Originally Posted by
Peter Toth
Regarding Universe Sandbox, despite some minor limitations, I absolutely love the program. When I say "limitations," I'm referring to a lack of accurate modeling to correlate magnetic field to the core size and rotation rate, for example. (Increasing rotation rate or iron core mass doesn't affect the magnetic field.) Also, the temperature modeling for satellites of brown dwarfs is unrealistic, as I discovered for my last project, Kaunis. Moreover, it's currently impossible to simulate accretion from initial parameters (of dust cloud angular momentum, protostar size, and element distributions); which is something I could certainly use. I'm sure, however, that these limitations will be addressed in future releases of the program, as users request them, so I recommend making the 40-something dollar investment for now.
As for a comparison between Universe Sandbox and Space Engine, if you want to simulate the "destruction" of planets by collisions with asteroids, other planets, black holes, and the like, then Universe Sandbox is for you. (I personally don't care too much for this aspect of the program.) Also, if you want to model the physical aspects of planetary orbits, the energy flow through their atmospheres and interiors, and tidal interactions of satellites, then choose Universe Sandbox. If, on the other hand, you want to merely simulate procedurally-generated images of planets, stars, and nebulae, including realistic surface maps, without needing to delve into the hardcore physics of your simulations, go with Space Engine. (Space Engine does have an atmosphere model, but I haven't examined it yet.)
I really hope that helps you decide. If you have the finances, I would buy both. Again, thanks for the comment.
Peter