That's no moon, it's the Cylinder Hemisphere 11x11 (Death Star), LEGO® Part# 98115 + 98114. This product comes with two parts including part# 98115 and part# 98114 to make a complete Death Star. 

Appeared in set# 9676-1 (TIE Interceptor & Death Star). 

To learn more about the parts we offer, call us at our storefront at 470-414-2208 and we'll be happy to help.