Quote Originally Posted by Oneironaut
... but the other planets' effects on the tides are not measurable. If they can't even manage to cause a slight variation in the tides, it's certain that they won't be able to cause any natural disasters.
Ha I acually had to do this as a homework problem in my ast 2001 class. The tidal effects of all the other planets combined have almost no effect compaired to the sun and moon. You can derive the tidal force from newtons second law: Tidal force=2GMm/r^3.

Compair Jupiter and the Moon (because of it's mass Jupiter will have the greatest tidal effect on the Earth after the Sun)

Jupiter~7.47x10^9
Moon~1.22x10^15

This means that Jupiter has 0.000006 of the tidal effect on the Earth as the moon. The Sun has somthing like 0.26 of the tidal effect as the moon.

I'll have to find my old homework and find out what I acually did. But it's basicly done this way for each planet, then you sum up all the forces.