I destroyed a planet with another planet, as you do, and I had bound my view using alt-4 to the asteroid. After the planet was destroyed, when I used shift-4 to go to the destroyed planet, it showed me the planet, intact, inside the sun. I thought that was odd and moved on. A minute or so later, I did it again and the game tripped out. It stopped rendering the scene, I assuming the camera viewpoint was set to NaN or something, and I couldn't move back to see the other planets or change to them with shift-X. A couple of seconds later the game crashed.
The planet is being hidden inside the sun and i guess it is done that way for the chronocam tech. If the planet was destroyed and removed from the scene it would most probably be destroyed in the RAM/ GPU memory too. In that instance if you were reviewing chronocam and rewound the game from the time the planet was destoryed to a point before that it would have to "Regenerate the planet real-time" and with the complexity of those sphere's that is not going to happen quickly.. Easiest option is to "Stash" the destroyed planet somewhere hidden in the scene when it's destroyed then when chronocam rewinds the game it doesn't need to regenerate the planet it just "unhides" it from it's "Stashed" position and plays the game in rewind without the need to regenerate the planet in ram real-time.. I hope that sort of clears up why it maybe done like that.. It's a very similar technique used in the 3D Computer Graphic Animation software i use personally..
Currently, dead planets are hidden in the sun. This will remain the case until we have a system to remove dead planets from the game.
Sounds about right. We just need a mechanism to hide dead planets (just make them invisible so we don't have to regenerate them later) and let the client know to ignore them.
I have also seen unit icons for the commander and bot fabber inside the sun while their astraeus was moving to another planet.