🌕 What if Earth had two moons?
Brighter nights, stronger and more complex tides.
The science
A second moon would add its own tidal pull. Depending on its orbit, tides could sometimes add up (spring tides on steroids) and sometimes cancel. Night skies would often show two lit discs at different phases.
Immediate consequences (modelled)
More complex tide cycles; brighter nights when both moons are up.
Possible long-term consequences (hypotheses)
Two moons can destabilise each other's orbits over millions of years; a collision or ejection is plausible in simulations.
Assumptions: Depends enormously on the second moon's mass, distance and orbital direction — no single answer exists.
Limitations: Does not model climate, geology, biology or engineering in full detail.
Reference: NASA / peer-reviewed planetary science