There is this new proposal that is quite hot on Area51 now. Scientific Imagination. As it's description says, it is for the people who are interested in questions involving imaginary scenarios and scientific, educational, and fun answers for those questions.
I found some questions that might be on-topic here:
- What would happen if the sun was instantly replaced by a black hole with the same mass?
- If objects in Kuiper Belt and Oort Cloud could be amassed to a single planet, what would it be like?
- If we count Avagadro's Number of stars that are closest to Earth, how big that space would be?
However the difference of this from Stack Exchange science sites is, the proposal is intended to be like what-if.xkcd.com. So it does not only ask for answers, but also invites answerers to let loose their imagination.
Do any of you think this proposal could be a partial duplicate of Astronomy?