# Is Jupiter's magnetic field the largest object in the solar system? **URL:** \ **Category:** Factual Questions\ **Created:** [April 18, 2024, 4:44pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464 "2024-04-18T16:44:47Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Dr.Winston\_OBoogie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.winston_oboogie/32/2945_2.png) [@Dr.Winston\_OBoogie](https://boards.straightdope.com/u/Dr.Winston_OBoogie)\ **Post date:** [April 18, 2024, 4:44pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/1 "2024-04-18T16:44:47Z")
Someone at my work sends out daily “fun facts”. Most of them are useless trivia. Today, there was one that said > [@](#): > > Jupiter’s magnetic field is the single largest object in the Solar System. If it were visible to the naked eye, it would appear larger than the Sun or the Moon. My first thought was “what about the Sun’s magnetic field? Wouldn’t that be larger?” My second thought was “if we’re talking about “area of influence” as opposed to specific material object, wouldn’t the Sun’s gravitational field count?” Any comment from people who actually understand and are knowledgeable in physics? ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [April 18, 2024, 4:52pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/2 "2024-04-18T16:52:23Z")
> [@Dr.Winston\_OBoogie](#): > > My first thought was “what about the Sun’s magnetic field? Wouldn’t that be larger? Yes, it is. But it’s not “in the solar system.” It’s bigger than the solar system. ---
**Author:** ![Dr.Winston\_OBoogie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.winston_oboogie/32/2945_2.png) [@Dr.Winston\_OBoogie](https://boards.straightdope.com/u/Dr.Winston_OBoogie)\ **Post date:** [April 18, 2024, 5:28pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/3 "2024-04-18T17:28:32Z")
Doesn’t the influence of SOL it kinda DEFINE the SOLar System? ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [April 18, 2024, 5:36pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/4 "2024-04-18T17:36:16Z")
Wouldn’t the heliosphere be larger than (the commonly accepted practical limit of) Jupiter’s magnetic field? And pretty much defines by itself what is ‘in’ the solar system or not? ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [April 18, 2024, 5:59pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/5 "2024-04-18T17:59:10Z")
I vote for the Oort Cloud. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 18, 2024, 6:20pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/6 "2024-04-18T18:20:51Z")
It sounds to me like the factoid is about the apparent visual size, i.e. the angular diameter, of the thing as seen from Earth. By that sorta convoluted standard, if we could see magnetic fields, the “circular cloud” of magnetism surrounding the pinpoint of light that is Jupiter would look bigger to us in the sky than the Sun or the Moon do. And from our POV, the Sun’s magnetic field would just look like “the entire sky in every direction”. In another convoluted sense, something visible everywhere is sorta just the background and so is nowhere visible as a foreground object. So it “doesn’t count” for these purposes. This is all the sorts of reasoning an 8th grader would use to make a funny or tricky comment. It’s certainly not a seriously scientific POV despite being based wholly on facts, not made-up nonsense. IOW, bog-standard illiterate gee-whiz listicle fare. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [April 18, 2024, 6:22pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/7 "2024-04-18T18:22:00Z")
> [@Dr.Winston\_OBoogie](#): > > Doesn’t the influence of SOL it kinda DEFINE the SOLar System? Nope! The solar system is the sun, plus planets & asteroids that orbit the sun, plus things that orbit those things. The sun’s magnetic field is bigger than that. I agree that it’s trick wording, because Jupiter’s magnetic field isn’t really an “object”. If all the magnetic fields of all the planets were visible, Jupiter’s would indeed be larger than any object you could see in the solar system. If the sun’s magnetic field were visible, it would be all you could see in every direction. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [April 18, 2024, 6:22pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/8 "2024-04-18T18:22:21Z")
> [@Napier](#): > > I vote for the Oort Cloud The factoid said “largest _single_ object”, and the Oort Cloud is composed of many objects (trillions, I understand). So that’s right out as are the Asteroid and Kuiper Belts. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [April 18, 2024, 6:29pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/9 "2024-04-18T18:29:02Z")
> [@HMS\_Irruncible](#): > > The solar system is the sun, plus planets & asteroids that orbit the sun, plus things that orbit those things. The sun’s magnetic field is bigger than that. Objects orbiting the Sun go out about a light year, perhaps more. Is that more or less than how far the Sun’s magnetic field extends? I don’t know how far the latter extends, but probably not further than the Heliopause. Which is no where near a light year out. ---
**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:** [April 18, 2024, 7:07pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/10 "2024-04-18T19:07:16Z")
Just as with gravitational fields, there is no specific distance to where you can say a magnetic field ‘ends’. The strength of the field drops as roughly a cubic inverse (complicated by the fact that all magnetic fields are dipoles and the shape is effected by the dipole moment). Effectively, the Sun’s magnetic field ‘ends’ where the background magnetic field of the galaxy is more dominant, but both are so low that it would be difficult to define a specific boundary and would be constantly in flux anyway. Similiarly, Jupiter’s magnetic field essentially terminates where the Sun’s magnetic field has a stronger effect. Stranger ---
**Author:** ![Saint\_Cad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saint_cad/32/18907_2.png) [@Saint\_Cad](https://boards.straightdope.com/u/Saint_Cad)\ **Post date:** [April 18, 2024, 7:10pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/11 "2024-04-18T19:10:28Z")
I’m calling [BS](https://nationalmaglab.org/magnet-academy/history-of-electricity-magnetism/places/magnetic-field-of-sun/#:~:text=Similar%20to%20our%20own%20planet,planet%20in%20the%20solar%20system.) on the factoid > Similar to our own planet, the sun is like a huge bar magnet with a north and a south pole producing a magnetic field. But the sun’s magnetic field is about twice as strong as the Earth’s and much, much larger, **extending well beyond the farthest planet in the solar system**. ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [April 19, 2024, 11:59pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/12 "2024-04-19T23:59:25Z")
I’m late to the party, but, yeah, that factoid is ill-defined at best, but that’s too charitable. - There’s no coherent way to define the physical size of the field.\* - Even in the presence of other, possibly stronger, magnetic fields, Jupiter’s field is still exerting its influence. If I put a pebble on a scale, and then you add a bowling ball to the scale, the pebble’s still there, even though the scale is reading a number that’s dominated by the bowling ball. - If talking about a magnetic field’s size did make sense, then, yes, gravitational fields should be fair game, too. - The factoid’s conceit “If it were visible to the naked eye…” could be applied to other aspects of an objects’ electromagnetic influence. The most salient influence is due to the copious visible and infrared photons being emitted (via reflection, blackbody radiation, etc.) If the sphere of influence of that electromagnetic output were “visible to the naked eye”, it would be physically large too (also without an end). - Gravitational waves are big objects. How about those? \*Unhelpful footnote, for fun: Jupiter as a distinct item didn’t exist prior to circa 4.6 billion years ago, and so there couldn’t have been a field from Jupiter before that, and so Jupiter’s field definitely can be no larger than 4.6 billion lightyears in size since it’s influence can propagate no faster than the speed of light. ---
**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:** [April 20, 2024, 1:24pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/13 "2024-04-20T13:24:59Z")
Don’t forget - If one did, in any way, define the “size of a field” (whether gravitational or magnetic), and defined “object” in such a way that a field qualified, then the field of the Sun would always be larger than the field of Jupiter. Oh, and while we’re at it with astronomical fields as “things”, the magnetic field of a neutron star can be millions of times denser than lead. Not the matter of the star itself; just the magnetic field. ---
**Author:** ![ASL\_v2.0](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asl_v2.0/32/3525_2.png) [@ASL\_v2.0](https://boards.straightdope.com/u/ASL_v2.0)\ **Post date:** [April 20, 2024, 1:40pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/14 "2024-04-20T13:40:49Z")
I still object to a magnetic field of any kind being called an object. Certainly not under the most common lay definition of the term, as objects are supposed to be material things. A magnetic field is not itself material. Is there some commonly accepted scientific definition of object that encompasses magnetic fields? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 20, 2024, 3:57pm UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/15 "2024-04-20T15:57:39Z")
> [@Chronos](#): > > Oh, and while we’re at it with astronomical fields as “things”, the magnetic field of a neutron star can be millions of times denser than lead. Not the matter of the star itself; just the magnetic field. Holy crap! I had never thought about that stuff in that way. Mind blown, duude! ---
**Author:** ![Saffer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saffer/32/6440_2.png) [@Saffer](https://boards.straightdope.com/u/Saffer)\ **Post date:** [April 24, 2024, 8:00am UTC](https://boards.straightdope.com/t/is-jupiters-magnetic-field-the-largest-object-in-the-solar-system/1000464/16 "2024-04-24T08:00:38Z")
> [@dtilque](#): > > The factoid said “largest _single_ object”, and the Oort Cloud is composed of many objects (trillions, I understand). So that’s right out as are the Asteroid and Kuiper Belts. The only objects that aren’t composed of many objects are elementary particles, and those are very small indeed.