Astrophysics is an area of science, where it is impossible to set up experiments due to the enormous spatial and temporal scales involved. We can either try to observe what is already there or use our knowledge of physics to calculate how the heavens should behave. Programming computers to solve physical equations and giving it a starting point, allows us to predict how planets and stars will behave millions and billions of years into the future. Actual scientific simulations are often quite complex, require a lot of computational power and are hard to grasp without the years of specialized study. Fortunately for the amateur astrophysicists, Universe Sandbox 2 gives an opportunity to simulate a wide variety of astronomical events in a much more accessible way.

The main (and the oldest) feature of Universe Sandbox 2 is the simulation of Newtonian gravity. These laws discovered over 300 years ago are good enough to describe most normal astronomical interactions with decent precision, as long as you can properly calculate the results. Unfortunately, the amount of calculations increases exponentially, as you add more bodies to simulate. US2 tries to configure simulation settings on the fly for the optimal experience, but do not expect to accurately predict how 2 thousand mutually interacting planets will look 2 million years into the future. As long as you’re not too needy, there are many interesting smaller systems that can be simulated much faster. There are also has non-attracting particles to simulate thousands of particles to produce beautiful dust clouds and planetary rings.

While the long distance gravitational interactions can be quite interesting and unusual, the close encounters bring a lot of visual excitement. Even a close approach without hitting each other may rip one of the objects apart due to the tidal forces. The resulting fragments may then lead to smaller impacts and form a ring, with collisions being quite detailed since the latest versions. While a slow tiny rock might be gone in a short flash, the more energetic impacts produce lasting marks with surface shockwaves, as well as the additional dust and debris. Launch the Moon into Earth and you will get an impact of planetary scale, leaving the planet with molten lava surface and large rocks thrown into orbits around it. Unfortunately the developers have not yet managed to implement the most accurate model of such encounters in the game. However, as development continues, we should expect more accurate and detailed modelling of these interactions.

In addition to gravitational simulations, Universal Sandbox 2 also has the ability to simulate the magnetic fields of celestial bodies and the climates on the planets. With these, it is possible to see the shape of a planet’s magnetic field under the stellar wind and see the jets emitted from pulsars. Climate simulations show how the atmospheric composition and the planet’s orbit change the conditions on it over long timescales. While there are many parameters that can be manipulated when setting up simulation, game’s tutorials and collection of already made simulations make it quite easy to get grasp of. There are also some educational tutorials, showcasing modern scientific knowledge and rationale behind it. Developers have also update the game with the information gathered from the currently ongoing space research missions. Celestial body textures are updated based on the latest observations and some popular missions and interesting exoplanets can be viewed in the game.

Just setting up different systems and then doing nothing while they evolve might become boring. Fortunately, the game has “Sandbox” in its name for a reason. Simulations can be edited at any moment. Any object can be moved, its properties modified in an instant and simulation will continue based on these new conditions. There are tools encouraging such behaviour, giving an easy way to launch additional objects, particles or explode the existing ones in a single click.

Visually, US2 provides a very beautiful rendition of space. Planets and moons are textured either based on high resolution direct observations when available, or use artistic renditions of their surface. Hot surfaces shine based on their temperature and star surfaces have visible convection cells. The lighting on the celestial bodies produces very believable transitions between the bright and dark areas, while nearby objects cast shadows on the surface. The backgrounds can be changed either to make system feel like a part of a bigger galaxy or to remove all distractions. There is also an ability to take screenshots at higher resolutions and to record GIF video clips.

Overall, Universe Sandbox 2 is a somewhat unusual game. It is based on the real world physics and simply allows players to see how different scenarios would develop. While not everybody would enjoy playing it, US2 is also a very nice educational tool.