# Effects on earth from a heavier moon

Hello.

I'm trying to write a book of fiction about a place where there is a moon much bigger than the one we have.

The mass is probabbly at least double the one we have here circling earth. It could probably be called a case of double planets.

My question is: How would the planet be affected.

I know that the tides would be more extreme, but how extreme?

What else would happen?

Last edited:

Related Other Physics Topics News on Phys.org
There is a lot that could happen if the moon was heavier:

- The best way to approach this problem is to consider an extreme scenario like Europa (a satellite of Jupiter's). Jupiter is really big compared to Europa. The eccentricity of its orbit causes Jupiter to distort Europa (by stretching it different amounts). This stretching is what scientists believe may be the cause for all the "cracks" on Europa's surface (you should check out a picture of Europa on google). Also, this stretching might cause heating within Europa melting its the ice beneath its surface (creating a subsurface ocean).

- In the case of the Earth, we can exhibit the same sort of thing (though to a lesser extent). A bigger moon will cause much bigger tides for sure, but now the Earth is constantly being stretched by different amounts (depending on the Moon's position in its orbit). So rather than seeing it only in the tides, we would likely have the Earth's core temperature increase thus increasing the average temperature of the Earth as a whole. Increasing the Earth's core temperature will definitely cause more seismic activity (more earthquakes of larger magnitude, volcanic eruptions, tsunamis, etc.).

- The effect might also be to cause the Earth's orbit around the Sun to be perturbed since the center of mass of the Earth-Moon system will be deflected (depending on how large we are saying the Moon will be).

- I can explain the real effect of the tides with mathematics and Newtonian physics if you would like. If there is anything else I can think of I'll get back to you.

Our disproportionately large nearby moon certainly gave Earth an early tidal nudge. But unlike Venus and Mars, our moon's gravitational influence also helped ensure that Earth's spin axis and climate remained stable over long timescales.
See Scientific America: Without the Moon, Would There Be Life on Earth?