Definitely. Depending on where you put it, you’d either have a dramatic new mountain range (albeit one that will be settling for at least a few millenia) or a new continent. Also, you are (as previously noted) going to make the Earth somewhat lopsided, with resulting geophysical and perhaps rotational disturbances.
This sounds like the work of Jacques Laskar, a French astronomer. The only problem with it is that it is almost entirely unsubstantiated. A planet with a solid core might be more prone to large nutational disturbances given significant impulses (the only one in the Solar System would be Jupiter) or perhaps some kind of disruption in supposed orbital resonances between the inner worlds. The molten iron core of the Earth would tend to resist or dampen large rapid changes in rotational characteristic. However, without the Moon, the Earth would not undergo precession of the equinoxes.
A few other things to make note of: in order to slow the Moon down to land gently on the Earth you’re going to have to dissipate a heck of a lot of orbital (and a little bit of rotational) energy. Also, you’re going to alter the barycenter of the Earth-Luna system, resulting in some orbital discombobulation; the Earth is going to tend to bob back and forth across it’s normal orbital path. And you’re going to seriously ruin most of Paul McCartney’s post-Beatles ouerve, which in my opinion isn’t a bad thing but it will have a major economic impact on the British Isles, their other main export being, of course, jellied eels. (I kid, I kid.)
In general, this is just kind of a bad idea. Not as bad as turning Jupiter into a miniature black hole, but still doubleplusungood. How about a game of chess instead?
Until the two masses merge. The oceans should fill in the area between the two, and even with the displaced Pacific, the Atlantic could go way down as the water fills between the earth and moon. The atomospere would certainly get thinner. I don’t know if the moon would pull it all the way around it’s self, but it would draw some of it up above the Earth’s atmosphere.
The Moon won’t roll; it’ll split the crust and sink a bit into the Earth. Earthquakes and volcanos look like a hiccup compared to this; the Mid-Atlantic Rift will split like a grape from the shock. Until the Earth’s and the Moon’s masses collapse into each other, all the water and atmosphere will settle into the quasi-toroidal valley surrounding the junction. The land on the other side of the Earth - say, Africa and surrounding territories - will effectively be on a waterless mountain plateau jutting out of the atmosphere. This mountain won’t be nearly as high as the one formed by the Moon itself.
Life will have to gain a foothold again, after surviving the tumult. We’ll likely see ocean life first, once again, because the life-sustaining land surrounding the new ocean will be rather small due to its steep slope. There will be plenty of geothermal vents in the new ocean, and the surface will be in shadow most of the day (both from the moon and from a nuclear winter effect from all the volcanic activity), so life may start at the ocean floor.
On edit, I see Harmonious Discord beat me to the punch re: atmosphere and oceans resettling.
I imagine that eventually the pressure wave across the crust would cause the continental plates to do a little dance. Would continents change directions and start slamming into each other? If so, how long would that take?
Would there be any chance for anyone on the planet to survive this? I’m thinking about a handful that might happen to live on a chunk of land that is sufficiently close to stay inside the significant atmosphere, yet far enough away to avoid being melted into slag or torn apart by tidal forces.
It would make a great science fiction story, if you could figure out a plausible mechanism for a moon to hit the earth at a slow enough speed that the kinetic energy wouldn’t just turn the whole thing into a big mall of magma or blast the entire atmosphere away along with half the crust.
I assume we all know that the moon is made of cheese. Therefore, placing the moon on Earth would obviously give rise to the world’s largest wine and cheese extravaganza! I said extravaganza damnit!!
Seriously though, I think everything has been said already. Death of marine life in that area, rise of ocean levels, gravitational disturbance, and an extra deep Mariana trench (but only for 20 minutes).
I’m not even sure this can be done at all (barring teleportation.) Consider the Roche limit – you know, the one that would cause even over-large meteorites to break up on approach to Earth due to gravity pulling harder on their “near end” than on their “far end.” So, can this even be done, or is there (as I suspect) some point where the moon will be ripped apart by uneven gravitational pull (“Roche Limit Effect”)? How far out will it be when it disintegrates? What will be the effects of that? :eek:
Onw Scifi author wrote about two planets close to each other that transfered water and atmosphere sometimes. The expedition checking out one planet finds themselves on the other, with the mothership on the original planet, and them with a planetary exploring transport on the second. It was interesting, but I don’t know the book or author now. \
I know you said we could move the Moon gently, but you do have a massive object a long way away. :eek:
If you have the sort of technology that can bring the Moon here reasonably quickly and slow it down dramatically before impact , then you presumably have the technology to cope with all the problems mentioned above.
I beleive AWB is talking about the Earths crust.
Wouldn’t the moon just ‘sink’? Right through the crust. That’s what I think.
With the resulting additional internal mass of the earth creating incredible volcanoes and breaking up the earths crust/continental plates into much much smaller pieces with fissures in between.
The moon’s average density is about 3,350 kg/m³. The earth’s is about 5,500 kg/m³, 2,700 kg/m³ for the lithosphere. So the moon would probably just sink through to the asthenosphere.
Even assuming you could place it very gently, I think we’d be looking at the death of essentially all multicellular life on the planet. The other side of the Earth would likely be stripped of its atmosphere, and that’s without even getting into magnitude 30 earthquakes and volcanoes twice the height of Everest and the surface of the Earth basically being torn apart. There’s not a place on Earth that wouldn’t be ripped apart.
Rocheworld (Flight of the Dragonfly) By Robert L. Forward. The two planets there form a Double Planet, with the two components close enough to share an atmosphere. ISTR that the relationship was described in pretty minute mathematical detail in the book, and that somehow it worked out that the two planets were each outside the Roche Limit of the other – I don’t have the book handy, but this guy did some calculations on his own and comes up with the exact same configuration (note: I have no idea how correct his/her work is, but it should certainly give some of the more astronomically inclined Dopers some fodder to work on (if they choose to chime in))
and slow it down dramatically before impact 
, then you presumably have the technology to cope with all the problems mentioned above.
(if they choose to chime in))