Have either of you found anything that helps?
For us (and this wouldn't be universally helpful, I understand), it usually starts a discussion about our faith.
Space_Cadet - excellent!
On the other hand, DD8 talks about the death of the sun and the end of earth regularly, not in a concerned fashion, but just because she is interested in space and the universe. She was telling DS5 about this the other day, but told him "but don't worry, it'll be long after we're dead." DS took that in stride, "Yeah." Strange conversions my DC have...
