What effects on Earth would we see if its orbital velocity was balanced with Jupiter's gravity at Moon distance to maintain a stable orbit? Assume everything is as it is now and we suddenly found Earth in that situation.

If Earth orbited  around Jupiter at the moon's present distance from Earth, then it would orbit Jupiter once every 1.43 days.  Assuming it starts with its present rotation rate, then Jupiter would cross the sky every 3.33 days.  However,  it would be undergoing nearly 27,000 times the tidal forces it does now, and this would likely drive a great deal of geological heating and tidal braking, and tidal locking would be the eventual outcome.  It wouldn't be a pleasant place to live.

4 hours ago, Janus said:

If Earth orbited  around Jupiter at the moon's present distance from Earth, then it would orbit Jupiter once every 1.43 days.  Assuming it starts with its present rotation rate, then Jupiter would cross the sky every 3.33 days.  However,  it would be undergoing nearly 27,000 times the tidal forces it does now, and this would likely drive a great deal of geological heating and tidal braking, and tidal locking would be the eventual outcome.  It wouldn't be a pleasant place to live.

Thanks Janus. It would be a highly kinetic environment; catastrophic weather patterns? What would we experience gravitationally in the short term and long term from the present status of things?

Edited October 9, 20241 yr by StringJunky

It's outside Jupiter's Roche limit, so we will remain a large moon and not break up into rings.  As Janus points out, the tidal forces would be incredible, and the heat generated from it would more than compensate for lack of sunlight.  The oceans I'm guessing would boil away as long as Earth's spin was there to generate the heat.  The earthquakes and volcanoes would probably be bad enough that you wouldn't much notice what the weather was trying to add to it.  No sun, but still plenty of heat to drive atmospheric convection, so yea, lots of wind but no rain. Nowhere safe to hide.

We'd be pretty close to the orbit of IO.  Enough for them to interfere?  IO is long since tide locked and doesn't get the geothermal tide heating that a spinning Earth would.

Just for fun, if you wanted the tidal influence to equal that now exerted by the Moon, you'd have to increase the orbit by a factor of 30, putting it somewhere in between the orbits of Himalia and Lysithea, with an orbital period of over 250 days.

However... ,

The cost of that extreme tidal-heating and voluminous volcanism would be a rapid slowdown in planetary rotation , with tide-lock occurring within 10-million years at most .

The lack of high-energy electromagnetic radiation would minimize atmospheric-stripping , this preventing the total removal of the displaced Earth’s oceans . These would soon freeze , as the tidal-heating and volcanism diminished .

The planet's atmosphere would however , slowly be removed by the particle-radiation driven process of "sputtering". A giant Europa would be the end result.

Edited July 4Jul 4 by Professor-M

🤓 Modification - An Earth situated very near Jupiter would be at the bottom of the greatest gravity-well in the outer solar-system . This draws in a steady and heavy influx of asteroidal and cometary materials, assuring that Earth’s atmosphere would be endlessly replenished .

The planet would freeze up soon after tide-lock , but it's atmosphere would remain . This iceball-Eatth would periodically build up an excess of carbon-dioxide from volcanic activity , this resulting in relatively short interludes of global warm-up from the "greenhouse-effect" . Abundant surface water and plate-tectonics would inevitably combine to sequester said CO2 , returning the planet to iceball status fairly quickly , by geological standards .

*. The below Reference addresses the likely atmospheric cycle should Jupiter's radiation-belts prove capable of stripping off much of Earth’s atmosphere .

https://photos.app.goo.gl/sBj1Wyu4Jwrh7cLJ8

Edited August 15Aug 15 by Professor-M
Addendum

On 7/4/2025 at 5:31 PM, Professor-M said:

The cost of that extreme tidal-heating and voluminous volcanism would be a rapid slowdown in planetary rotation , with tide-lock occurring within 10-million years at most .

I assume* you have a calculation or reference that backs this up.

*I actually think you don’t. Bullshitting is not tolerated well ‘round these parts.

🧐 I don't bullshit , I estimate or calculate . Also , using various search-engines yields only descriptions of the subject process which have less math in them than mine displayed up above . In otherwords , the involved variables make it impossible to produce a credible figure here , only the below process descriptions and numerical approximations are possible in this case .

If we use Mr. Janus' figure of 27,000 times Luna's tidal-effect on Earth , then multiply that figure by a factor of 50 due to the mass increase likely needed to gestate an Earth-class moon around a Jupiter , then we get a sum-total of 135,000 times the tidal slow-down rate induced by Luna . Since that slow-down currently sits at ~1.7millisecond a century , the Question's moon could be expected to be slowing at about 46-seconds a century , or 46k.sec. per millennium .

Even if we presume some sort of capture scenario whereby an Earth is placed in close orbit to Jupiter , then we calculate a slow-down rate of 46k.sec. per 50-millenia .

The above means that the subject planet would theoretically cease rotating in under two-thousand years , one-hundred thousand if the host-planet is only one Jupiter-mass .

Realistically , slow-down would be faster early on , and slower later on . This means that the above estimate could be off quite a bit , BUT even then , would still be nowheres near the initial estimate of ten-million years .

https://www.discovermagazine.com/the-earths-rotation-is-gradually-slowing-down-42310

*Now then , considering that the above Question simply seeks descriptions of the processes and consequences of having an Earth in close orbit around a Jupiter (full-mass or other) , and that NONE of the other writers came close to engaging in making the number of descriptive calculations that were demanded of me , I must ask why only I have to write a numerical treatise where they obviously do not . 🧐

Edited August 18Aug 18 by Professor-M

40 minutes ago, Professor-M said:

I don't bullshit , I estimate or calculate . Also , using various search-engines yields only descriptions of the subject process which have less math in them than mine displayed up above

You had no math, so they use less than that?

40 minutes ago, Professor-M said:

If we use Mr. Janus' figure of 27,000 times Luna's tidal-effect on Earth , then multiply that figure by a factor of 50 due to the mass increase likely needed to gestate an Earth-class moon around a Jupiter

The 27,000 number was for “If Earth orbited  around Jupiter at the moon's present distance from Earth”

What does “an Earth-class moon around a Jupiter” (and this factor of 50) have to do with this? It’s earth around Jupiter. No modifications.

46-seconds a century , or 46k.sec. per millennium .

A century is still 100 years, right? A millennium is 10x longer? How do you get from 46 to 46k?

It's a set of parameters , one the literal but unlikely scenario , the second the much more realistic one .

The 46-seconds a century obviously is the former, equating to seize-up in 78 centuries. The latter should be 2300 , equating to just over 1.57 centuries . So almost 8k. years and under 1.57 centuries ; both well under ten-million , as originally stated .

I will allow for a dropped decimal point in the original calculations , caused apparently by profound physical exhaustion and late-night in-the-head calculating .

I am sure you can identify with this , right ? 😵

*Very busy ; refining right now .

Edited August 18Aug 18 by Professor-M

First off the view would be AMAZING! Imagine looking up at the night sky and seeing Jupiter appearing about 25 to 35 times or so larger than our moon. It would take up most of the sky. Unfortunately we most likely wouldn't be able to see other stars with the naked eye anymore. Also intelligent life would most likely end due to many factors.

Lots of changes would occur on Earth including:

• Violent tides would wreck havoc.

• Our atmosphere would either be stripped away or radically change.

• If Earth doesn't orbit Jupiter in approximately two days it would be too slow and eventually be sucked in.

• There's a chance Earth would collide with Io.

• Earth could be exposed to massive radiation from Jupiter.

• Oceans would likely eventually freeze.

• Earth's temperature would definitely drop, possibly up to 100 to 200 degrees Fahrenheit.

• Extreme seismic activity in the form of volcanoes and earthquakes would dominate.

• Earth would likely become tidally locked creating vast temperature differences.