I was just reading an article by Chronos from 30-Jan-2003 concerning the same side of the moon always facing the Earth. He links to another article that had been written in the past concerning how “tidal forces” work.
I know several of the planets in our solar system have more than one moon. Well, what if the Earth did? What sort of additional occurrences might we see? Bigger waves? Numerous high tides? No tide? Would we weigh less? A climate change? What else? I imagine it all might depend on the configuration of the moons around the Earth and the strength of the moons’ gravity etc. I’m no scientist, so you tell me.
What if we had two moons in a similar configuration to the moons of Mars? What if we had more? 5? 10? 39 (known) like Jupiter?
I’m no astronomer, but I do know that to answer your question, you have to answer at least the following two questions:
(1) What mass with Luna2 have?
(2) How far away is Luna2?
Mars’ two moons are really very, very small and probably have little effect on their parent planet. Likewise, Jupiter’s moons (compared to Jupiter) are very, very small. The only plenet that has a moon with a relative size to the parent even remotely close is Pluto (and Pluto’s moon is much larger than ours in terms of it’s relative size to it’s parent).
IANAS either but common sense should tell you that a second moon would definately slow down our planet. The second moon would pull on the earth and the earth would pull on it. Just as if our current moon dissappeared, the earth would spin faster. (And no, you will not travel through time). We would just have to run on a 25, 26, 27, 28, etc hour clock, instead of 24. Our day’s would last a lot longer. (Leave it up to corporations to make you work longer though).
Umm, Earth already has 2 moons (see the end of the article), you weren’t taught about Cruithne in school?
In addition, there are at least 2 objects that share the same orbit as the Earth and are occasionally drawn into orbit around us every once in great while.
Which leads me to the real point: given the huge relative mass of the Big Moon, it would be impossible for any other decent size moon to remain in stable orbit.
Blasphemy! Do you not note a particular posting style? (I had to abandon my 2-letter username when the board went through an updating, and the newer search engine wouldn’t search on usernames less than three or four letters.)
Anyway, the point I was making was that there is a size ratio between a planet and its moons, and the more moons a planet has, the smaller the moons have to be, or the farther out they have to orbit, else the system destabilizes and objects get thrown off one by one or collide until there’s only two objects left orbiting each other.
Another way to explain it is that objects only orbit in “sets” of two objects, and the next object out orbits around the center of mass of the inside “set”. And you can keep adding multiple objects and counting the previously added moons & planet as the inside set. So something like Jupiter can have a lot if little moons right next to each other, because the planet is huge, and the moons are for the most part influenced by the planet, and not very much by other moons…-but you cannot have [for example] another Earth moon located opposite the single moon Earth has now, because the mutual gravitational attraction of two moons and an earth would be much greater than one moon and the earth, so either the moons would have to be much smaller, or they’d have to be much farther out.
And either way, the tides on Earth would be smaller. Get it?
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Hmm… what if you have those 2 Earth moons orbiting the earth on opposite sides but much faster than the moon now orbits so that the centrifugal force on each moon is equal to the gravitational pull of the earth and second moon?
It is a metastable situation at best. Much like balancing a basketball ontop of another. The slightest whiff of air would cause it fall off. In the case of moons, the Sun would provide ample outside force. Once they got out of alignment, watch out. Very big crash. We’re talking about seconds to go out of alignment and just a few weeks before the bang occurs.
Stable orbital positions are at “Lagrange points”. Google yourself crazy on that term.
Correction: Equilibrium orbital positions are Lagrange points. In fact, the two-bodies-orbiting-opposite-each-other case is a Lagrange point situation. But only two of the five Lagrange points are stable.
Good question! There is a book on this very subject that explores what if the earth had no moon, two moons, and multiple moons (greater than two moons). I’ll see if I can locate it in my collection to share the exact title and author… - Jinx
I did not say that all Langrange points are stable. I said that ‘Stable orbital positions are at “Lagrange points”.’ Obviously I knew the distinction and made a correct statement.
