Heaven through the eyes of a child

So Reid has been talking a lot about heaven a lot. . . . where is it, when will he go, is Mimi there? I have been pretty good about answering most questions until he really stumped me the other day. We were walking home from school and he looked up in the sky and asked "Mommy which cloud is the heaven cloud?" I looked up and really didn't know what to say. How do you explain heaven to a four year-old? Finally I answered "It will be the most beautiful cloud you will ever see. If I ever see it I will show it to you." He seemed pretty satisfied with that answer. . . for now.