Virtually no activity on a moon will trigger an activity timer, including refreshing its Overview. This is another reason moons provide a strategic advantage. Because you can’t tap a moon in the Overview or Empire screen to view it directly, you must first go to that planet in Overview (which triggers an activity timer at that location), then tap the planet’s moon to view it. Once you are viewing the moon, no further actions there will indicate activity, and after 1 hour all activity timers there will disappear (see also Buildings > Jump Gate).