You can use the time step menu:
You can set 1 sec = [time], and it'll fix the accuracy of the simulation so that each second in the program is one real second.
(One time step is the amount of time (in the program) between each time it calculates the position of all the objects in the simulation, so the more you increase it, the more inaccurate it gets.)
In this simulation, each time one second passes in the real world, 8.11 hours pass in the simulation.