Astromony questions dealing with setting details

The reason I'll asking the below questions deals with something else in the works but I dont want to clutter this thread with that topic but anyhow:<br /><br />In the original materials we were told details about the planets of the Frontier ie: the gravity of the planet and length of day<br /><br />What I was wondering for those of you up on astronomy and such what other details could be deduced from these facts? Sort of like math if x + y= z then what does knowing the gravity about a planet tell us about its density and diameter?<br /><br />In particular I was currious about if there was anyway to determine the length of a planet's year from the details we have? but other info is good too.<br /><br /><br />