So Nuni declared that heaven is not up but underground. When I asked her why, she thought about it for a couple of seconds. First she said that rockets go to outer space so maybe heaven is there. Then she thought a few seconds more and explained it away like this:
When a plane goes up in space we can see the clouds but no heaven. But, zombies are normal people who die and rise up from the ground and they came up in a different form. The others who die and are buried, stay there in heaven.
Just to be clear:
The good people get to stay in heaven and get to do fun stuff. The others who do bad things come back in weird skin forms (their souls get these weird skins) when they come up as zombies.