If the earth had a second moon, could the moons ever cross? How and when?
May 30, 2012 2:12 PM Subscribe
Imagine that the earth is hit by another Mars-ish sized object causing a second moon to be formed. If the second moon were orbiting the Earth inside or outside of the orbit of The Moon, and assuming it was not orbiting the Earth parallel to The Moon, the two moons would have to cross each other at some point, right? A sort of moon-over-moon eclipse thing. How would you calculate how often this would occur? What would it look like? Does this happen on planets with more than one natural satellite? Does the premise of this question make no sense because my knowledge of astrophysics is basically nil? Explain to me like I am in fifth grade, please.
posted by Lutoslawski to science & nature (7 answers total) 2 users marked this as a favorite
As I understand it, the moon orbits around the earth where it does based on a common center of gravity. So if this second moon were to be larger or smaller, would the second moon be able to orbit inside or outside of The Moon's orbit?
If so, then could it orbit Earth on a plane that wasn't parallel to The Moon's orbit?
If both of those things happened, then ostensibly the moons would have cross each other at some point, right? Is there a name for this? How would you calculate how often/when this would occur?
If this happened, what would it look like? If the moon is reflecting light from the sun, would one moon crossing over the other just block out the light reflecting from the farther moon?
Are there any other weird things (like weird tidal things or the like) that would drastically change by having a second moon?
Does this not make any sense whatsoever because I've gotten some basic premise about gravity and mass and orbits mixed up?
Please explain to me like I don't know much about how the movements of celestial bodies work, because I don't.
Thank you Metafilter.