Osmos is a fantastic game based around the concept of planetary orbits, and set in a relaxing ambient space environment. I highly recommend you try it when you're in the mood for a chill activity.
The gist is that self-organized molecules (ie: life) will build themselves in a single chirality (organic molecules can exist in two mirror images, chirality is the term to distinguish them; think your right and left hands). Light that reflects from organics will contain a tell-tale signature (polarization) depending on the chirality. This could be used to detect evidence of "life" on other planets. Clever.