There are a number of forces that work on our solar system. If any of the forces were to change, life could be very different. For example, if the moon was gone there would be small tides and shorter days. Gravity is another force that acts on the moon and Earth. The gravitational interaction between the Earth and the moon create predictable tides and orbital rotation of the moon around the Earth. The Sun also affects the Earth. Solar wind from pushes high energy particles, which results in things like the Aurora Borealis.

These forces are only a small number that work on the solar system constantly.