 28MM-135MM IS
Canon EF 75MM-300MM IS
Olympus 725SW