Question:
I have a question of a more fantastical nature. For a bit of context I’m writing a homebrew Dungeons & Dragons world and currently working on the calendar. I was wondering what would the effects of having two moons have on the land and world as a whole? If possible for you to explain what would a calendar look like for such a world?
Answer:
1. Tides and Ocean Dynamics
With two moons, tides would be more complex. On Earth, the gravitational pull of our single moon creates predictable high and low tides. Adding a second moon would create an interplay of gravitational forces that could result in:
- Multiple tidal cycles: Depending on the relative masses and distances of the two moons, there could be overlapping tides of varying strengths. This might result in extremely high “spring” tides when both moons align or unusual tidal behavior when they are out of sync.
- Increased tidal variability: Coastal areas might experience unpredictable or very high tidal ranges, potentially reshaping shorelines and affecting local marine ecosystems.
2. Climate and Weather Patterns
The gravitational effects of two moons could impact atmospheric circulation:
- Stronger tidal forces could lead to variations in the atmosphere, potentially influencing wind patterns, pressure, and precipitation. This could create weather phenomena tied to the phases of each moon.
- Periodic climate shifts: Depending on the orbital paths of the moons, the combination of their gravitational pulls could contribute to longer cycles of climate change, similar to Earth’s Milankovitch cycles, but on potentially shorter timescales.
3. Geological Effects
- Tectonic activity: The stress from two sources of tidal forces might increase volcanic and seismic activity. This could shape world-building aspects of your D&D campaign, such as regions known for frequent earthquakes or active volcanoes.
- Erosion and landforms: Over millennia, the fluctuating tidal forces could create unique landforms shaped by alternating high and low water cycles.
4. Calendar Systems
Designing a calendar with two moons would require considering their orbital periods. For example:
- Phases and eclipses: With two moons, there would be more frequent lunar eclipses or potentially even double eclipses, where both moons align with the sun at different times. The phases of each moon would be independent unless their orbits are synchronized.
- Dual lunar months: You might have one moon with a shorter orbital period (e.g., 15 days) and another with a longer one (e.g., 30 days). This could create overlapping cycles where certain dates mark both moons being full, new, or at quarters.
- Cultural significance: The alignment of the two moons could be used as special holidays, omens, or seasonal markers. The calendar could be divided based on the phases of both moons, with certain days or weeks designated as festivals or important events when both moons are full or new.
Sample Calendar Concept:
- Month structure: If one moon takes 15 days to complete its orbit and another takes 30 days, a single month could be 30 days long with alternating weeks where one moon is full or new.
- Week design: You might create two parallel weekly structures, one corresponding to the cycles of each moon.
- Lunar events: A calendar could highlight double full moons, which might occur every 60 days (the least common multiple of 15 and 30 days), as major cultural or supernatural events.
These elements could serve as storytelling tools in your D&D world, adding depth to the lore, religion, and daily life of its inhabitants. And the best part? It’s YOUR world – it doesn’t have to follow our universe’s physics!
