# Jovian Gravity **URL:** \ **Category:** Factual Questions\ **Created:** [March 29, 2019, 11:42am UTC](https://boards.straightdope.com/t/jovian-gravity/831709 "2019-03-29T11:42:05Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [March 29, 2019, 11:42am UTC](https://boards.straightdope.com/t/jovian-gravity/831709/1 "2019-03-29T11:42:05Z")
So how close can one get to Jupiter before the gravity exceeds 1G? Inside the atmosphere? ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [March 29, 2019, 12:35pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/2 "2019-03-29T12:35:34Z")
Should be the square root of the ratio of Jupiter’s Mass over Earth’s mass multiplied by the radius of earth --\> 1.6r[sub]jupiter[/sub] (112,313 km). That’s about the distance Amalthea orbits. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 29, 2019, 1:36pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/3 "2019-03-29T13:36:15Z")
Of course, if you’re “getting close to” Jupiter, you’re probably doing it along some orbit, which makes the local acceleration due to gravity mostly irrelevant for passengers aboard the spaceship. For comparison, Earth’s gravity is still about 85% of its surface value, at the height of the International Space Station. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [March 29, 2019, 1:51pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/4 "2019-03-29T13:51:34Z")
> [@Chronos](#): > > Of course, if you’re “getting close to” Jupiter, you’re probably doing it along some orbit, which makes the local acceleration due to gravity mostly irrelevant for passengers aboard the spaceship. For comparison, Earth’s gravity is still about 85% of its surface value, at the height of the International Space Station. Well that or freefall into Jupiter, but again unless in the atmosphere the passengers are not going to feel the gravity. ---
**Author:** ![Shodan](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@Shodan](https://boards.straightdope.com/u/Shodan)\ **Post date:** [March 29, 2019, 2:16pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/5 "2019-03-29T14:16:59Z")
I don’t know if the right term is “hovering” or the Jovian equivalent of geosynchronous orbit, but assuming you are stationary or nearly so relative to Jupiter’s center of mass. I.e. not in free fall. Regards, Shodan ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 29, 2019, 2:18pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/6 "2019-03-29T14:18:51Z")
Freefall directly in is a kind of orbit. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [March 29, 2019, 3:00pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/7 "2019-03-29T15:00:42Z")
> [@Hypno-Toad](#): > > So how close can one get to Jupiter before the gravity exceeds 1G? Inside the atmosphere? IIRC at the top of Jupiter’s atmosphere (however they define something without a definite edge) the “surface” gravity is around 2.5G. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 29, 2019, 3:54pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/8 "2019-03-29T15:54:24Z")
Basically, the “surface” is what looks like the surface. The same standard is used for stars. And for anyone wondering how it can be so low, gravity depends not just on mass, but radius, and Jupiter’s radius is a lot bigger than Earth’s. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [March 29, 2019, 4:03pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/9 "2019-03-29T16:03:35Z")
> [@Chronos](#): > > Basically, the “surface” is what looks like the surface. The same standard is used for stars. But it wouldn’t look like “the surface” if you were at it. > [@](#): > > And for anyone wondering how it can be so low, gravity depends not just on mass, but radius, and Jupiter’s radius is a lot bigger than Earth’s. And Jupiter is less than a quarter the density of Earth. ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [March 29, 2019, 6:16pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/10 "2019-03-29T18:16:41Z")
> [@Darren\_Garrison](#): > > IIRC at the top of Jupiter’s atmosphere (however they define something without a definite edge) the “surface” gravity is around 2.5G. So the sci-fi stories I’ve read of folks using airships to live in Jupiter’s atmosphere is not possible? Unless those folks are OK with 2.5 Gs? ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [March 29, 2019, 6:39pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/11 "2019-03-29T18:39:52Z")
I think you should be more concerned about being crushed by Jupiter’s atmospheric pressure than dealing with its gravity. > [@](#): > > Temperatures rise to approximately 1,340 F (725 C) at heights of over 600 miles (1,000 km). A third of the way into the planet, the hydrogen in the atmosphere becomes metallic, allowing it to conduct electricity. This helps to drive Jupiter’s powerful magnetic field. The planet rotates rapidly — once every 9.9 hours — and the rapid spinning causes electrical currents in the metallic hydrogen to generate electricity that powers the planet’s magnetic field. Jupiter’s magnetic field is almost 20,000 times as powerful as Earth. I think a close, very rapid orbit just outside its atmosphere would be your best bet for safe exploration. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 29, 2019, 7:33pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/12 "2019-03-29T19:33:19Z")
> [@Jasmine](#): > > I think a close, very rapid orbit just outside its atmosphere would be your best bet for safe exploration. What about all the lethal radiation? Surely hanging around Jupiter can’t be that good for your health. ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [March 29, 2019, 7:43pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/13 "2019-03-29T19:43:18Z")
> [@DPRK](#): > > What about all the lethal radiation? Surely hanging around Jupiter can’t be that good for your health. Good call. You’d have to be outside its magnetosphere which, according to the specs, extends something like 3,000,000 KMs into space. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 29, 2019, 8:28pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/14 "2019-03-29T20:28:33Z")
> [@Shodan](#): > > I don’t know if the right term is “hovering” or the Jovian equivalent of geosynchronous orbit, but assuming you are stationary or nearly so relative to Jupiter’s center of mass. I.e. not in free fall. A satellite in _geostationary_ orbit remains in position above a fixed point on the equator of the Earth in a circular orbit. A _synchronous_ orbit is one that has an orbital period which is the same as the rotation rate of the body, and thus, passes over the same point each day; a stationary orbit can be considered the trival case of the synchronous orbit. Since Jupiter does not have a solid crust the rotation rate varies with latitude and depth but equator of Jupiter rotates in about a 10 hour period, so a stationary-like orbit would be very fast and low, a scant 19,200 km above the surface. An orbit, by the way, is “free fall” by definition; that being that only gravity is operating on an object. In the case of a stable orbit, the object is falling so fast that it literally falls above the horizon. That it appears stationary in an observer’s frame of reference is irrelevent; what matters is that it follows a geodesic curve that makes a closed, non-intersecting path around the object. > [@Hypno-Toad](#): > > So the sci-fi stories I’ve read of folks using airships to live in Jupiter’s atmosphere is not possible? Unless those folks are OK with 2.5 Gs? There are many reasons why it would not be desireable to live in or around Jupiter, including the charged particle environment, high magnetosphere, charged plasma from Io spraying everywhere, and having to see a giant staring red eye (or anus, depending on how you think of it) every time you look through a viewing portal. Basically, Jupiter is the Jersey Shore of planets. Saturn has rings, better moons (including the only moon with a significant atmosphere and surface hydrocarbons), and is generally just a better neighborhood to hang around in. It is almost twice as far from Earth orbit at Jupiter, but if you’re going out that far into the black anyway, you might as well make the destination worth the effort. Stranger ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [March 29, 2019, 8:37pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/15 "2019-03-29T20:37:40Z")
Heavy, man. Check out the 1942 Isaac Asimov short story “Victory Unintentional” for an interesting - and funny - look at a robotic mission to Jupiter. ---
**Author:** ![Reindeer\_Flotilla](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reindeer_flotilla/32/3024_2.png) [@Reindeer\_Flotilla](https://boards.straightdope.com/u/Reindeer_Flotilla)\ **Post date:** [March 29, 2019, 8:51pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/16 "2019-03-29T20:51:34Z")
> [@Stranger\_On\_A\_Train](#): > > …, charged plasma from Io spraying everywhere, … I’m so adding Io to the list of Jovian moons I’m not attempting. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [March 29, 2019, 9:26pm UTC](https://boards.straightdope.com/t/jovian-gravity/831709/17 "2019-03-29T21:26:46Z")
> [@Hypno-Toad](#): > > So the sci-fi stories I’ve read of folks using airships to live in Jupiter’s atmosphere is not possible? Unless those folks are OK with 2.5 Gs? There is some depth within Jupiter where the gravity is 1G, because the gravity of the mass above cancels out the gravity of the mass below, but I don’t know what depth that would be, and if it is before the “real” surface below the clouds, but wherever it is, it would not be a pleasant neighborhood. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 30, 2019, 1:32am UTC](https://boards.straightdope.com/t/jovian-gravity/831709/18 "2019-03-30T01:32:14Z")
Nobody knows of any “real surface” within Jupiter. There probably is one, but it’d be pretty deep down. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [March 30, 2019, 1:37am UTC](https://boards.straightdope.com/t/jovian-gravity/831709/19 "2019-03-30T01:37:08Z")
> [@Chronos](#): > > Nobody knows of any “real surface” within Jupiter. There probably is one, but it’d be pretty deep down. Any chance of it being liquid? ---
**Author:** ![Telperion](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telperion/32/509_2.png) [@Telperion](https://boards.straightdope.com/u/Telperion)\ **Post date:** [March 30, 2019, 1:43am UTC](https://boards.straightdope.com/t/jovian-gravity/831709/20 "2019-03-30T01:43:02Z")
> [@kanicbird](#): > > Any chance of it being liquid? There’s probably liquid hydrogen. [Next page](https://boards.straightdope.com/t/jovian-gravity/831709.md?page=2)