Can Moons Have Moons?

[@n-steam]

The extension to this question is whether binary planets can exist, and whether they can share a moon, and whether binary moons can exist.. and could binary planets share a binary moon.. around binary stars.

[@xaphanofthenightfall1257]

i forget the names of the 2 moons, and even the planet they orbit. I belive its Saturn. But there IS two moons of it that share an orbit, almost. when the outer one catches the inner, they pull on each other. The outer one slows down while the inner speeds up. they swap possions and repeat this when the now outer moon catches the new inner again.

[@MustafaAlmosawi]

In principle, I think yes, as there there are multi-Star systems with binaries orbited by a binary pair that is orbited by another star all orbited by another. While no such multi-moon system has been found, it’s likely possible via analogy, though it’s not clear how stable these orbits will be in the long run.

[@damiensmith9240]

Yes, it would be a smaller version of the Alpha Centauri system, which is a binary star, with a 3rd, smaller star that orbits the binary.

[@charity9660]

The easy and fast answer is yes because space.

[@nocapoca5313]

Pluto and Charon

[@valerielhw]

Wouldn't it be interesting if there were an intelligent species living on a submoon somewhere in the vast cosmos. Imagine the mythology that could develop from looking into such a night sky.

[@marktaylor6553]

On Mars, one moon orbits faster than the planet rotates, the other slower, so even though they are going in the same direction, a planetside observer would see the two moons rising on opposite horizons and cross in the sky. Now THAT would make for some great mythology!

[@gebdemedici]

@@marktaylor6553 I had to take a moment to mentally figure out why this would happen, but that would be so incredibly cool to watch!

[@arminlutz8294]

@@gebdemedici Damn it took me a few seconds too long aswell to figure out why^^

[@marktaylor6553]

@@arminlutz8294 Don't feel bad guys, when I first read that many years ago, I had to sit for a minute and work it all out mentally too. Its been one of my favorite 'space trivia' facts ever since.

[@rojack79er]

@@marktaylor6553 well thanks now I have to go and work on my Martian Mythology for my book some more 🤣 cause that is a very fascinating detail that I've honestly never heard about until now.

[@BlazingSun39]

I vote for 'moonlet' as a substitute for submoon. It seems to fit quite well in my opinion.

[@Rishi123456789]

Subsatellite is the best term for what you call a 'moonlet', because Earth's satellite is already known as 'the Moon'.

[@DeveusBelkan]

I think it should follow that you would have a planet, a moon, a moonlet, and finally, a sub-moonlet. Submoon and moonlet would appear to most people to mean the same thing at first glance, whereas it is easy to understand that a sub-moonlet must obviously fall in line of a moonlet. It would reduce the ambiguity of the words. I don't think satellite is necessary a better term because if the argument is that ordinary people might be confused between a moon and the moon, they would equally be confused between a natural satellite and a manmade one. Satellite just has a more "professional" feel to it, but would fail to compound as a word, unless you have a satellite, a satellitetet, and a subsatellietet, which as a jumble of letters is a bit mind-boggling.

[@Rishi123456789]

@@DeveusBelkan Satellite is a better term than Moon. If normies can't tell the difference between natural satellites and artificial satellites, that's on them.

[@seriouslee4119]

Love it. And then I propose we call the moonlet's moon a "moonsicle". Like a popsicle, but for moons.

[@rebelgaming1.5.14]

​@@Rishi123456789 The term moon just rolls off the tongue better than satellite despite satellite being the scientific term. A moon ranking could work like this Supermoon Moon Submoon Moonlet Sub-Moonlet A ranking style using satellite would work like this Satellite Sub-sattelite

[@MrFreakRite]

If there's ever an Outer Wilds 2, they should definitely explore moons of moons. Maybe a planet with one moon that has one moon that has one moon. Or a planet with two moons that each have a moon.

[@lizardlegend42]

Or a moon that alternates between orbiting 2 planets 🤔

[@tbouchard2789]

In the future, we just call them moonlets.

[@antoniopetcu8688]

@@lizardlegend42 quantum moon all over again

[@tacofitness1876]

I really hope there's no OW2 tho

[@cabrinius7596]

@@tacofitness1876 maybe a different game by them

[@cjguy3510]

I’ve always had the question, could moons be gaseous? I know that the likelihood of something like happening is slim. I would assume that it would just be considered binary to another planet.

[@shrekeyes2410]

I dont think so, for something to be a moon you have to orbit a planet, and for that you must have lower mass than it and the planet cant have enough mass that it is a star. No idea

[@Fr333man]

@@shrekeyes2410 it will be based on electro magnetic fields, not mass, thunderbolts projects discuss that and much more in detail

[@shrekeyes2410]

@@Fr333man ohh ok

[@green5260]

@@shrekeyes2410 he seems like one of those "electric universe" guys

[@paulmahoney7619]

@@Fr333man why is it that we’ve been able to do so much in interplanetary exploration without accounting for electromagnetism ever in our trajectories?

[@nursemark447]

A moon's moon from this day forward shall be called a "kipping".

[@CoolWorldsLab]

Haha! I wouldn't inflict that upon anyone else!

[@ryanb9749]

Aye.

[@sarahbhingraj8035]

Agreed.

[@Outist]

Signed!

[@AkalonTheGrey]

How about an exomoon: 'kipping', and an exomoon's exomoon: 'kippen'?

[@nickhardy9651]

Since moon is derived from the word month, we could derive a name from the Latin word for week. Like Septimana or mana. So in short: planet, moon, mana

[@marcustrevor1883]

I like this one

[@onieyoh9478]

What do you call a moon moon moon.

[@nickhardy9651]

@@onieyoh9478 Maybe the Latin word for day - die Or maybe Pernox which means night. We could also cross that bridge when we get there. ;)

[@gives_bad_advice]

I'm in.

[@jaylewis9876]

Then latin for hour is the next logical step

[@ophiuchus203]

I'm a software dev, not an astronomer, so I'm not sure what specialties might benefit from a detailed hierarchy below "submoon", but from where I'm standing submoon seems just fine. Any further sub iterations of that relationship type seems like it could just be captured with the phrase "natural satellite"; natsats for short, as in, "Hey Jimmy, get me a natsat count of that submoon so I can calculate a landing approach."

[@michaelyoung7261]

Writers, I present to you your next HFY writing prompt.

[@ShyRaven2161]

Natsat is a good one

[@jtgd]

What if two planets have 1 moon, or one planet with two moons orbiting each other?

[@bunniiac]

@@jtgd i think the binary planets having 1 moon would just be called a moon, maybe a shared moon. and two moons orbiting each other could be just called binary moons :-)

[@patreekotime4578]

So when driving around on one would you use the natsat satnav?

[@kawaiipandax]

I think to denote a submoon, you should simple add an 'o' to the word "moon". So a moon orbiting another moon would be a mooon. You can repeat this pattern as many times as you like: a moon orbiting a submoon would be called a moooon. Naturally, this would classify planets as mons, and the stars they orbit as mns.

[@placeholder4029]

This is the best idea. Another idea: galaxies be called m-ons (negative o), and the galaxy groups they are in be called m-oons, and so on

[@Dondideeda]

And the correct way to pronounce it is to count a second for each o in the word.

[@chuxmix65]

Never would have guessed that I would find a new channel this evening. I was busy catching up on my subscribed channels this evening, saw the question and clicked expecting Simon Whistler (I wouldn't mind his take on this topic, mind you). I was so pleasantly surprised to find a scientist exploring a serious question in a fun and relatable way. Learned about the Hill sphere tonight. I may have heard of it before but with your explanation and the wonderful diagram at 3:31 it will now stick. That diagram shows the LaGrange points better than I've seen before. Subbed, bell clicked, and now I've got another back catalog to binge when I need one. Thank you!

[@audiburr2784]

I think the terms primary, secondary and tertiary would work when referring to levels instead of order. Planet > primary (moon) > secondary > (primary's moon) > tertiary (secondary's moon). Not sure I've illustrated the idea properly but hopefully well enough to be understandable. Great video.

[@SecularGeek]

I like the hierarchical nature of this solution, but I think we can make it even more generalized and extensible. First of all, we need a word that can be applied to any orbiting object, not just moons. Obviously, that word is "satellite". Next, we need a more extensible system for designating what level we are talking about in the hierarchy. Audi Burr's primary - secondary - tertiary system is excellent, and we can even extend it to "quaternary", but it breaks down somewhere after that. What would we call a satellite that is another five levels down the hierarchy? My suggestion is to use a number together with the word "order", as we do with derivatives. So, the Earth would be a first order satellite of the sun, our moon would be a second order satellite of the sun, a "sub-moon" would be a third order satellite, and if we got really crazy and wanted to talk about a moon of a sub-moon, that would be easy: it would just be a fourth order satellite. The sun, by convention, would be a zero order satellite. We can also extend the system outward, by specifying what the zero order satellite is. Thus, although the Earth is a first order satellite of the sun, we could also say that the Earth is a second order satellite of the galactic core - because the sun orbits the core.

[@anderssilfvergrip2099]

Eric Katz' suggestion with zero order, first order, second order satellite, etc, is reasonable and is what I was about to suggest too. But, I got stuck when it came to binary stars, or, even binary moons. Which is which in case they´re indistingishably equal? Equal can mean many things - in "size", mass, proximity to barycenter, diameter, level of "sphericalness", orbital shape, orbital "cleanliness", number of satellites, "size" of largest satellite, or, something else). Which parameter take precedence? Here one would need some well thought out ranking order of importance, perhaps like Pluto became a dwarf planet some years ago.

[@TheDrumstickEmpire]

@@anderssilfvergrip2099 perhaps order could imply a region? So, a new order every x distance from the body relative to the body’s side?

[@Blck0Knght]

I would fear that "primary" is already taken by the most massive star of a system, and "secondary" for the next most massive star in a binary (or n-ary) star system. While you could generalize the star naming system (so that planets of a primary star are secondary too, and their (regular moons are tertiary), you'd have the issue that the secondary star's satellites would all begin up one degree (planets tertiary, moons ???).

[@abloogywoogywoo]

When it comes to a system that has a world orbiting a Brown Dwarf, which orbits a main sequence star, do we refer to that celestial object as a planet or a moon of the dwarf?

[@hunterhalo2]

I really like these natural backdrops, adds something extra to already incredibly made videos.

[@archiox0628]

what amazes me more is how well cleaned up and mastered the audio is in post production, knowing this was recorded outside

[@CosmicCustodian]

@@archiox0628 he's likely to have chosen an area with minimal human noise pollution and has microphones set about around him to record the ambient sound which he can use to phase shift the vocal track to cut down on all the noise. He also likely has input gain up but using a noise gate with high threshold so it only records his voice when noise gate opens. I'll admit, even I was taken aback by the quality of his voice considering the background

[@Radnugget]

I kind of like the idea of calling them a Sublet (because they are renting space from another larger object that is also renting.)

[@unvergebeneid]

Ha, I was thinking moonlet actually

[@BI-11y_TheStormTrooper]

Honestly either are pretty good names.

[@bellebeacher6613]

Moonlet is cute🥰

[@DwightMoses]

@@unvergebeneid precisely!

[@marthanewsome6375]

I was thinking the same thing. Or moonlit meaning lit by the moon.

[@segsuc6399]

You deserve so much more subscribers. Your videos are so well produced and so extremely informative. Big up and keep going for one day soon I hope you reach a million and even 10.

[@johnterpack3940]

I clicked on this expecting quackery. Pleasantly surprised to find actual science. Somebody has already suggested the rather simple primary/secondary/tertiary designation for moons/submoons. That seems perfectly reasonable to me. I also like submoon. I very seriously doubt such a thing is stable enough to need additional levels. I would bet monumental amounts of someone else's money that we could search the entire galaxy and never find a moon around an earth around a neptune around a jupiter. That's just a razor's edge of a goldilocks scenario.

[@zebdawson3687]

You clicked on a Cool Worlds video from Professor Kipping and expected quackery? That’s pretty funny to hear! 😂

[@cornoc]

why did your mind jump to quackery

[@johnterpack3940]

@@cornoc Because there are a slew of channels putting out space-related nonsense. And "cool worlds" doesn't really sound serious to me.

[@thedoveston6781]

It's the best channel on KZbin

[@thedoveston6781]

@@johnterpack3940 I'd be interested to know your thoughts after a few more videos. I'm no astronomer/astrophysicist and the channel does a really good job of conveying new ideas to me

[@AlexAzureOtaku]

I am in no way connected to the fields of scientific research but these videos always fill me with wonder and hope enough to go the extra mile and learn about these subjects.

[@AlexKnauth]

In my own speculation among friends I've called them "meta-moons". I was imagining a hypothetical moon of Neptune (since that's the planet with the largest Hill sphere wrt the Sun) and a hypothetical meta-moon of that, and so on, but back when I was speculating on this I didn't even know that for prograde orbits it should be within half a hill radius.

[@Rishi123456789]

The name I've chosen for such objects is 'subsatellites'.

[@markg3025]

Professor Kipping truly a beautiful mind. Thank you Professor.

[@raideurng2508]

Considering the wild perturbations between small moons that go on in the Jovian and Saturnine systems, I think it's pretty safe to say such systems would be fleeting, perhaps even cyclic as highly elliptical orbits transition from orbiting the moon to orbiting the parent body. At the apogee of such orbits, the influence of other bodies could cause some wild stuff to occur, most of it being very brief.

[@ProtiumPower]

My mind is blown🤯 knowing why Iapetus has equatorial ridge and knowing that we have developed a good theory for it.

[@pcooper83]

The research I would like to see next on this subject would be about the probability of these things forming. Either from the original planet forming nebula or by capture. Also how a planet that used to have this arrangement that wasn't stable enough what the likely outcome was. E.g. if it is likely the submoon just becomes a parent planet's moon and if so what properties the orbit would likely have as a means to see if there is an indicator that a moon used to be a submoon of a particular other moon.

[@canaldohector]

in these situations I remember the "moons are planets" article With that in mind, I propose the following: 1st degree planet: planets that orbit stellar objects 2nd degree planet: standard moons 3rd degree planet: moonmoons and so on maybe we could call rogue planets 0th degree planets for fun's sake

[@N.I.R.A.T.I.A.S.]

I was not on board with this proposition until you mentioned zeroth degree planets, and that terminology sounds so cool to me that I am now 100% sold.

[@Essence1123]

Would our sun be a 0th degree planet? Would the blackhole at the center of the milky-way be a -1th degree planet? What defines a 'stellar object'? I propose all moon levels are based around Earth as a 1st degree planet. That makes Mars a 1st degree planet because we go down one degree to our sun (0) then back up one degree to Mars. Rogue planets outside our solar system not captured by a star would also be 0th degree because we go down two degrees (earth -> sun -> blackhole) then back up one degree to the rogue planet

[@TerraOmnia]

Are stars just big 0th degree planets? =D

[@canaldohector]

@@TerraOmnia I'd differentiate stars from planets by the presence of fusion in the core

[@Celestial_Reach]

Thank you for everything you do. This is something that has been absolutely amazing. I really hope you get to make the first confirmation. Your work is some of my favorite, qnd amazing, you inspire me to reach for my dreams. Thank you

[@UteChewb]

Thank you. As soon as I saw the title, I hoped you would talk about Hill Spheres. I wrote a novel where I had to work out the Hill sphere for a couple of bodies, though only planets. I was amazed at how much was uncertain in the calculation. Sounds like a ripe area for research for someone. Anyway, thank you, and subscribed. As for the name, I'd just stick with moon. My argument would be we could follow the example for 'island'. There are islands in lakes on islands. Still called an island. There might be a technical term, but considering the relative rarity, I don't think we need to fuss over it too much.

[@Zandonus]

This is really cool. I imagine with what I think i know about filters, great filters and biology in general that these submoons would be very unlikely candidates for life though? Short lifespan of the submoon in a relatively unstable orbit with a giant planet blocking most of sunlight, plenty of volcanic shenanigans to ruin your day etc..

[@geckorocketry]

In my opinion, I think calling a submoon, a submoon is perfectly fine because of the fact that dwarf planets are called dwarf planets. And a moon orbiting the submoon should probably be given a different name that does not include the name ‘moon’ in it

[@Bitchslapper316]

I'm sure in time dwarf planets will get their own name.

[@elmacho2789]

Submoon, micromoon, maybe something cool like quantumoon or nanomoon idk

[@matthieudirven6997]

Sub moonmoon

[@view1st]

@@elmacho2789 _Submoon_ sounds okay.

[@Mediocreinput]

Subway Moon

[@saladinbob]

A moon of a moon should be called Endymion who was one of Luna's consorts (the other being Jupiter but that's already taken). A moon of a moon of a moon would be a Menae, the collective name for Luna's offspring.

[@midaslucky4363]

I like this idea

[@caejones2792]

Me too. But isn't Menae plural? Would a single one be called a Mena?

[@staticgrass]

I think Manae as a collective term for moons of moons is a good one. Rather this than creating names for all of the daughter moons based on their position.

[@WitchMedusa]

I think sub-moon is the best but this is certainly my second favorite contender on the names.

[@ready1fire1aim1]

As Leibniz put it: “If an ontological theory implies the existence of two scenarios that are empirically indistinguishable in principle but ontologically distinct ... then the ontological theory should be rejected and replaced with one relative to which the two scenarios are ontologically identical.” In other words, if a theory describes two situations as being distinct, and yet also implies that there is no conceivable way, empirically, to tell them apart, then that theory contains some superfluous and arbitrary elements that ought to be removed. Leibniz’s prescription is, of course, widely accepted by most physicists today. The idea exerted a powerful influence over later thinkers, including Poincaré and Einstein, and helped lead to the theories of special and general relativity. And this idea, Spekkens suggests, may still hold further value for questions at the frontiers of today’s physics. Leibniz’s correspondent Clarke objected to his view, suggesting an exception. A man riding inside a boat, he argued, may not detect its motion, yet that motion is obviously real enough. Leibniz countered that such motion is real because it can be detected by someone, even if it isn’t actually detected in some particular case. “Motion does not indeed depend upon being observed,” he wrote, “but it does depend upon being possible to be observed ... when there is no change that can be observed, there is no change at all.” In this, Leibniz was arguing against prevailing ideas of the time, and against Newton, who conceived of space and time in absolute terms. “I have said more than once,” Leibniz wrote, “that I hold space to be something merely relative.” Einstein, of course, followed Leibniz’s principle when he noticed that the equations of electricity and magnetism make no reference to any absolute sense of motion, but only to relative motion. A conducting wire moving through the field of a magnet seems like a distinct situation from a magnet moving past a stationary wire. Yet the two situations are in fact empirically identical, and should, Einstein concluded, be considered as such. Demanding as much leads to the Lorentz transformation as the proper way to link descriptions in reference frames in relative motion. From this, one finds a host of highly counter-intuitive effects, including time dilation. Einstein again followed Leibniz on his way to general relativity. In this case, the indistinguishability of two distinct situations - a body at rest in the absence of a gravitational field, or in free fall within a field - implied the impossibility of referring to any concept of absolute acceleration. In a 1922 lecture, Einstein recalled the moment of his discovery: “The breakthrough came suddenly one day. I was sitting on a chair in my patent office in Bern. Suddenly the thought struck me: If a man falls freely, he would not feel his own weight. I was taken aback. This simple thought experiment made a deep impression on me. This led me to the theory of gravity.”

[@l1mbo69]

Cool but what does this have to do with anything here

[@AnimeHumanCoherence]

Your bot is broken.

[@brainblessed5814]

Day-night cycles on such submoons must be fun

[@JD3Gamer]

I think a good naming system for sub-moons might being an ordering system. What we call a moon would be a first order moon, a sub-moon would be a second order moon, a sub-sub-moon would be a third order moon, etc.

[@tbouchard2789]

In the future, we call them moonlets.

[@thiagopachecodearaujo4178]

Então nossa lua é um sub-planeta seguindo essa lógica ou um planeta de segunda ordem !

[@nedaheidari9260]

Hi! I am Neda Heidari, a PhD student at LAM, France. Thank you so much for sharing this video with us! Great job 👌 I am very interested in the moon detections!

[@ornessarhithfaeron3576]

What did you study?

[@nedaheidari9260]

@@ornessarhithfaeron3576 I work on detection and characterization of small planets, with two methods of radial velocity and photometry.

[@lj__ytrz]

@@nedaheidari9260 Intéressant, tu as fais quoi comme master pour arriver à ça ?

[@davidanderson_surrey_bc]

Curious that your username doesn't quite match your stated name.

[@nedaheidari9260]

@@lj__ytrz In master, I studied astronomy and in bachelor I studied physics.

[@ollywright]

I'm fond of 'moonmoon' and 'noom'. Very clear video! Looking at the new JWST deep field you realise somewhere in that image has to be a moonmoonmoon.

[@TheGarmisch]

Moon-moon. I'm calling it that until my death

[@henryd4331]

Now just imagine what eclipses may look like in these configurations ! And the math behind predicting them 🌕

[@myroslavnesysiuk730]

Day-night cycle in general would be interesting. It would depend on Jupiter's and Neptune's shadows in relation to Earth. Some pretty wild possible configurations are possible

[@GregArmWrestling]

4:59 "Sticking its moon out" that just sounds so weird 😂

[@17zie]

So happy to have found my favourite channel on KZbin!!

[@Outist]

This is truly unexpected, thank you for sharing amazing and inspiring information. I can only imagine your hardwork and great efforts for the community. Thank you again sir. 💖

[@Nefville]

We're still too hung up on our own solar system. We think every 'hot Jupiter' MUST have formed in the outer solar system of whatever star and then move in over time. What if it formed _before_ the star started fusing hydrogen? It would be colder maybe even fairly close to the proto-star. I'm sure I'm likely wrong but it bugs me how much we favor our own planet and solar system even after finding that *we* are the anomaly.

[@marcpeterson1092]

I think we currently assume that planetary systems all form at the same time. If a planet forms first, that idea would certainly be upended. I think I would want a mechanism for a planet to form first. It would have to be independent of the star.

[@worldcomicsreview354]

Most star systems are binary, the hot jupiters are likely failed companions. Also current exoplanet detecting technology favours both massive planets, and ones close to their stars. Maybe one day hot jupiters will be rare.

[@jasonreed7522]

The solar system we live in is simply way easier to get good data on, everything that is far away suffers from sample bias and generally poor data. But we do have the laws of physics as we know them and conputers, so we can run simulations/calculations to see what is possible or not. (Possibly does bot mean findable or exists, although in the infinite universe possible = inevitable)

[@marcpeterson1092]

@@worldcomicsreview354 The part about failed binaries is reasonable. But the comment about bias toward hot Jupiters is out of date. Technology has improved to the point where we can see a lot more Earth-like planets. Trappist 1 being a good example.

[@z5197]

We also attribute properties to all these other bodies in Sol, Terran, Jovian, etc. terms. You said it yourself: a "hot Jupiter" (unless you're referring to that sexy little gaseous thing we recently found with TESS? TOI-2180 b? Because while she IS bangin', by all reports that's one icy-cold, frigid planet. Supposed 3x Jupiters mass too, but for gods sake DON'T let _her_ hear you say that!).

[@timothyherzog9961]

I told my wife about this, and she insisted that the naming should be romantic, and mentioned that (in English) there are two letters in between the first letters of Sun, Planet and Moon. Hence, her proposed convention is: Sun, Planet, Moon, Jewel, Gem, and anything after that would be Dust (or at least names beginning with 'J', 'G' and 'D'). Well, she's an engineer, not an astrophysisist! 😂

[@Great_Olaf5]

Honestly there are worse ideas. She's got my vote.

[@timothyherzog9961]

@@Great_Olaf5 Hahaha! Cheers! Given that Astrophysics is filled with interesting names and terminology like spaghettification and nuclear pasta, I figured it was worth putting this out there 😛

[@appye7994]

Hmmm. Joon, Glanet, Dun ... Bun? Whoops. It'd have to start with an A, so ... Let's call it the Ass. Science!

[@kyanos-asteras]

Now, another relevant question: Can a moon be tidally locked around its star, rather its planet?

[@arminlutz8294]

Im certainly no expert but i dont think so. Tidal locking occurs by the gravitational interaction between both bodies slowing down the rotation until it matches the time for a complete orbit. Since the moon has to be in the hill sphere of the planet the gravitational effect of the star is certainly less than the effect of the planet so why should the moon interact with the weaker candidate if at all? Maybe there are some crazy dynamical interactions that i just dont have a clue about but otherwise it sounds very unlikely.

[@seangreen4896]

The Earth's moon is tidally locked that's why we always see the same side

[@kindlin]

No, the fact it's a moon means the planet it orbits has more influence over it than the star in the system, so there is no way the star can dominate the moon and cause some kind of resonance without disrupting the orbit entirely.

[@jeremychicken3339]

Yes, just look at our moon.

[@kindlin]

@@jeremychicken3339 The moon is tidally locked to _the earth,_ the moon's planet, not the sun.

[@kavyulgupta8712]

I'm really into astronomy and this concept really gave me food for thought. Please keep bringing up topics like these. It forces the mind to think out of the box creatively......😊😊 And for the 'submoon', I would've really called it :-- VENUSA(S)...... I don't know, it came to my mind randomly, just out of the blue and I really liked it...😂😂

[@joz6683]

Great video as always. I remember reading that our moon could not hold a moon of it's own due to the luna mascon that lay under the surface. I remember reading this as the reasons that satellites placed in luna orbit by the Apollo Program failed quickly. However I think that a submoon is a great idea but think it would be something that would exist in young systems.

[@SpaceAngelMewtwo]

So, as an Elder Scrolls fan, I simply have to put forward the idea that a submoon should be called a Secunda, and its parent moon be called a Masser after the moons Masser and Secunda from The Elder Scrolls. It is the first example I can think of when it comes to a fictional case of a moon having a submoon. In this case, Secunda is a submoon of Masser, which is a moon of the planet Nirn. It's not an entirely accurate depiction of a submoon because Nirn is presumably an Earth-sized object, Masser is presumably a Mars-sized object, and Secunda is presumably a Moon-sized object, but The Elder Scrolls is a high-magic medieval fantasy series and not science fiction, and it still makes for a pretty cool night sky in the game.

[@Angel_Kittichik]

I second this! (I've only played ESO though, so I didn't know the moons had names other than Jone and Jode. 😆)

[@jeffbenton6183]

Secunda is Latin for "Second". Perhaps this is a reference to the old practice of calling moons "secondary planets" - hence, Secunda is a secondary moon (just as a secondary planet is a planet that orbits another larger planet, so a secondary moon is a moon that orbits another larger moon)

[@revenevan11]

My guess, being only 2.5min in to this vid, is that whether a sub-moon is possible depends on the eccentricity and distance of the main moon's orbit around the planet, as well as how massive each of them are. I'd guess that tidal forces and just the chaotic nature of a 3-body system would be the main obstacles to stability, but I switched my major away from physics so 🤷‍♂️ (I still obviously love it, though! 😁)

[@unvergebeneid]

A star-planet-moon system is already a 3-body system. So with a submoon you get four bodies.

[@physicslover4951]

@@unvergebeneid Star is also orbiting around the galactic center... so five?

[@ShinyRayquazza]

@@physicslover4951 Stars do not “orbit” their galactic centers in the same sense that planets orbit stars… so no.

[@physicslover4951]

@@ShinyRayquazza ...what's the difference? (I am genuinely curious)

[@ShinyRayquazza]

@@physicslover4951 there is no central object or point in a galaxy to which a star is gravitationally bound. Every star in the galaxy is influenced by every other star, not to mention all the other stuff (including dark matter). A particular star’s motion is predominantly influenced by the mass inward of its location, of course, but you cannot cleanly approximate this as a point source like you can for a planet’s star. And the effect of interactions between nearby stars in a galaxy can be significant - you certainly don’t get nice elliptical orbits. Looking at what you _do_ get involves the study of collisionless dynamics, if you want to dig deeper.

[@lossless4129]

Dude, I can’t get enough of your channel!

[@Noctua07]

Your final thoughts are always so inspiring and almost always put into words what I feel myself.

[@velnz5475]

Suggested Vocab for such objects: Moons: Natsats: Natural satellites Snatsats: Sub natural satellites Plasats: Planet sized natural satellites Astsats: Asteroid sized natural satellites Quasets: Temporary natural satellites Aethsats: Natural satellites with atmosphere (named after Aether) Hephasats: Natural satellite with volcanic activity (named after Hephaestus) Ringsats: Natural satellites contributing to some contribution to a ring system Asteroids: Zweistroids (or Bistroids): Binary asteroid systems Planets: Zweinets (or Binets): Binary planetary system Dreinets (or Trinets): Trinary planetary system Minets: Minor planets Vulnets: Mercury like small terrestrial close orbit planets (named after Vulcan) Ginets: Major gas giants Brownets: Brown dwarf planets Hadenets: Hot jupiters (named after Hades) Snepnets: Sub neptunes Posnets: Minor gas gaints (named after Poseidon) Promnets: Super earths (named after Prometheus) Aquainets: Earth clones (named after Aquaites) Odd astronomical planets: (suffix O.A meaning Odd Analog) Clocoas: Chlorine planets (named after Cloacina) Rogueoa: Rogue planets Orcusoa: Long orbital period planets (named after Orcus) Liberoa: Planet not on a stellar plane orbit (named after Liber) Minervoa: Phosphorus planet (named after Minerva) Lavernoa: Tidally locked planet (named after Leverna) Pomanoa: Coreless planets (named after Pomona) Kavehoa: Iron planet (named after Kaveh, an ancient Iranian blacksmith) Zaroa: Lava planet (named after Zoroaster, ancient Iranian founder) Hycanoa: Hycean planet Deavoa: Dessert planet (named after Deava) Pulsoa: Pulsar planet Toroidoa: Toroidal planet (donut planet) Eishoa: Ultra cool dwarf star planets (named after Eisheth, a demon in Hebrew mythology) Zizoa: Disrupted planets (named after Ziz, a Hebrew griffon) Illuyoa: Ocean planets (named after Illuyanka, a Hittite serpentine entity) Rocoa: Ultra short period planets (named after Roc, a Arabian legendary bird of prey)

[@GalenMatson]

Nice work! I'm definitely on board with the planetary names.

[@michaelfoye1135]

Excellent suggestions. I hope you will be pleased if they turn up in fiction or ttrpg literature.

[@Xeno_Bardock]

A moon with its own magnetic field is more likely to have submoons orbiting it or capture one into stable orbit. Ganymede is more likely to capture a submoon into its orbit someday. Magnetic field is also the likely reason why planets and moons orbit in the same plane.

[@rubaemaster7036]

Honestly, it makes sense the answer is yes since the moon orbits us, we orbit the sun, and the sun orbits a black hole at the center of our galaxy. To me that makes it feel like the only limit, other than those gravity areas you mentioned, is the amount of mass getting smaller. I think I would think, getting bigger, the black hole at the center of our galaxy might be able to orbit something unknown with a greater gravity and such an idea with continue indefinitely. Hence, we should be focusing bigger, not smaller in my opinion.

[@Zakon213]

Ever since I was introduced to this idea in the game Starbound, it just made sense for a planet with its moons to orbit around a huge gas giant. Makes for cool skyscapes as well

[@dudethebagman]

Maybe we can refer to moons of moons as grandmoons, and to their moons as great-grandmoons, etc. Alternately, we could refer to moons as grandplanets of a star, and moons of moons could be called great-grandplanets of the star, etc.

[@RedBlaze45]

I've got a suggestion for the sub-moons. Planets of third orbit order. This would turn moons into planets of second orbit order and planets into planets of first orbit order. What do you think?

[@marcustrevor1883]

Sensible but boring XD

[@RedBlaze45]

@@marcustrevor1883 to be fair, it would make the Solar System far more interesting. We'd group the major moons of the planets and dwarf planets in the same category as the other eight planets while still keeping a distinction. Heck, many moons of Jupiter are bigger than Mercury and we considered them like less important! That would make the number of planets in the Solar System from 8 to about 40, how cool is that?

[@brianarbenz1329]

PTOs? The Parent-Teacher Organization might consider that a trade mark infringement.

[@princeoftonga]

How about Second Order Moons as a designation? On earth you have enclaves of countries, a second order enclave is when you have an enclave within an enclave! This designation also has the advantage of being adaptable, if anyone finds a satellite orbiting a second order moon then that object becomes a third order moon and so on.

[@RedBlaze45]

@@brianarbenz1329 what do you mean?

[@bwhog]

When you got to Iapetus it raised one additional question in my mind. The analysis seemed to assume a submoon around a plant with only one moon (like Earth.) But what happens if that is not the case? What happens to that submoon when you consider the gravitational effects of multiple satellites orbiting the same planet, ala Jupiter or Saturn? Also, there's one other situation where it seems reasonable that a submoon ought to be able to exist around a moon that is closer to a planet and that would be a submoon in polar orbit aligned with the direction of the moon's orbit about its plant. (So the moon and submoon are effectively at the same distance from the planet.) In a sense, in that configuration you might consider both to be moons of the planet and not a hierarchical arrangement. I don't know that anything such as that can exist but it presents an interesting picture.

[@JosephRussellStapleton]

Interesting idea.

[@JavSusLar]

Some days ago a question came to my mind, and I think you can answer it: let's imagine our solar system hadn't had any ringed planet like Saturn. When would humanity have envisaged such objects?

[@desan476]

i was thinking about this when i was looking at Saturn with my telescope... i think that our (scientists not me) understanding of orbital gravity is sufficient enough to suggest this idea. just when you think about debris from crashes in space and thinking about "where would they go" is enough to get some idea about rings. but it would surely be "WOW" moment expecting this phenomenon and then seeing it for the first time... i remember the feeling seeing Saturn for the first time on my own eyes.. and i even knew it has rings.. its beautiful

[@versaviabrutaru9872]

You make everything seem so easy, the explanations are fantastic! Thank you!

[@eyeofthepyramid2596]

Wait furries exust in real life 😳

[@PowerScissor]

I felt like the Moon was 20cm closer 5 years ago....thanks for confirming!

[@jamesknapp64]

Sub-moon seems like a fine term. My gut tells me that sub-moons are "fairly" rare, requires something like one in every million or so systems have sub-moons.

[@Carewolf]

If they are sufficiently rare I would rather keep the generic term "satellite".

[@johndunphy7835]

I loved this. Especially your closing statement. Although i do love living in our age of discovery, sometimes I try and imagine what it must have been like for starseekers before voyager and mariner took to the skies and proved we were alone in our solar system. To look up at mars and beyond and believe that maybe someone was looking back must have been an amazing feeling.

[@calebgriffin4214]

First of all, for this question I always imagined it would be most viable in a system with a superjupiter planet and a brown dwarf behaving similarly to a binary system. Then, what would normally be a planet in that system would become and moon, and what would be a moon becomes a natural lunar satellite. Second, would it be possible to effectively negate the effects of tidal acceleration by having a moon with a orbit equal to the rotation of it’s planet?

[@lerkzor]

Thank you for the explanation. I have always been confused about the mechanism of lunar migration, and your phrasing has enlightened me somewhat.

[@WitchMedusa]

When this video first started I thought "moonmoon" independently cause it sounded silly & I liked saying it. But I think sub-moon sounds much better & more professional. As if to imply planets & their orbital satellites can be organized into a hierarchical structure such as a file system for a database. Galaxy > planet > moon > sub-moon, idk if this is how it would be organized, but as someone who is very particular about keeping things neatly organized I quite like the name sub-moon & believe your choice is spot on.

[@hydrolito]

Universe > galaxies > galaxy > solar system > sun > planet > moon > submoon

[@RobynASDxxx]

I call. them Moons, Mooons and Moooons lol

[@jssomewhere6740]

M-MOONS, or smoons, gotta go for something not clinical remember y'all are Cool Worlds. So give them a very Cool Worlds name. Being the best gives a lot of latitude, and you have earned extra. Love hearing more and more referencing you and your team. Should give you a lot of pride.

[@CoolWorldsLab]

M-m-moons.... haha I like it! Thanks Js!

[@ChemEDan]

@@CoolWorldsLab "Moon" with a cow accent 🐄

[@RobertWF42]

There's a theory that Venus once had a moon that spiraled in over several billion years (due to Venus's slow rotational period) and collided. This would explain Venus's surface appearing to be no older than several hundred million years.

[@Tjalve70]

I would disagree with that. I would say the reason why Venus' surface is so young, is because it DOESN*T have a moon. Whereas Earth has plate tectonics because we DO have a moon. Just my opinion. Not fact.

[@icaruswindrune7116]

@@Tjalve70 That doesn't necessarily mean anything though. Plate tectonics would make it so that the surface of a planet would be relatively young - thus not having it would possibly make the surface ancient (like that of Mercury, where the oldest portions of its surface is nearly as old as the solar system itself). With that said, volcanism also can keep a surface relatively young, Io is an example of this - as is Mercury (some of its surface is as young as 500 million years old due to volcanic activity). Venus also shows evidence of such, yet it also shows a pseudo-plate-tectonics due to its mantle plumes acting like subduction and diverging zones.

[@Tjalve70]

@@icaruswindrune7116 Yes, you're right. I didn't say that it was a given that our moon has made that difference. But I BELIEVE that our moon has made that difference.

[@bit-tuber8126]

Something I've wondered about for some time. For history I like "moon" and "submoon" for simplicity. As a computer programmers I'm wondering about sub2moon, sub3moon for the extras. There would likely not be that many of them and not having a punctuation mark (including superscripts, subscripts, etc) would make web searches more practical. Web searches should always be considered in naming new things.

[@gamersworld1296]

why even moon let's make it sub planet

[@holgerz1241]

I suggest the word glant for a submoon. Thanks a lot for that informative video. I love the idea of a civilization living on a glant (or kipping or mana) and watching their moon and their planet and their sun rise. I hope to see the movie soon.

[@silenttoxic707]

This dude is so ripped and badass looking. He's probably drowning in ... yeah lmao

[@N0Xa880iUL]

No, because then it becomes a three body problem and is chaotic and unstable. Sooner or later the smallest object collides with either of the bigger ones and is assimilated.

[@KentheDeer]

Cool video; an interesting conundrum to ponder. I’m certain the universe has many secrets to reveal to us still. We just have to keep looking!

[@Fyrwulf]

Hey David, I just want you to know that I found a submoon in Elite: Dangerous. Considering this game predicted the Trappist-1 system down to the position, star class and mass, plus the number and configuration of planets, I think it's safe to say that the math checks out.

[@myfreinds764]

I was thinking of this, Thanks for making this video

[@Vistico93]

I noticed a version of that tidal migration you mentioned when trying to create an Earth-like planet with two moons in a gravity simulator. I started with ones that were large (like 25% Earth gravity and 10% Earth gravity respectively) and it quickly destabilized with the outer one becoming a planet in its own right (experimenting with different orbital distances didn't help - like one moon would crash into the other or the planet itself!) but they seemed stabler when I made them much less massive (or if I put the larger moon on the outside - it seemed to shepherd the smaller inner one) but I don't know if they could last billions of years

[@KateAustinTx]

Pertaining to the rotations of the moon, The "early years" of earth rotation was about 6 hours and the moon was a lot closer and look a lot bigger to earth. The weather and tides must have been massive.

[@1zsn303]

12:07 Second order submoon

[@Postntalkmemes]

This was immensely enjoyable, we need more.

[@Octobris]

The fact I thought of "submoons" in the beginning and you actually used that word later in the video, wow :D

[@mysryuza]

That’s a good question. Seeing how there’s TON-618 and Tres-2B, at this point almost anything could be possible

[@SubwayStation]

i was waiting for a video to discuss this

[@jar4900]

if Iapetus did in fact have a sub moon but later lost it, it might possibly still be within Jupiter's orbit, the best candidates for what might of been Iapetus's sub moon could be what we consider a small moon of Jupiter, especially one that is close to Iapetus

[@vaskauzunova5997]

I had a primary school math teacher who used to say that the more we know, the more we become aware of what we don't know. (He illustrated it by drawing 2 circles, the inside of which is what we know. The bigger they become, the larger their parameters are and the more of the unknown they "touch".) So I'd argue that we could never live in a time when everything has been discovered. And even if we could, what a boring existance would that be.

[@Jason-cf1xn]

Great video. One thing I've always wondered is why we haven't named our moon yet.

[@allwaizeright9705]

Yes - any object with mass can have another satellite. I remember reading in my TIME/LIFE - The Universe book - one astronomer once said the PLUTO couldn't have a moon. The more we discover about the Universe - the more we are amazed at what is out there...

[@jasmijnwellner6226]

I immediately want to put numbers on things like this, based on how deeply the orbit nests. A star would then be a 0-Orbit, a planet is a 1-Orbit, a regular moon a 2-Orbit, a submoon would be a 3-Orbit, and so on.

[@nickgraham6720]

Very good video, thank you :)

[@chr13]

7:11 What does the symbol next to Sean Raymond's name mean? He doesn't seem to be dead.

[@TheRantyRider]

Some time ago as part of a universtiy course I was asked how we would number moons of exoplanets, the latin numerals seemed the most obvious as it wasn't part of the [star name] - letter system, I'm glad to see it was taken up ;-) As for sub sub moons, perhaps the musical system should be used, after semi quaver you don't get semi-semi-quaver and then semi-semi-semi-quaver, it goes something like demi- and hemi-.

[@Jasmixd]

I'd say the easiest would be to use a simple numerical naming system. A normal moon would be a 1st-degree moon, a moon of a moon a 2nd-degree moon and so on. That would also make planetes technically 0th-degree moons, which I find nifty. We could also find a new term/just use the word "planet" and consider moons the 2nd-degree planets. Maybe use "satellite" and consider stars to be our baseline? As in, stars are 0th-degree satellites orbiting the center of the galaxy, planets are 1st-degree, moons are 2nd-degree etc. but then a whole galaxy could be called a -1st degree satellite if it orbits something (I have no idea how galaxies move in relation to each other, so apologies of that doesn't make sense). I think adopting a simple system along the lines of what I described would be best.

[@Knightly_Artworks]

"I heard you like moons, so I gave your moon a moon and some other moons a moon with moons"

[@IONATVS]

While I think other solutions are better, the way I have most commonly seen to construct terms where you’d naturally want to apply the same prefix multiple times is to find 3 or 4 prefixes with the same literal meaning and alternate them. So using the equivalents of “sub-“ (which is from Latin) from Germanic roots you get “under-“ and from Greek roots “hypo-,“ so putting them together you could get “undersubmoon” for a moon of a moon of a moon, “hypo-undersubmoon” for moon of a moon of a moon of a moon, “subhypo-undersubmoon” for moon^5, etc. While for most non-joke purposes I’ve only seen this method of construction used to the second level (undersubcommander, super-hyper-awesome, etc) the traditional names of small musical notes follow this pattern as well, with an eighth note being a “quaver,” a 16th a “semiquaver,” a 32nd being a “demisemiquaver,” a 64th note a “hemidemisemiquaver,” a 128th a “semihemidemisemiquaver,” (literally a half-half-half-half-quaver) and such ad infinitum

[@lightincircle5982]

I always searched for this.but no reponse until you did this!,thank you!

[@divergentdemigod1272]

Hey, could you do a video on rogue planets? Like is it possible a rogue planet could under perfect conditions support life or be terraformed?

[@akash7437]

My first thought the instant that I looked at the thumbnail for this I thought "wait, why have I never thought of that before?"

[@fuffoon]

If the data is true, then possibly the moon's moon has a moon too.

[@richardmercer2337]

"On the Moon's moon's moon, it's always June, the only month of the year!" A little musical ditty from many years ago -- no further info remembered.

[@prototropo]

I'd wondered about this since I was a kid! I assumed, given the utter absence of any mention of "sub-moons," that some limit of comparative scale or orbital hierarchies was the obstructor--such that only two relationships were supportable: the sun/planet and planet/moon. Beyond that the necessary difference between the biggest and smallest of a three-body system disallowed a jump up or down in added orbits. But a ten-year-old no doubt missed a number of papers dismissing my juvenalia mira. Had I imagined Dr. Kipping's videos falling to Earth, I would have just waited for his answer.

[@scottsaldivar8599]

We’ll call it a “Tsuki” Japanese for moon 月

[@ricardoalbuquerque7665]

When I was in high school my textbooks often referred moons to be "secondary planets", so I suggest that a moon orbiting another moon to be called a "tertiary planet".

[@Solid.Worlds]

sub-satalite would be a good name for a submoon

[@PObermanns]

I have played with simple orbital programs, but I never imagined such complexity. Good thing that I switched my major to engineering.

[@ihaveapsr7]

ok, technically planets are moons of stars and then a moon of a planet is a moon of a moon, so suns are counted as moons due to them orbiting black holes (rouge stars not included) so they are a moon of a moon of a moon. BUT we can talk about binary star systems with a star orbiting the other and in that case, a moon of that planet is the moon of a moon of a moon of a moon, very confusing but if we have a mega Jupiter size planet and a Neptunian size planet with a small planet orbiting that then we have a moon of a moon of a moon of a moon of a moon. But hey, that's just a theory A SPACE THEORY

[@Kaibear]

Now, as JWST is in place... Is there any further data on exo moons or even the chance for you to observe your previous candidates?