Hi Woozy,

The update of the server happens at 1:20 a.m. server time, at which time the new destroyed planets are registered, and the registered destroyed planets are erased.

So you need to wait two updates to recolonize a position.

Have a nice game

The destroyed planet disappears at the second 01.20 (server time) after that has been abandoned. So the time can be slightly more than 24h until very close to 48h.
There could be a little lag for this, if i remember well. You can check until 01.25.