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ChickenChimneyChanga t1_jb8ac8p wrote

Ganymede is the only known moon that has a magnetic field, and that is why it has been colonized, beltalowda


Jugales OP t1_jb8dbme wrote

You got it bosmang


JoeTheFingerer t1_jb8gh4f wrote

is there a minimum volume or mass required for a celestial body to have a magnetic field?


Hattix t1_jb8nsuc wrote

Yes, and it isn't constant over time.

A magnetic field comes from a conductive fluid core which generates electric currents via convection and the core's rotation, so the object needs to be large enough to have a dense, fluid core and maintain it over time.

In the very early solar system most larger objects (non-asteroidal) would have had fluid cores and so likely magnetic fields, but these cool over time for smaller objects and they lose the field. Ganymede's core is on the lower edge of what could retain a magnetic field until the present day.

Coupled with differences based on core composition, we therefore believe Ganymede's core to be slightly larger than Mars'.


gryfter_13 t1_jb9lpez wrote

Don't tidal forces also play a role in keeping Ganymede's core liquid? Or is that Io's volcanic activity?


MrLucky13 t1_jb9vexg wrote

I believe that's mostly Io. Isn't Ganymede the farthest of the big 4 from jupiter?


Hattix t1_jbav6rq wrote

Callisto is the outer moon. Tidal effects on Ganymede are smaller than the other two of the Laplace resonance, it's both the outer (and so slower) and the least eccentric (0.0011).

Callisto isn't part of that resonance.


Hattix t1_jbauvo9 wrote

Tidal effects from the other large moons (mostly Europa) would help, as would tides from Jupiter.

The Laplace resonance, however, dumps most of its excess energy into the inner moon, which orbits the fastest.


TeamWonderful7670 t1_jb9xiot wrote

I once saw an interactable documentary where Phobos was colonized and it opened the portal to hell.


PARANOIAH t1_jbbbud0 wrote

They had to send in a guy in a green suit to solve the issue.


dmr11 t1_jb9i5nu wrote

Jupiter emits a lot of radiation, so the surface of this moon is still not completely safe despite the magnetic field:

> The radiation level at the surface of Ganymede is considerably lower than at Europa, being 50–80 mSv (5–8 rem) per day, an amount that would cause severe illness or death in human beings exposed for two months.

Though considering how cold it is, a human would be wearing a suit anyways.


ChickenChimneyChanga t1_jb8a297 wrote

Mercury is actually twice as massive though as it is much more dense than Ganymede. Its core makes up 42% of its volume.

Nobody is as dense as the Earth though. We are fucking dense.


GriffinFlash t1_jb8ofy6 wrote

Wait a sec, I LIVE THERE!


Notoneusernameleft t1_jb9poqy wrote

Small universe…I live there. Do you know Bob? He lives there too.


critter2482 t1_jbabunc wrote

Hey there! It’s me, Teddy, from your planet.


Notoneusernameleft t1_jbbi0xa wrote

Oh Teddy, haven’t talked to you since that thing at that thing the other time. You still doing that stuff we talked about.

Also yes Earth is my planet…MY PLANET!


mattttb t1_jb9fhey wrote

A big reason for Mercury’s core being so big compared to its total volume is that the outer layers of the planet have been blasted by incredibly intense heat and radiation over billions of years.

Think how long the top soil of Earth would survive temperatures that swing between 420°C to -170°C from day to night, with unimaginable radiation at all times.


Penguigo t1_jba2jpg wrote

Correct me if I'm wrong, but isn't Mercury tidally locked, and therefore none of the planet experiences both day and night?


Gamenern t1_jba4zlq wrote

Mercury isn't tidally locked to the sun, but rather in a 3:2 spin-orbit resonance. It actually has a 'day' that is the same length as 2 'years'.


EmperorKira t1_jb97pbn wrote

We are 2 planets in 1


herbw t1_jbawpal wrote

Three if we count the vast and deep oceans. And then our thick atmosphere, where birds live, esp. Swallows, and many birds while migrating, too. 4 major layers is very complex system. Just right for life.


fish4096 t1_jb9972c wrote

gotta love our incredible core. Solid metal ball surrounded by flow of liquid metals, creating dynamo. forcefield a la Starcraft Immortals. Any stronger and vulcanic activity would make catastrophic events too frequent, preventing intelligent life to evolve.

any weaker and the solar radiation would be too strong on the surface, wrecking organics.


herbw t1_jbawbbk wrote

Neutron stars are tho. And cooling White dwarf stars as well.


TheVegabond101 t1_jba66i8 wrote

Who went on mercury to research all the points u r making ?.....srsly


ACoolKoala t1_jbaa4m2 wrote

"If we calculate Mercury's average density by taking its mass and dividing by its volume, we come up with a density of about 5430 kilograms per cubic meter."

Satellites probably and scientists on earth using the data for math.

You can figure out the volume and mass using satellites I assume since nobody has been to or on mercury.


TheVegabond101 t1_jbadlb0 wrote

All these are still mathematical guesses at the end then... 🤷‍♂️


ACoolKoala t1_jbaftd6 wrote,objects%20at%20distance%20r%20away.

This might be helpful to you but no it's pretty exact. NASA wouldn't be putting it out as a measurement if it wasn't exact. Also if you don't go through the math of it how do you personally know if it's a guess or not?

This is also from Quora somewhere: To calculate a planet's density, you will need to know its mass and volume. The density of a planet can be calculated using the formula:

Density = Mass / Volume

The mass of a planet can be determined through various methods, such as measuring the gravitational pull on nearby objects or by studying the orbits of its moons. The volume of a planet can be determined by measuring its size and shape, which can be done through observations or by studying the planet's gravity field. Once you have the mass and volume, you can plug them into the density formula to calculate the planet's density.

But also note that density of a planet can definitely change so exact meaning at this point in time.


TheVegabond101 t1_jbaxxt4 wrote

If u r not doing all this calculation without being present still be considered as theoretical. Not exact. Even no scientist can exactly explain the secrets of Pyramid building....let alone earth....and mercury.....just sayin


NouveauNewb t1_jbb4g4j wrote

You'd get more benefit from studying epistemology in a Philosophy 101 class rather than arguing the validity of the scientific method.


TheVegabond101 t1_jbb545u wrote

U don't know what u r talking i never argued validity of any method....i said its theoretical at the end of the day....not exact. Its your fault that ur brain interpret my message wrong. Now don't start Brain Vs Mind topic....cause it will be philosophy 101


NouveauNewb t1_jbb9fzq wrote

Science is theory. Seriously though, start with Descartes if college is out of reach. Becoming more well-rounded will help you prove your point because the way you say stuff now contradicts itself.


ACoolKoala t1_jbb9kxl wrote

Saying you as a human being have to physically be on the planet to measure the density of it is questioning the validity of the method we use to measure density of planets. We use accurate satellites and you deny their information as not accurate enough because a human being wasn't there. Do you see the logical fallacy in that? Do you realize we don't need physical human beings on the planet to do actual accurate science? Do you deny any of the info you learn from mars rovers because it wasn't gathered in person by a human being? Once again it's 2023 and that's not logical.


ACoolKoala t1_jbb8e01 wrote

Or math is more exact and it's not 1850 where we have to make theoretical guesses because we can send literal fucking probes and satellites to other planets to calculate the mass of a planet to an exact measurement. Theory in the context of science is not simply a guess—it is an explanation based on extensive and repeated experimentation.

You also don't need to be on the planet to calculate density if you bothered to read my last response. You clearly didn't. You can calculate the mass of a planet, standing on our planet, by looking at the gravitational effects on moons or other things around it. Notice how we live in 2023 and have sent satellites and probes to every planet in our system therefore don't need to make guesses as we've had decades to orbit them and measure with said satellites. You're being kinda anti intellectual with your reasoning right now.


TheVegabond101 t1_jbballl wrote

Anti intellectual...? I just said its all theoretical at the end of the my statement wrong ? No longer 5 to 6 decade ago...Scientist thought sun was its moving in orbit around milky way galaxy....that's fine example of one of your theory...Science is not absolute Truth....its constantly changing with discovery and technology...


ACoolKoala t1_jbbdvlv wrote

Yes your statement is wrong. Theoretical as a term in the science universe is more like a calculated measurement. Think about the Theory of Gravity. We can measure it, we can measure it's effect on matter in the universe. Do we know why it exists? How? Nope still a lot of science to do in that aspect that involves quantum mechanics, but we can still get VERY EXACT MEASUREMENTS of how it affects everything around us. From measuring the terminal velocity of your body flying through this planet to measuring the amount of pull our moon has on our planet (reasons tides exist). To the amount of pull Jupiters moons have on it (without ever physically visiting there aside from satellites).

These are all things people have studied and measured and pondered about for hundreds of years and we have technology to get continually more precise with those measurements. Hypothesis (scientific term for uneducated guess or question needing to be answered) don't get to be theory unless they are tested and proven rigorously nowadays.

Also that's the beauty of science is that it's allowed to change, and still be the closest thing we have to absolute truth. You should really delve into it sometime and that will make sense to you but nothing I have said to you is wrong.

Absolute truth is only something we can shoot for, and be happy with how close we get. It's not something you can sit here and weaponize against people who actually put the work in to give you a representation of the world around you that is measured and observed. If you dont put the work into learning about something, and doing the work to make theories or observations or measurements yourself, you kinda don't get the right to criticize.


TheVegabond101 t1_jbbfe4c wrote

Theory of Gravity. Our teacher used to taught us its pulling scientist say its pushing force...einstein happen.. I guess. My statement is not wrong....while i acknowledge that field of science is evolved to grt measures but still its not absolute or near to absolute Truth. We just discover another secret corridor in egyptian Pyramid even after having so many scientific tools. My statement still hold the truth....its just a theory....just like big bang....u can't prove it.


ACoolKoala t1_jbbgaak wrote

It is the closest thing to absolute truth that humanity will ever have and I'll leave this convo at that.

Going back in time to figure out the Egyptian pyramids is harder than measuring planets with satellites that don't change for hundreds to thousands of years. As well as I never said science has figured everything in the universe out. We have mapped more of our night skies than the oceans of our planet for example. The wonder of science is that there's always more to do and learn and find explanations for. None of what you said is a gotcha lmao. You're kinda just forcing your bias into this convo by going towards the big bang. The big bang is more provable than any religious beliefs around the world I'm sorry to say. Science is the method we will use to find explanations for everything in the universe if we ever get to ( I don't think we will since there's that many variables to our universe and humanity is limited to the time our species exists which is nothing on the scale of time in the universe).

Also yeah this is all just anti intellectual shit. Sorry. You are wrong. As much as these things can't be proven, people like you make even more unprovable claims. Prove to me that a deity created the universe. You can't aside from what your belief tells you. You can't prove that with absolute truth. Send a satellite to heaven and show me pictures of it if you're so confident. Like these are the kinds of things you're throwing out there. You are being disrespectful to people who put a lot more work into this shit than just making up stories about a sky figure creating the universe.

Reread this paragraph and internalize it..

Absolute truth is only something we can shoot for, and be happy with how close we get. It's not something you can sit here and weaponize against people who actually put the work in to give you a representation of the world around you that is measured and observed. If you dont put the work into learning about something, and doing the work to make theories or observations or measurements yourself, you kinda don't get the right to criticize.


TheVegabond101 t1_jbbhr6s wrote

Some Shitty Atheistic scientist theories that Universe came from nothing...!!! Biggest false claim ever. Nothing is conceptual term....just like means absent of everything...i.e. atoms. electron, proton and neutron etc. The more scientist will be truthful with themselves the more they will realise that their is the Creator. And to Him belongs the Absolute truth rest all are just mere guesses...This atheistic Scientist are even confuse between genders (by the way there are only 2 ) let alone universe.....


ACoolKoala t1_jbbjw9v wrote

Actually coming from a singular point is different than coming from nothing. Sounds like you lack the understanding of how the big bang theory actually functions therefore I'll discard whatever insults you're hurling at people who believe it. I have to go to my job at the moment so don't have time to get into philosophical debates about religion but yeah, science is awesome and you should respect it instead of using illogical fallacies to try and pwn people who use it as the tool that it is. It's not a religion, its a way of thinking. That's also coming from someone who understands how religion works and grew up in a religious household. Learn to be skeptical of everything not just shit you don't believe. Be skeptical about your own beliefs because I am. I didn't say big bang was even guaranteed how the universe started. That's just where evidence leads us. Could change tomorrow and I'd be fine with that, that would just require overwhelming evidence to disprove. Beauty of science and critical thinking.

Humans may crave absolute certainty; they may aspire to it; they may pretend, as partisans of certain religions do, to have attained it. But the history of science—by far the most successful claim to knowledge accessible to humans—teaches that the most we can hope for is successive improvement of our understanding, learning from our mistakes, and a asymptotic approach to the Universe, but with the proviso that absolute certainty will always elude us. ~ Carl Sagan

The hard but just rule is that if the ideas don’t work, you must throw them away. Don’t waste neurons on what doesn’t work. Devote those neurons to new ideas that better explain the data~ Also Carl Sagan (Look him up and appreciate him, read a demon haunted world sometime)


Anotheraccount008 t1_jb8da6i wrote

Glad to see fans of The Expanse in here


GlandyThunderbundle t1_jb8k47e wrote

I bet they’ve been Holden onto those comments for a while, waiting for an opportunity to spring ‘em


kudichangedlives t1_jb8ai58 wrote

Also if they open a mirror system to grow food I would advise against becoming an on site botanist


ChickenChimneyChanga t1_jb8aygg wrote

Ganymede also has a thin oxygen atmosphere and is believed to have a saltwater ocean 200 km below the surface. This ocean would have more water than all of the water on Earth's surface.


Modern_rocko t1_jb92xq5 wrote

I thought oxygen was only present as a byproduct of organic materials ?


Cohibaluxe t1_jb9eanb wrote

Oxygen is the third most abundant material in the universe. It’s made at the end of the helium fusion process in massive stars, and our sun is 0.9% oxygen by mass.

There’s oxygen on Mars and Venus too, but in insufficient quantities to support the oxygen cycle. The fact that we have the oxygen cycle (part of that being photosynthesis) is why Earth has a much higher amount of oxygen, but it’s not the only source of it.


bearsnchairs t1_jba05j3 wrote

Molecular oxygen, O2 is seen as a marker for biological activity. Molecule oxygen is pretty reactive and over long time scales it will react with mostly anything and form oxides. If it builds up enough for you to detect it, there must be a source to counteract the sink.

Fun fact, oxygen is the most abundant element in earth’s crust.


jschild t1_jb9fsv3 wrote

Significant Oxygen only is, because oxygen is so reactive that it bonds with other elements pretty fast. Trace amounts are ok, but if you see a planet with 10-20% oxygen (and the atmosphere isn't super thin), it's almost certainly going to be life.


Modern_rocko t1_jb9g9zf wrote

That must have been where my mind was at - thanks for the clarification!


herbw t1_jbauynx wrote

Too damn cold for any but water ice. Liquid water unless proven to exist is not there.

Surface temp 90 to 160 K. 294 K is 70 Deg. F. So far below frozen water it's not even realistic to be liquid.


dusto65 t1_jbb8lwn wrote

I think the theory is that if you go deep enough, it gets warmer due to interior heating. Plus the added pressure that deep could help in melting the water. I think you may also not be considering that salty water changes phases differently than pure water


herbw t1_jbdohz1 wrote

There is NO empirical evidence existing or real that Ganymede has liquid water. Prove that it does, which cannot at this time. Empiricists consider the facts, and learn more. But we know suppositions compared to empirically tested and confirmed truths. Anything else is hardly en pointe to understanding events.


igby1 t1_jb8re6p wrote

Prove it


Budgiesaurus t1_jb91n2z wrote

How do you expect anyone to proof this when NASA and the like are still at the stage where they think it likely has more water than the earth's surface. There are strong indications for it, but a random redditor doesn't have a space telescope lying around to verify the Hubble's findings, do they?


JesseCuster40 t1_jb8hchu wrote

To Ganymede and Titan

Yes, sir, I've been around

But there ain't no place

In the whole of Space

Like that good ol' toddlin' town

Oh! Lunar City Seven


disneyvacafacts t1_jba6kps wrote

TIL our moon is the only moon named Moon.

That would be like if my daughter's name was daughter, but your daughter's name was Mona.


Jugales OP t1_jba9l32 wrote

Our solar system is named Solar System :)


SuperSimpleSam t1_jbajxme wrote

Because our sun is named Sol (or Helios).


disneyvacafacts t1_jbapowu wrote

Right, but our Sun is the only one. They are referred to as Stars in other Extrasolar Planetary Systems.


disneyvacafacts t1_jbap4yd wrote

Right, but our solar system is the only one. All other groups of planets revolving Suns are called Extrasolar Planetary Systems not Solar Systems.


herbw t1_jbau9mt wrote

Not so. Other stars can have their own solar systems. & the phrase can be more widely used than you imagine.


disneyvacafacts t1_jbb0ljb wrote

No, it's only used in scholarly papers to refer to our planet system.


dusto65 t1_jbb9h9x wrote

SOL-ar. We get the word solar from Sol. Using that logic, any other planetary system would be a star-ar system. Colloquially, sure, since we all get what you're saying, but to scientists, who love to "achtchually.." people, they need to be very technically correct


herbw t1_jbdobz4 wrote

Not really. You fail to see the bigger picture, Most All our knowledge is highly incomplete. We are not limited by too tight definitions and beliefs, either. Empirical, logical, practical, testing, checking always learning, growing, developing. That's what we do.


herbw t1_jbat7ch wrote

Luna more originally. Moon is English and was not here until very recently, Selene is the Greek name for the earth's sole moon, Luna is Latin, thus Lundi (Monday), Marti, Mercredi, Jeudi, Vendredi, Samedi, Dimanche.

Engish uses the Deutsch gods for days of week. Francais and Espagnol day names are very similar.

People need to get outside of their personal cultural mindsets now and then. The whole world and much larger Universe is NOT English. & surely not Americain,


dusto65 t1_jbb9nk0 wrote

The sole moon of one of Sol's moons?


herbw t1_jbdo4i1 wrote

Sol being our star has planets and those have moons. That's basic astronomy, which clearly most round here don't ken. By choice.


A40 t1_jb89ij1 wrote

It coulda been somebody! It coulda been a contender!


zephyy t1_jb8ikd1 wrote

So is Titan.


Dillinger0000 t1_jbbisxg wrote

Titan sobs in the corner....


AutismFlavored t1_jbc646n wrote

It’s ok Titan, you have an atmosphere and liquid hydrocarbon lakes. No one can take that from you


dogwoodcat t1_jbcqopy wrote

Don't underestimate us and our thurst for dino juice, now from outer space!


mythologue t1_jb91yel wrote

Kind of proud our largest moon is named for gay icon Ganymede!


herbw t1_jbas7qp wrote

Mercury is soid rock. the gases beingt blow away by strong solar wind and radiations.

If we get rid of the gases on ganymede, like a large furry dog which got it's hair clipped not much would be left.

Merc is rocky, Ganymede is gassy. There is no empirical, rational comparison. Mercury is WAY denser than Ganymede. Besides 'gany fooled around with Jove.


NYCRonnie74 t1_jbcc16o wrote

Aaaaand, 5 seconds later everyone goes back to liking ass photos on Instagram. Because that’s what today’s generation does to keep busy. We‘re devolving as species.


dave_hitz t1_jb8diu2 wrote

Don't let the astronomers know. They'll redefine it as a dwarf-moon planet or something.


fish4096 t1_jb99khb wrote

i'm pretty sure the orbit is going to clear boundary. but i know what you mean, i'm still salty about Pluto, too.


dave_hitz t1_jbbgxw2 wrote

I agree about the clearing. But they'll invent some new rule. "But it's smaller than a moon in the same solar system!"

I have a simpler rule. If it's big and round, it's a planet. Unless it's burning with the flames of a nuclear fire, in which case it's a star.

Some planets go around stars. Some planets go around other planets.

Let the planets proliferate.


fish4096 t1_jbdutkc wrote

gotta have clear definition of "big" then.

By diameter? Mass? Bigger then what?We could of course take Earth as ballpark and drive rules from there, but this wont get us far the more of universe we discover. There will be all kinds of odd objects that dont fit into our little bubble of categories.

The reason I'm upset about Pluto is because it's one of those "classic" discoveries, something that should be honored.


dave_hitz t1_jbfgcfu wrote

Big enough for gravity to squeeze it to round. Most asteroids are odd shaped rocks. They don't count. Get enough rocks to generate enough gravity to pull the rocks into a sphere, then you've got a planet.