# What would happen if Jupiter and Earth were at the same distance as the Moon is from Earth?

If Spock came with a super machine capable of moving planets, and placed Earth so close to Jupiter as the Earth's moon, the gravity of Jupiter would make us fall into it?

• To sum up Gerald's answer, we would be doomed. – Cheeku Apr 8 '14 at 1:15
• This belongs to Science Fiction, not to a serious SE site. – ott-- Jul 16 '16 at 19:25
• @ott-- On the contrary, this question is about the astrophysical effects of a counterfactual. It's perfectly fine here. – Sir Cumference Jul 16 '16 at 21:50

That's no good idea. Earth wouldn't necessarily fall into Jupiter in the short run, provided it orbits Jupiter fast enough (within about 1.7 days), and on a circular orbit, but we would risk to collide with Io, destroy it by tidal forces, or change its orbit heavily. The other Galilean moons would get out of sync and change their orbits over time.

Tides would be severe on Earth, not just limited to oceans, but also for "solid" ground, as long as Earth isn't tidally locked. This would result in severe earth quakes and volcanism.

Our days would be dim due to the distance to the sun. After tidal locking of Earth and ejection/destruction of Io the tides as heat source would be lost, oceans would freeze, temperature would fall to about -160°C mean temperature. During the polar night oxygen would probably condense from the atmosphere and form lakes, may be even nitrogen. By this atmospheric pressure would drop.

Since Spock is smart enough to know these consequences in advance, he wouldn't do it.

• Some, but not all, of the bad effects could be alleviated by changing the conditions a bit: Move Jupiter into Earth's current orbit around the Sun, and put Earth into a circular orbit around Jupiter in tidally locked rotation. Once Earth's shape settles down from the new tidal forces, conditions shouldn't be too bad. Interactions with Jupiter's other moons might be a problem -- so move them. Interactions with Jupiter's magnetic field and radiation belts would still be, ahem, interesting. We should get some truly spectacular auroras, and we could see how Jupiter reacts to the extra heat. – Keith Thompson May 13 '15 at 0:06
• @KeithThompson Even with your improvements, I think (can't do the math to be sure), but 384,000 KM (are we doing distance from Surface or from Center - with Jupiter, that matters a lot), but that would be close to the liquid roche limit. Add the magnetic field and I think Earth would fairly quickly lose it's atmosphere and oceans, giving Jupiter a temporary, very pretty ring system, which solar heating and Jupiter's hot van Allen belt would make mince-meat out of fairly quickly, leaving the Earth a barren, dead, rock. Still not a great outcome for us, even with your adjustments. – userLTK Jul 16 '16 at 15:36
• I think it would be outside the Roche Limit at 384000 Km, as all four inner moons of Jupiter are closer than that (Metis, Adrastea, Amalthea and Thebe), and Amalthea (at least) is either ice or a rubble pile, since it has a density of around $0.9 g/cm^3$. EDIT: Just looked it up. Thebe is (officially) outside the fluid Roche limit, Amalthea inside (though somehow is holding together despite its composition). – AlaskaRon Jul 17 '16 at 23:02

The what if is superficial it could never exist, but if one were to imagine then; the out come would be very bleak for Earth and Mankind alike. Jupiter has the strongest gravitational pull of any planet in our solar system. It is one of our solar system's gas giants,or Jovian planets; most of it is made of metally hydrogen, the gas succumbs to the ultimate power of Jupiter's gravity, mass and temperature. It then turns from a gas to a liquid metal. These immense elements make it impossible for such an event to ever occur, but still cool to wonder about.

• What do you mean by "H3"? – Keith Thompson May 13 '15 at 0:01
• "Jupiter has the strongest gravitational pull ... most likely in our galaxy." Huh??? – ThePopMachine May 18 '15 at 18:42
• i will be changing my answer – jenni selman Jun 23 '16 at 2:55
• Jupiter's innermost core is probably made of similar elements as Earth, Iron, Nickle and other heavy elements. It might well have a metallic hydrogen core around that, but no H3 (if by that you mean Tritium). Tritium has a very short half-life and so there's essentially zero of it on or in any planets. – userLTK Jul 16 '16 at 15:21
• It’s symptomatic that an utterly clueless answer with a large unattributed picture maintains a positive score on this site. – Incnis Mrsi Sep 11 '16 at 17:21