Gas Giant Moon Systems and Habitable Moons

More moons! Gas giant moonbuilding featuring shepherd moons, major moons, captured asteroids and, of course, habitable moons!
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► Planets : goo.gl/KWhpYd
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► Languages : goo.gl/KUng4y
► Seasons: goo.gl/ekyzh5
► Moons: goo.gl/swLfbo
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ARTIFEXIAN ON THE INTERWEB:
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USEFUL EQUATIONS FROM THIS VIDEO AND THE LAST:
► Density: (% x p) + (% x p) ... etc
► Mass: R^3 * p
► Surface Gravity: M / R^2
► Hill Sphere: a * (m / M)^(1/3) x 235
► Roche Limit: 2.44 * R * (pp / ps)^(1/3)
► Orbital Period: 0.0588 * (R^3 / (M+m))^(1/3)
► Ellipsoid Mass: p(4/3)πabc
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FOOTNOTES:
► 00:33 : The upper limit is the generic roche limit and the inner limit is based on the average inner limit of the ring systems in the solar system. In "If Earth had Rings" I suggested that the inner limit of a ring system will coincide with the upper limit of the Earth's atmosphere, because we don't care about the habitability of the gas giant itself we can play fast and loose with this inner limits. There is data to suggest that Saturn's rings (however tenuously) extend down to it's "surface".
► 02:32 : First order mean motion resonances are the most stable, i.e., 9:8, 12:11 etc
► 03:16 This relationship holds for the solar system but it's not known if it will apply to exo-gas giants.
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CREDITS:
Music:
"Unwritten Return" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0
creativecommons.org/licenses/b...
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Thank you all so much for watching…Edgar out!

[@gingermcgingin1733]

A cultures mythological response to a horseshoe orbit would be interesting. "Elder Xyani, what's with that big thing that appeared the in sky? Is it going to hit us?!" "Fear not, little one; it is but the braggart god Wiweü'næ, who is jealous of Giæo & so always challenges her every year, but always runs in fear before they fight."

[@goofyahhgamer4827]

that's actually a pretty cool analogy for two moons; nice work

[@leviathan3702]

@@goofyahhgamer4827 my planet's name is alreadyi it's a gas giant size of Saturn it's small but dancer it's a bluish color it has a moon has oceans continents and Life the Moon is smaller than Earth less denser it has ocean seas made of saltwater the gas giant is not visible in the sky it's atmosphere is made of methane and Ethan and oxygen it offers the gas giant of a distance of two lunar distance it has no intelligence species but still life the Moon's name is oka it's actually the smallest of the gas giant the largest mood of the gas giant is not named and it's the signs of Mars

[@froogletanimations1086]

Sounds Irish or Greek

[@smartart6841]

Ok thats good byt a kid wont call him ELDER xyani. Instead, xyani

[@gingermcgingin1733]

@@smartart6841 you do realise that this hypothetical alien culture is completely different from your own, right?

[@798Muchoman]

The gas giant does not need to be within the habitable zone to host a habitable moon. Europa is hot enough to be habitable and maintain liquid water because of its resonances with Jupiter and the other Jovian moons. Specifically, because of the extreme tidal forces those resonances cause. It could be possible to have a moon be so warm by this kind of heating that it has an Earth-like climate. These moons also do not need a magnetic field themselves; that of the gas giant is more than enough to extend out and protect them.

[@test_johndoge]

John Maguire well it aint habitable on the surface

[@trappist-1e]

test_johndoge still habitable under the surface

[@test_johndoge]

Lemob i know but the way they implied it seemed like they meant on surface

[@trappist-1e]

test_johndoge ah ok

[@castlebravo2023]

I could imagine life evolving on an ocean floor and over the course of time adapts to utterly inhospitable terrestrial conditions.

[@geoffreybrunell5592]

You had me at "James Cameron's Pocahontas".

[@Artifexian]

It's true though

[@Zarsla]

Me too.

[@christiandinkel8481]

he had me at "one radii" ;-)

[@joanduthie1689]

This gave me a hearty chuckle. 😄

[@emmanueltidor1996]

Oh

[@yaumelepire6310]

Reality: "This look a bit... errr... hum... improbable..." Me: "Shut up!!!"

[@macaroon_nuggets8008]

Good thing the universe is infinite. So no matter how improbable it is, if it has even the slightest chance of existing/happening it will happen somewhere at some point

[@blastyfs2]

@@macaroon_nuggets8008 There is far too little data to claim infinity, it is a much greater chance that the universe is finite. There is a great deal of data to suggest that the universe is expanding, if it is expanding then it has a border and is not infinite. We can only know what we observe and there is just so much that we do not know, all we know is what we can see outward from within our solar system so far.

[@animationspace8550]

@@blastyfs2 *shhhhhhh* , you are ruining it!

[@firstnamelastname7227]

blastyfs2 even if it’s not infinite it’s several million times bigger than the amount of ways quantum particles can be arranged, so anything that can happen, will happen. Edit: it would actually probably be replicated several times due to the sheer amount of space in space

[@realmless4193]

Humans: "This looks a bit... errr... hum... improbable..." Reality: "Shut up!!!" Is far more common

[@mven]

Wouldn't capturing an unusually massive satellite tend to wreck the nice ring system you constructed?

[@hamstsorkxxor]

Or create it by smashing something.

[@Artifexian]

Both. It could wreck the rings or it could cause further collisions and create new rings.

[@papisuckmypoosay69]

that's another problem, the giant satellite would mess up the orbits of other satellites, either throwing them out of the system or causing them to spiral in towards the gas giant, or best case scenario their orbital eccentricites increase/decrease

[@YYHoe]

Look at Neptune. His moons were affected by the capture of Triton, especially the outer moons like Halimede, Nereid and Sao. The former inner moons were broken apart and reformed as six of the seven inner moons. Hippocamp was formed when it was knocked off Proteus. Neptune may have gotten his rings due to this too.

[@pufthemajicdragon]

@@papisuckmypoosay69 If you're going with the capture method, most of the natural satellites of a gas giant migrating inward would get lost during the migration. This is due to interactions with intervening protoplanets, changes in tidal forces from the increasing proximity of the sun upsetting previously stable orbits, and just the amount of time such a migration would take. A quick web search found a fun Harvard study on the subject from 2001. The loss of moons is one reason mentioned in this video why Artifexian chose the captured moon scenario for the focus of the video.

[@kevintylerbobbitt7926]

OMG They should make a move about 2 habitable moons with horseshoe orbits and one get techlogically advanced before the other!!!

[@jdlenl]

and the space-age planet visits the bronze-age planet and is like "whaaaat"

[@faquytjub4371]

You mean a movie, right? I can totally see this as a Star Trek episode!

[@ganaraminukshuk0]

Just imagine how each civilisation would portray the other, as in, how the less advanced civ would see a world that would always pop into existence and recede into nothing; could that civ see that as their future (or demise) literally popping in and out of their existence?

[@davidk1308]

I can write a book from the technological civilizations standpoint, and switch between the 2 after they land on the other moon :)

[@davidk1308]

***** Yep, see a new thread in the lounge :)

[@bg1052]

"could this happen in real life? Eh... probably not" 4 years later "News: according to NASA we've found two Earth-like moons on a horse shoe orbit"

[@gingermcgingin1733]

When you have a sample size as big as the universe, 'probably not' means 'most definitely'

[@extratropicalcyclone8567]

@@gingermcgingin1733 but considering that the universe is much bigger than Russia the closest of such moons could be as far away as 1000 light years or maybe such an earth like horseshoe moon may not even exist in our galaxy

[@ortherner]

2 years away

[@bg1052]

@@extratropicalcyclone8567 Much bigger than Russia? That's a weird way of putting it.

[@tatianatub]

@@gingermcgingin1733 the odds are astronomical

[@KlaxontheImpailr]

The horseshoe orbit thing blows my mind!

[@Crick1952]

Mine too. Truth really is stranger than fiction.

[@Artifexian]

Science always better than magic.

[@bemk]

+Artifexian Earth actually has a horseshoe orbit with an asteroid, going by the name of Cruithne. You should look it up. Also, you sound Irish, so here's a question from a Dutchman learning Irish. An bhfuil aon Gaeilge agat? If so, you're going to be able to pronounce the name of Earth's pseudomoon perfectly :)

[@NikodAnimations]

​@@bemk It is not a horseshoe orbit. It is just a normal elliptical orbit with a semimajor axis of 1 AU.

[@OctorokSushi]

I never even knew horseshoe orbits existed, and that double earth bit at the end is amazing to think about! Now that'd be an interesting sci-fi novel/show

[@ijitorikku5018]

I was used in watching planets in YT but you adding Math into it, making it both harder to understand yet wayyyyyyyy more interesting. It's addicting.

[@Artifexian]

Awesome sauce. That's what I like to hear.

[@maxximmc]

The two habitable moons chasing each other is the first time I've heard of the concept. Then again, it *already* happens with the moons Janus and Epimethius. Mind = blown.

[@sitrilko]

Technicly, Earth too started out as a water world. But yes, the % of water content on early Earth was significantly less than on a outer-system moon might have.

[@macaroon_nuggets8008]

By water world. He means NO ROCK AT ALL (maybe a little tiny core tho.) So no ocean floors just water. Whule earth has ocean floors.

[@jakeariel3974]

@@macaroon_nuggets8008 umm it does not need to be rockless It just have to be REALLY deep

[@macaroon_nuggets8008]

@@jakeariel3974 you are right but I missed my point. The comment (not my reply) said early earth was a water world. It was, but Artifaxian meant water world as moslty composed of water, not the surface fully covered in water.

[@jakeariel3974]

@@macaroon_nuggets8008 oh ok

[@gamingchamp6728]

@@macaroon_nuggets8008 now I’m imagining a water world that looks like an Earth-like water-rock hybrid but has at least half of its water content in the poles waiting for Global Warming to release it.

[@Fetch26291]

I wonder if horseshoe orbit would be possible around a star. A habitable planet and its moon with another habitable planet and its moon, chasing but never catching each other. Would their cultures freak out anytime their moon 'covered' the other world?

[@Artifexian]

I dunno about this, I haven't read anything deal with this set up around stars. But you can of course always handwave these things if the story calls for it.

[@evannibbe9375]

@@Artifexian I feel like the days of darkness every month from having the Sun eclipsed by Jupiter will mentally prepare cultures for getting the sun eclipsed by the other planet that looks like themselves.

[@pufthemajicdragon]

@@Artifexian So I did some looking. There are solar-orbiting horseshoe-orbit bodies. In our solar system, 3753 Cruithne is a big name. So yes, totally possible :)

[@TheWizardGamez]

Feel like that would cause some freaky shit to happen with their moons. Either pulling them out of their orbit causing them to hold a long term grudge and some point cause one of the planets apocalypse. Or would just outright crash the moon if they were in tidal resonance by slowly pulling the moon closer and closer until it got close enough to crash/rip atmosphere or fling out and get caught by the other planet. That being said. A moon isn’t needed for life to form. I would highly doubt that any moon on the size ratio of earths would form

[@Ryan-xo8fj]

Came back to say, something very similar like that system happened to me in Universe Sandbox 2 recently. I was attempting to simulate the creation of planets around a star, when 2 Earth sized planets formed very close to each other slightly closer in than where Earth's orbit would be found. But rather than collide, they almost immediately found a stable horseshoe orbit. It was really cool!

[@lennysmileyface]

How.

[@Ryan-xo8fj]

I was simulating a debris disk around a star (akin to a white dwarf to make it easier on my computer), basically to see how the planets would naturally form, with placing metals, non-metals and ices in different parts of the disk. Two earth-like planets formed near each other, were gradually shifted closer by the other planets, and then it just... happened. I played it for another few thousand orbits, but they continued to work. They were both habitable too, outer one with ~90% ocean coverage, and the other with ~25%, factoring in reasonable greenhouse effect. Although I couldn't really simulate that part, I imagine at their size they would have had comfortable atmospheric pressure and magnetic fields. It was really cool!

[@Phrenotopia]

The amount of detailed explanation is mind-blowing! It really feels like we're getting some very well-reasoned scenarios! Well done!

[@Artifexian]

Cheers, buddy! :)

[@lvr3039]

"Epimetheus approaches Janus from behind", you gotta know how that sounds man...

[@ilikeceral3]

How would the day/night cycle on such a moon work?

[@FiahOwl]

The moon would be tidally locked to the gas giant, and as such its day would be the same length as its orbital period. Tidal locking is virtually guaranteed due to the high mass of the gas giant. One side of the moon would face the gas giant, while the other would never see it. The side that faces the gas giant will experience eclipses during spring and fall (if the gas giant has little to no axial tilt, the moon will experience eclipses throughout the year). In addition, depending on how close the moon is to the gas giant, the side that faces the gas giant may be illuminated by the gas giant at night, perhaps even bright enough to function normally outside!

[@NiwlGames]

if the moon is tidal locked, wouldn't there be a "band" zone where all the eclipses happen ? Also do you know any way to calculate an estimate of the sky degrees that a gas giant would occupy from a viewer on the moon ? :D

[@FiahOwl]

Efflam Mercier Yes, eclipses will only happen on the hemisphere of the moon that faces the planet, if the moon is tidally locked. This is simply because the planet needs to be in the sky in order to eclipse the star. As for calculating the estimate of degrees, use the formula here: en.wikipedia.org/wiki/Angular_diameter 2*arcsin*(moon diameter / 2*moon distance) I believe.

[@enkiimuto1041]

Fun thing about tidal lock on gas giants is that their orbit might not be as long as most people think they are. Io for example takes 1.7 days to go around Jupiter. Edit: thanks for the formula btw.

[@heretical_cuttlefish]

3d bc 5b e3 c4 d5 05 a4 cb df Since the tidally locked side would experience little to no real sunlight beyond what is bounced off of the gas giant, could we expect one side to be colder than the other during the opposing side’s day (that is, when it faces the sun)? Similarly, could we expect it to be colder during that same side’s night (when it is facing away from the sun and is the moon is basically eclipsed), and could we expect these differences in temperature to cause storms surging from one side of the moon to the other?

[@lennysmileyface]

lol I tried to make a horseshoe orbit on Universe Sandbox 2 with 2 Earths but they just end up messing with each others orbit eventually colliding. Could you please make a video on how to make one?

[@jeb_kerm1671]

@KvAT protip: at least for binary stars, if you put planets around them in retrograde orbits relative to the orbital directions of both stars, the stability for those orbits absolutely skyrockets

[@MetricZero]

I'd love to hear what you have to say about moons having moons, and if those could be habitable.

[@enkiimuto1041]

He did a video on that. Basically it sums up on moons having a Rouche limit too. If you have the mass of the moon, you can calculate the Moon's moon. But like he said, probably water worlds (which are not bad)

[@MetricZero]

Enkii Muto Thanks for the info.

[@Omnigeek6]

Moons can't have moons - at least, not for very long. This is because of tides. You may have heard that tides from our moon are slowly making our day longer and causing the moon to move farther away. This is because the moon raises what's called a tidal bulge on Earth, distorting the planet's shape from the normal oblate spheroid. Now, after a given period of time Delta-t, the earth has rotated X degrees and the moon has rotated Y degrees. Since the Earth rotates faster than the moon orbits (earth rotates about 28 times per lunar orbit), X > Y, and the tidal bulge rotates ahead of the moon. This causes the moon's gravity to pull slightly more on the "leading" side of the Earth, creating a torque in the opposite direction of Earth's rotation and slowing it down. By Newton's Third Law, this also means that the moon is pulled forward, causing it to move faster and slowly migrate into a higher orbit. The Earth has the same effect on the Moon's rotation, but since the Earth is much more massive than the moon, the moon long ago became "tidally locked," meaning its rotational and orbital periods are identical and it always keeps the same face towards the Earth. This happens to other moons as well. A very large moon, such as Charon, can also tidally lock the parent planet, but gas giant moons are usually too small to do this. Now, here's the problem. If the moon is orbiting FASTER than its parent rotates or is in a retrograde orbit, then this effect works in reverse, causing the moon to spiral inwards until it passes its parent's Roche Limit and is destroyed. This will happen to Mars's moon Phobos in a few tens of millions of years, and to Neptune's moon Triton in about a billion years. The effect is less severe for small objects held together by tensile strength and not just their own gravity, which is why the tiny particles making up planetary rings can last for a long time. Now, let's imagine a moon of a moon. Because of the way orbital mechanics work, a subsatellite, whether it's a moon of a planet or a moon of a moon, must have an orbital period significantly shorter than its parent (continued).

[@Omnigeek6]

(continued) we can derive this from the formula for the Hill Sphere radius: r ~~ moon orbital distance * (mass of moon / 3 / mass of planet)^1/3. In practice, moons are usually only stable within 1/2 of the hill radius, so the max "stable" orbital distance of a subsatellite is the above formula / 2. We can plug this distance into Kepler's third law: an object's orbital period, if it is much less massive than its parent, is the sqrt(orbital distance^3 / mass of parent) * a constant. Basically, after a lot of algebra the orbital period of a satellite cannot be longer than about 1/5 its parent's orbital period. But recall that the moon's rotational period is equal to its orbital period due to tidal locking, so the moon of a moon's orbital period MUST be shorter than its parent's rotational period. Therefore the moon of a moon will gradually spiral inward due to tidal drag, and eventually either break up or impact its parent.

[@MetricZero]

Omnigeek6 Thanks for the info.

[@DiaSol]

Artifexian you have been a massive influence on my writing recently, so thank you so much, your videos are great.

[@tomh.6261]

Mine too... Edgar is the man!

[@Reid1848]

Without Artifexian, I wouldn't have been able make my planets as scientifically-backed or become inspired to create the systems and planets I have after checking him out. Thank you Edgar!

[@Max-hl3wp]

please make a video about double planet systems, like you said previously about a planet whose moon is the same size that they orbit each other.

[@Barnardrab]

Issac Arthur did a video on that called Double Planets.

[@taemanai5887]

I know this video is older but I've just now found it and had my mind blown. Your two-moon horseshoe orbit civilization idea is fantastic and will probably show up in a tabletop game in my future now. Totally worth subscribing/liking and sharing with my sci-fi friends.

[@Alanzice]

Amazing video as always! Never thought of an Epimetheus and Janus type of orbit for habitable moons. Really interesting! And i'm glad to hear that YT is now kinda financing your studies. Gratz!

[@MoonPrincessYuri]

Your channel is my favourite on KZbin, I love all your videos so much! And this one made me so excited, just lately I've been wondering about the science behind habitable moons, I was even considering asking about it haha. Anyway, thanks for this and keep doing what you do

[@Huntracony]

Have you ever thought about setting up a patreon?

[@kairon156]

Amazing video!! The science fiction geek/nerd in me is blushing at the idea of 2 earth like moons and wondering what their seasons and oceans would behave like. Even if they were some how built in place by some advanced or magical race.

[@jcon5698]

Yay! You turned my question into a video!

[@hedgehog3180]

What would be really cool in a system like that would be the kind of mythology the people living on each planet would build up. Having a system like this would inevitably give rise to some really interesting mythology. And imagine what the first contact between the two planets would be like. I mean going to the other planet would be a project much like our Apollo.

[@ScerythLabs]

I am of course watching this 5 years later, but this has been really helpful for the novel I'm writing. Thank you!

[@renepadilla7104]

Artifexian, just wanted to say thst here is a subscriber who is greatful for your content and the easy to understand way you tell it. Great work.

[@Artifexian]

Thanks, Rene. You are awesome.

[@alexbublea]

Enjoying watching your videos in between my sessions thank you for all the work you put in you're amazing!

[@soton4010]

Your chanel has helped so much! keep going for that pie.

[@TF8ase]

Co-orbital earths would be fascinating. Very excellent video. I always like seeing it take just a little bit further for the sake of narrative.

[@benthomason3307]

There's no need for the planet with the habitable moon to be within the habitable zone of it's star. the planet itself could provide heat.

[@kairon156]

My guess is he was trying to keep it "simple".

[@ferko28]

I've also thought about this scenario, but it would be really bad for the orbits over time, causing the plant to fall into the giant Roche limit.

[@evannibbe9375]

I think the better way to get heat out of Jupiter would be to drop a micro black hole with a mass of 1*10^27 kg and a radius of ~100X smaller than a human hair into Jupiter. This will then cause gas and dust on the inside to spin around it really quickly, giving off enough heat from friction between the spinning particles to push material away from the black hole, thus creating a very slow equilibrium of heat being released as matter falls in. After 1 million years, Jupiter would get hot enough from this interaction to (at Jupiter’s current distance from Earth in our universe) be 50X brighter in the sky than the full Moon. Such a bright Jupiter as this would be able to support habitable planets much further out in gravitationally stable orbits with the category C moons (the captured moons), even with Jupiter itself being outside of the Sun’s habitable zone. The funny thing about this setup will be how the cultures evolve to see with more reddish light and infrared light, and what they will think of the much brighter Sun that is so much smaller and disappears behind the “dull red sun” of Jupiter. The one annoying thing about this design is that we will need to have a way to extract mass away from Jupiter while it is burning to make sure it stays at the same temperature (shunting the excess hydrogen over to a new Saturn-sized planet), since otherwise the temperature of Jupiter will increase 10X over the course of 100 million years (just based on how the equilibrium point for the micro black hole will change as it absorbs more mass).

[@benthomason3307]

@@evannibbe9375 I'm pretty sure that stuff spins around black holes merely for the same reason that planets spin around stars, rather than black holes having some property that magically prevents incoming objects from taking a straight line.

[@japanuke960]

Been waiting for this for a while :) thanks. Brilliant as usual.

[@KristenRowenPliske]

Love watching your videos, even if the math goes over my head! I'm happy to hear you're able to work towards your dream. Study hard and build up your own world! Best of luck!

[@Lucas72928]

Wow, that was a LOT of information! Haha awesome video, as always. I'm really enjoying the moon videos.

[@Artifexian]

Ye, it was pretty dense alright. I wrestling with the idea of doing big dense videos (8-12 mins) or shorter, lighter videos (3-4 mins). Think of this, I will.

[@Lucas72928]

Artifexian Personaly I think dense videos are better.

[@Rationalific]

This is really cool! It's interesting to see how moons need to be spaced, as well as their masses if not captured. Nice!

[@Nayias37]

Working on my own sci-fi story, so I'll definitely be using these soon! Thanks!

[@Seriously_Unserious]

I'm loving these videos. For figuring out the astronomy of a fantasy world, I'd probably do that in the Universim sandbox which would handle the physics and math for me, so I could focus on the world and story building parts.

[@earfolds]

That is incredible news, Edgar. I really wish you the best of luck with your Astrophysics!

[@kbomb1235]

Awesome. Another killer Artefexian video

[@shangewoods5737]

Great video, I was wondering how to get habitable moons for on of my gaseous planets. Suggestion: A video on dual planet systems, like 2 planets orbiting each other.

[@CandyandKawaiiTheFangirl]

4:44 cute, it's a heart. On another note, I found this video very interesting, thank you for making it.

[@CandyandKawaiiTheFangirl]

And you deserve WAY more subscribers for the amazing content you produce.

[@legalliberal3413]

Man you went from 10,000 subs in January 2016, and you're already over 35,000 five months later. As one of the new recruits, I can't say I'm surprised. It's great content! I can't wait for that promised Westeros video!

[@MarkMetEenC]

best video yet! i was looking forward to this one for a while! :)

[@alexhaynes6217]

Thanks for the videos and good luck with your future studies.

[@jgr7487]

it's great to know that YT is helping you to keep up with your super great videos!

[@robspiess]

@10:00 Wait a tic, those Earth-like moons just have the opposite land/water areas! I'm onto your tricks, Edgar! Great video, as always!

[@beaker4311]

congrats on getting the income for the math grinds. good luck. also. before today, i had no idea horse shoe orbits were a thing. i follow your channel for loads of reasons, learning new insane things like that is def. one of em. keep up the good work, mang. ^^

[@CasperVanLaar]

cool man. Supporting your grinds :D!

[@Frankdude72]

Many, many thank yous for this video! Been trying to construct a plausible c. 70% Earth Mass habitable moon orbiting 55 Cnc f. This whole inward migration thing is just the ticket! And it explains the yawning gap in orbits between 55 Cnc f and 55 Cnc d. Brilliant!

[@TheLowArmor]

Waiting for this since yesterday! :D

[@lordilluminati5836]

but how would a captured earth-like objet have a low exentricity orbit?

[@davidk1308]

Other Moons?

[@guaymaster]

Incredible luck and random chance. The universe is basically infinite, there must be a real example somewhere!

[@FiahOwl]

Tidal dampening as it orbits around the gas giant. Look at Triton, for example.

[@lordilluminati5836]

thanks everyone for your answers, I see there are ways to lower exentricity I did not know off.

[@NyoshaM]

Maybe you know that the tidal force locks planets, forcing them to spin with orbital period, so if planet on elliptical orbit, it cannot rotate synchronous because of different speed at apoapsis and periapsis. Orbital energy of the planet converts into heat until spin-orbit resonance is established (like Mercury).

[@Marcsine]

5:22 Aww they're hearts

[@Pherrora]

thank you for posting, very well done

[@matthewtheobald1231]

You don't have to have the gas giant move inwards. For one thing, gas giants actually form close to their stars. Jupiter and our other gas planets were pushed out. Another possibility is you could just make your star larger and so have a bigger habitual zone that reaches to the outer solar system where your gas giant is. Lastly, you don't actually have to have the planet in the habitable zone at all. tidal forces from the gas giant on the moon could warm it enough to have liquid water and volcanic activity

[@MichaelSartore]

Great work man!

[@vazhalaenenyan2252]

I haven't gotten this exited to see a video in a while,

[@graudrakon]

Two quick questions: 1 - What would the rhythms of a habitable moon look like? Seasons, days, years, and "moon"(actually planet) phases? 2 - If you had two habitable moons in a horseshoe orbit what would it be like to be on one of those planets when they switched places? Right off the bat I assume their calendar would be super complicated but would each shift invovle earthquakes, rapid climate change?

[@VegarotFusion]

Well Edgar after watching a few of your videos, you earned my subscription.

[@ellanandi1016]

I love your videos ! Keep on posting!

[@petersmythe6462]

*Triton casually awakening Cthulhu when it reads your rules.*

[@izzomapping7430]

Great! Gotta watch this right now!

[@Madash023]

That horseshoe set up is awesome. It would make for some awesome story settings.

[@Artifexian]

That it would

[@matthewbartlett9222]

Could you please do a video on building the geography of a planet (like islands, coastlines, and mountain ranges) based on plate tectonics?

[@missprizm]

This was awesome.

[@bycoadodbeking1048]

Love your work wish i found u ages ago

[@aldeenithegreat]

ok so just a few questions about habitable moon calendars: 1. Would a habitable moon consider its “year” to be every time it rotates around its host planet, or every time the host planet rotates around its star? 2. Would the former be considered a “lunar” calendar?

[@MrWhiteVzla]

I love watching this video 5 years later with all the exoplanets data we have now. It seems every time we go "I don't think that's possibly," the universe response with "hold my beer." And I mean that related to Giant Planets having to migrate. Most of the exoplanets we have found are inside with rocky planets being all over the place. That data has thrown a wrench into our views of planetary formation

[@jacksonbsleadd]

Please do a video on how day/night cycles and years and calendars would work cause I can’t figure it out on my own

[@546djv]

Time index 7:45, a third option can be that the moon could have formed after the gas giant has migrated to the H.Z via collision between a few large icy or icy/rocky moons collided to form much larger terrestrial moons, like how our moon formed.

[@schlaier]

one of your best videos

[@carterplasek498]

Could you do a series where you build up many planetary systems?

[@aidanokeeffe7928]

I've seen that a lot of your videos are about astronomy and linguistics. Could you do a video on drawing up realistic plants and animals?

[@FunnCubes]

first video i watched.... and subscribed! wow! just wow!

[@whatthefunction9140]

How do you not have more subs?

[@Artifexian]

35K blows my mind. I never thought so many people would be into my little nerdy hobby.

[@ferro9926]

*158k

[@epeemagic]

Are there more strange orbital configurations like the horseshoes? Because that was super interesting. So much story exists in thinking about two civilizations that play a game of cosmic peekaboo with each other!

[@dionemoolman]

How would one make the clouds of the gas Giant itself? Is there a way to accurately colour and compose clouds and storms, for more accuracy?

[@ClaudiaCarranza1]

I offering my assistance with math, if you need it. I am so PROUD of you going back to school. A true inspiration!

[@RobinHilton22367]

Lol @ 6 mins in -> "James Cameron's Pocahontas". In my eyes it was more of a Fern Gully remake ;)

[@kairon156]

wow, I haven't seen Fern Gully in ages. :)

[@Artifexian]

Whatever it was it really was a pretty poor excuse for an "original" movie.

[@Janoha17]

It was "Dances With Wolves" IN SPACE.

[@Francois424]

That was awesome. I wonder about day/night cycles on one of these moons, and bout pro-longed eclipses. Even if Tidally locked with the Gaz giant, it would produce some very interesting cycles... not to mention seasons. ie: " This august, dont expect any 40 Celsius because of the 1 month eclipse... instead ready your warm clothes and central heating as it's going to dip to -20 Celsius for the next 3 weeks" ... You dont what that to happen in winter, lol.

[@marctelfer6159]

@Artifexian - Congratulations on the recent KZbin payments helping out with your maths work before university. I've been world-building using maths/physics on and off for the last... decade or so, but this is probably one of the best presentations I've come across online in that entire time. Quite like Bricka/Geoff's Guide to Creating an Earth-Like Planet (although I'm not sure where that is any more), nicely converting everything into easy to handle "Earth" units, "Sol" units, and so on, but actually giving off an air of excitement about it. I guess that's an advantage of the medium, but, hey, it certainly helps. Good luck in the future, and I hope all goes well with university :) Keep up the good work :)

[@Nonexister1]

Have you ever concidered doing a rosche world style planetary system? In the series htere are 2 worlds balence in the same orbit balanced at the rosche limit. They even get close enough to exchange water from one planet to the other and they share an atmosphere.

[@asadburden1621]

Hey Edgar, I'm building some star systems, but I want to build a star system with two or more habital planets on one star. Thing is I don't know if there would be any complications with gravity or anything. So I was wondering if you could do a video on it! Thanks

[@rebel5141]

OMG. I've watch your videos for ages now, but just realised I'm not subscribed. You're amazing, so keep it up. Good luck with your maths :P

[@Artifexian]

Welcome on board the good ship artifexian, buddy. :)

[@rebel5141]

Artifexian :D

[@languagespotlight24]

So how do you calculate the semi major axis of the asteroid belt that resonates with one of group B moons?

[@pingu4238]

would it be possible for a small planet to get thrown from the inner system to the gas giant's orbit in the system's formation? then when the giant migrates to the habitable zone it holds on to most of its moons including the previously captured one.

[@ViperhawkX]

Fun fact: gas giants' colours change depending on how far they orbit from their star. In the habitable zone, they would be mostly white with a bit of blue, since the clouds would be water.

[@L4g__]

I'm applying to do astrophysics and was wondering where you went and if you would recommend it

[@billysbilbolag2050]

i am realy comfuset about how you get the densety for the "planet maker eqvation", culd you pleace explain this in a future vidio?

[@gavrielsolomons]

I thought I had a really original worldbuilding idea, only to watch this video and see you literally describing my idea 😂

[@ancapftw9113]

Well, my Venus sized moon with one Australia sized continent and many, many islands, which orbits a gas giant around a G5 star sound more plausible now.

[@haemin6505]

wow your videos are awesome!!!!

[@Aodhan2717]

Yay! It's here!

[@Artifexian]

Wait, what's here! :P

[@dime8932]

Or if forms in the habitable zone, or it stays out of the habitable zone but heats it’s moon with tidal forces, or it’s moon has a thick atmosphere with lots of radioactive elements, or it has a habitable subsurface ocean… my point being there are more ways for a moon (or a planet for that matter) to be habitable than just being in the habitable zone

[@loganplourde886]

Could you make a video about habitable/earth like planets that orbit different types of stars and how that would change the appearance of plants and the sky based on the type/color of light that the star produced. The plants on a planet orbiting a star that produces a lot of ultraviolet light would have dark almost black leaves and the sky and atmosphere would have to be composed differently from earths to protect the inhabitants and the sky would be a different color because of this (atmospheric composition and star type)

[@MadMargaretGaming]

That final scenario could involve a giant moving inwards and capturing two potentially habitable worlds

[@novatheumbreon1364]

Awesome!

[@smivan.]

Fantastic news with the youtube payment!!! I wish you good luck in your learning!

[@Artifexian]

Loving it so far. Math for the win!