After selecting a planet or starbase, hit the "D" key. You don't need to have done any espionage to see detailed info on either.
For planets you can see the bonus percentages from buildings on that planet.
For starbases you'll see everything that has been constructed on it.
There is an added bug with the planet details screen. If you hit the Done button in the lower right then it will mess up the main game window. Fortunately hitting F1, F2 or such will clear the problem.
