Now that Universe Sandbox has realistic galaxies that are now complete and which works properly, it is time to turn to nebulas. Yeah, that's right "nebulas". Nebulas in Universe Sandbox only exists as simulation backgrounds, but that's not enough. Developers must start development work to implement real nebulas in Universe Sandbox.
Nebulas must have many properties just like galaxies currently does. Nebulas comes in all shapes and colors, so this would be very interesting to add and simulate in Universe Sandbox. Please can you developers add nebulas on your todo list and start developing them. Nebulas must be added at some point. I would suggest adding them after the release of planet grids update.
Also, simulating the creation of nebulas when stars goes supernova is something that I would consider to be added as a new physics system for nebula creation when stars explode as well as spawning in nebulas just like users do when spawning galaxies into a simulation.