The Trouble with Terrestrials

[@dionemoolman]

Remember, planets can be denser than iron for a simple reason: Gravitational Compression. The Earth is 20% denser than its material makeup conventionally as the gravity crushes it into a smaller volume.

[@alphasaith8349]

That moment when you accidentally make a brown dwarf that houses one of the most feared species your universe has ever seen. Oops.

[@masicbemester]

Bruh

[@monhunterz5430]

That can still work if you play it right, what are the characteristics of this species?

[@Kromiball]

2 years ago

[@pentelegomenon1175]

maybe it's like that story Dragon's Egg, it could work

[@wallabra]

The dwarf is brown and has E. coli

[@aaronwest1055]

It's not a matter about whether or not I like what I see, but whether or not I can understand what I see.

[@parthiancapitalist2733]

Aaron West ez

[@dionemoolman]

6:08 Well actually yes. Its high density is due to the extreme gravity compressing the material into a smaller volume. You can see this in Earth’s core, where the density is 13 grams per cubic centimetre, which is twice that of iron. The planet graph accounts for that.

[@parthiancapitalist2733]

One of my planets is 3.5 g/cm^3, and I named it Lucy. The density of diamond is 3.5 g/cm^3, so I mathematically created Lucy in the Sky with Diamonds

[@parthiancapitalist2733]

In other words, I made astronomical acid

[@diamonds5554]

*nice*

[@user-jr7ww2gf1h]

Beatles yee

[@geeep7996]

Lucy in space that has the same density of diamonds

[@osotanuki3359]

Or, "Lucy in the sky's a diamond"

[@DougAdomatis]

Edgar, I want you to know that I'm using your videos to teach planetary astronomy to high school students. I have tasked students with designing their own habitable exoplanet. We started with "Formation of a Solar System" and "How to build a Star". Then I assigned each of them unique star mass. Now we are watching this video. Next we will watch Build own Terrestrial Planet followed by your videos on orbits. At the end of the course students will present their designs. Thank you for producing videos are high quality, scientifically accurate, and entertaining.

[@WarHammerGmer]

Dude, you should make more videos on just physics, astrophysics, and astronomy. I'm loving these so far. They're really well done and you have a great voice.

[@Artifexian]

CornOnTheCon Thanks CornOnTheCon. Kind words, but I think i'll leave the hard science to the big guns of youtube education. Minutephysics, Sixty symbols, Deep sky videos etc. They do a way better job than I could ever hope to do. :)

[@KaaSerpent]

OK. I've now watched all your videos after subscribing. I have a question. What do you do "in real life"? Just curious, because you seem very comfortable talking to the camera, you draw well, and you've got a good grasp of the science, as far as my own limited understanding of it goes. (Not looking for details or anything creepy. Just generalities. :)

[@parthiancapitalist2733]

KaaSerpent he does KZbin

[@wallabra]

@@parthiancapitalist2733 mind=blown

[@edthoreum7625]

He is a manicurist 🎯

[@nickcol13]

i heard you on Vsause2 yesterday, and have now just finished watching all of your videos from start to finish. Subscribed! Fantastic work Artifexian!

[@Artifexian]

Why thank you! Welcome aboard. Hope you enjoy life abroad the USS Artifexian. :)

[@mousermind]

Great. Now simple words like "sauce" are being butchered online. -_-

[@KlaxontheImpailr]

3:08 this actually makes sense because you're taking the same amount of matter and spreading it too thin

[@parthiancapitalist2733]

Eric Southard yep, always use the graph before making any planet. I once tried to make a water world, and it was 10.2233 gm/c^3 I was too stupid to look at the graph. I had to edit all the equations that used that density. Now, it is 4.9907 gm/c^3

[@zrspangle]

@soviet hoehavetoe I assume it wasn't a pure H2O planet

[@haydnstrunga573]

Artifexian You are possibly the best youtuber I know of please don't change!

[@kalez238]

I learned a ton of new stuff just now. I love learning new stuff! Keep on amazing me!

[@Artifexian]

Cheers *****, hope to continue amazing you in the future :)

[@jameslee9958]

Hi I've really been enjoying your series so far. If I could suggest something it would be that you add a numbering system to you're world building videos-it'd give more of a sense of chronology. Keep 'em coming!

[@Manibe37]

Dude your channel's concept is awesome! I have always wondered about planetary systems possibilities!

[@noodboy4633]

1:20 by this definition mercury isnt a planet because it only has 0.055 earth masses...

[@kaanaknc5039]

Neither my English nor my math was prepared for this.

[@tangerian319]

I was creating a world back in the day that was rich in copper oxide in soil composition at an axial tilt of something like 30 degrees or something. my thought was that the soil would be mainly greenish in color, what is your views on this theoretical planet?

[@rowbot5555]

You still remember this project? If so, you'd probably need something wacky to happen during the planets formation, perhaps a nearby supernova or some other kind of Celestial event could do it, but it'd be hard to get that over a large portion of the planets surface for long. Maybe a high copper asteroid hits the planet in a dino extinction similar event, and intelligent life develops shortly after to enjoy it

[@TheRavenLilian]

As a story teller and an astronomy and math nerd I am delightfully chewing my way through these videos.

[@JayFolipurba]

Hah! I put the mass of my first star to be 1.101650415 solar masses. Now check out the luminosity! I think it's rather leet... xD

[@Artifexian]

Always round to the nearest leet :P

[@parthiancapitalist2733]

The power to round is the power to destroy. Imagine loosing just 0.000001% of the mass, things could turn out very different than you want

[@cosmopoiesecriandomundos7446]

2:49 ok but what's the minimum for Earth?

[@Nathouuuutheone]

??? What was the question? How is it applied to world-building? What is this video even about??? I learned some cool stuff but am left wondering why I watched it and why it didn't really say what the "problem" was and why it mattered, and didn't put it in the channel's "world-building" context at all. Very confusing even though the specific content is well explained and super interesting.

[@dave493010]

Really well-done, informative video, thanks man! I learned some new stuff there

[@Artifexian]

Cheers Dave. Thanks for watching. :)

[@Unikraken]

A video series like this on orbital mechanics would be the bomb.

[@kalarin2474]

I really enjoy your channel! Just a small thing, at 2:15 you say super earths are between 1.5-2 earth radii, though the chart states 1.25-2 earth radii. Keep up the great work!

[@Artifexian]

Whoops! Mispoke...didn't pick that up in editing. When in doubt go with the NASA chart :P Thanks for the correction and glad you enjoyed :)

[@user-is2zv4sc6y]

Graphs get kinda tricky when logarithmic scales are involved.

[@Unputonombre84]

... And all I wanted to do was to tell a little story. Now I have to spend a year studying physics and figuring out how all of this will make it into the story... Sheeesssshhhh!

[@Trufles1234]

5:27 48.5,48.5 and 6.5 add up to 103.5 not 100

[@julesmcbride2692]

This is like minute physics but with hard facts. I love it.

[@Gleanix]

I just stumbled upon your channel and I love it! You have really great content. Keep up the good work!

[@Artifexian]

Will endeavour to do so :)

[@rayrerej9630]

In light of your recent podcast discussion: I'm not blind, but I'm having a lot of trouble reading and correctly using the graph you show here. For me, I think it'd be easier to have this information displayed as ranges of g/cm³--for example, is 2 g/cm³ a terrestrial or a water world? Is it a gas planet? Is it an improbable density for any celestial body? Calculating g/cm³ should be fairly doable for people with screen readers as long as you provide the formula in the description, and I'm finding it a lot easier than holding a ruler up against my wiggly touch screen devices.

[@unvergebeneid]

How awesome would a pure water world be? Just a gigantic drop of water, hanging in space :)

[@myguy8007]

Sadly if it where true it's mass would condense its core into a icy ball which would slush around and could possibly, like Uranus(blush) and Neptune, generate a magnetic field.

[@unvergebeneid]

Angry Scottsman I'm not so sure about that. Depending on temperature, water turns into ice VI or VII at something like 100 MPa to 1 GPa (ten times more if the "core" of water world could be a couple hundred degrees hot which I doubt). Now on Earth, a water column of the size of 1 Earth radius would easily exceed these pressures (I get something like 60 GPa). But a planet made completely of water would have a much lower gravity. Assuming Earth surface level density of water (yes, quite the simplification, I know), my admittedly very back-of-the-envelope calculations get me to a maximum pressure of roughly 100 MPa for an Earth-sized water planet. And nobody's saying the planet has to be this big. A Mars-sized world would have a much lower pressure at its center so even some compression could be dealt with without turning the core into ice.

[@cyndie26]

I remember commenting on another video of yours about this topic, but I remember seeing a video of Jacksepticeye playing with Universe Sandbox 2. He changed the mass of Earth to that of 1,000 Jupiters and Earth turned into another sun. Does this mean that if Earth were to somehow accumulate that much mass, it would become a gas giant and fuse hydrogen, that if it always had that amount of mass, that would happen, or is it because the software has different sprites for objects of different masses?

[@seraphina985]

Solar mass Earth would probably have almost no Hydrogen near it's core due to the massive quantities of molten rock and iron sinking to the core as they melted from the heat of the compression. It would have considerable amounts of Hydrogen 1,000 times Earth's ocean mass worth of water is quite a lot of H but it would likely be mostly far too far out from the core to actually have the heat and pressure to fuse the Hydrogen there. In fact it would likely act like you would expect a 1 solar mass stellar remnant which is no longer undergoing fusion to behave ie > Neutron Star > Black Hole. The only reason 1 solar mass stars don't do this is that they blow away such a huge portion of their mass during the final stages of their life.

[@amfvideos6810]

1:30 this notion has been disproved with the discovery of mega earths such as Kepler 277b which is 80 earth masses and yet not gaseous

[@ErnestJay88]

well, when the planet form, it didn't have so many metal and rocky building material, so it ended as "Gas miniature" (reverse gas giants)

[@zxana]

Artifexian i was wondering if you could do a bit on a Westeros style planet that has summers and winters that last 5-11 years each but could still harbor life from what i understand the planet would have to have a dual orbit around a brown dwarf at a distance far enough away that it wouldn't be visible and a primary star that would be slightly larger than our star but far enough out that it would take up the same % of sky

[@Quiltfish]

Remember, two turds of the time the planet isn't earthlike. I kid, I kid, I love your content!

[@Sabersonic]

Interesting maximum limits of plausible terrestrial, Earth - like planets or "rocky" worlds as we in the States were taught in Elementary if I recall correctly. Also interesting that there is such a possibility as gas planets near the Earth and Super-Earth mass scale but on the two - thirds side of the density scale. Probably would classify them as Dwarf Gas Planets or similar, or did you already discuss this in one of those Gas Giant videos previous....? Still informative and potentially useful, though I have the feeling that the greater detail of such terrestrial surface features like tectonics and hydrosphere would potentially involve similar (and as far as that comet mission suggest, incomplete) equations that'll make a person's head explode as the one featured in this video. Thank goodness for graphs indeed!

[@Artifexian]

Yes they would definitely be gas dwarfs. In Graphs We Trust!

[@Sabersonic]

Artifexian Oh good, my comment did make it through. When I first submitted it via the KZbin App on my android, it said that comments were disabled just after I hit the submit button. And when I tried to see the comments on the kindle, several were missing despite the comment count. Odd.... In other news, I finally saw that Interstellar film. Would be interesting to know your thoughts on it in a future video or something.

[@firefectschannel362]

how did 1.22 turn into 6.74 exactly?

[@parthiancapitalist2733]

The density of earth is 1 earth density, or 5.52 g/cm^3, 1.22x5.52 is 6.74

[@lasarith2]

5/1.6 (square) =1.953125 /1.6x 5.51 = 6.726g

[@natheniel]

I just now found out that this old logo is just Artifexian in Ogham script!!!!!!

[@WSing]

Maybe it's a silly question.. I'm not that well versed with math and the equations you're using. But how is the density of a planet calculated? If the basic equation is density = mass / radius^2 and I use the following numbers of - Mass: 1.8 - Radius: 1.3 g = 1.8/1.3^2 = 1.0651 (density) but what calculation to make next? Sorry for asking a silly question, again, im just not that well versed with math :(

[@Artifexian]

There is no such thing as a silly question. So first of the equation is M/R^3, not M/R^2. So you'll get 1.8/1.3^3 = 0.82 = density relative to earth. So simply look up the density of earth on wikipedia, (spoiler - its 5.15 g/cm^3) and multiple that value by the value you got from the equation. e.g 5.15 g/cm^3 * 0.82 = 4.52 g/cm^3. Therefore your planet has a density of 4.52 g/cm^3

[@WSing]

Artifexian Ugh, of course.. how silly of me.. thanks for your quick reply though!! I love your video's! very inspiring and interesting!!

[@Artifexian]

No problem :)

[@davidpo5517]

I love your videos and happily subscribed!!! You put things together so well! Seeings as this series is about world building, I thought I'd ask. Eventually, would you consider doing a video about the plausibility of either a habitable hollowed out planet or planet with a strictly subterranean atmosphere? My initial thought is this: you mentioned in earlier videos that type M stars are very long lived but in order for a planet to be warmed enough it would require being so close to the star it would be ravaged by stellar winds and storms. This wouldn't prevent the development of life deep underground, though, would it? Especially if the planet has a strong magnetic field.

[@Artifexian]

This is will come up in the next 2-3 videos. I'll leave you with that teaser, stay tuned :)

[@davidpo5517]

I await eagerly!! Thanks ever so much for the great explanations and prompt replies!!!!

[@SkittleflakeKitty]

what is the music

[@pentelegomenon1175]

This seems perfectly understandable, when designing a fictional planet you can work out its density by means of a simple calculation involving radius and mass, and this will tell you far more about the planet's general nature than radius and mass alone thus being a superior indicator of its resemblance to Earth, and simple charts can tell you where reasonable densities exist within the range of reasonable mass and radius.

[@natheniel]

With that boundary, surely the relationship between M and ρ can be reduced to a simple logarithmic equation.

[@InternetSandman]

I've been really curious about exoplanets, in particular what will eventually happen when humans start to look for candidates for colonization, and your videos are awesome to watch, learning lots from you. Keep it up!

[@Artifexian]

InternetSandman Cheers buddy :)

[@michagrill9432]

Your visualisation is so cute and fun :D

[@thirdcoastfirebird]

I am having some trouble with making my planet I am finding hard to understand where the red number comes from at 7:03. Can anyone help me understand that?

[@lasarith2]

5/1.6 (square )= 1.953125 /1.6 (1.22) x 5.51 = 6.726g

[@lasarith2]

Also the gravity to too high (1.95 ) you want to keep it below 1.5 G

[@Actur86]

Ok, but what would the gravitational pull be on the surface of a planet with 1.6 earth r and 5x earth mass?

[@Actur86]

I mean. If we're talking world building and the people/ creatures on the world are evolving to handle a gravitational pull 5x that of earth I don't think we recognize those species.

[@HouseholdWheel]

the creatures on the planet would probably be small but muscular, wityh just the right bone density to hold them up. Also if they came to earth they would be super strong due to the much weaker gravity.

[@oneofmanyparadoxfans5447]

So my world with 3 Earth Radii and average gravity of ~2.9G with a somewhat low density and a mostly silicate design isn't feasible in a realistic sense? Well... I've modified Earth's geography slightly in this alternate universe I created, I think I can alter physics.

[@lasarith2]

You can have a 3M planet but radius should be 1.54 , 3M 1.54R G1.264 D 4.525g anything above 1.3 G you will being to suffer heart problems to 1.5 G.

[@oneofmanyparadoxfans5447]

@@lasarith2 It's been a couple years since I last saw this video, can you label the variables so I can make heads and tails of this?

[@lasarith2]

@@oneofmanyparadoxfans5447 M mass, R radius, G gravity, (g density, grams cm3 ) to stay healthy at lest 1.3G ((1.5 max .

[@lasarith2]

@@oneofmanyparadoxfans5447 3/1.54 square^2 = 1.264G /1.5x 5.51 = 4.525g

[@oneofmanyparadoxfans5447]

@@lasarith2 Thank you.

[@colleenforrest7936]

If only the IAU definition of a planet was based on this type of math. It takes a wordsmith to get a definition correct. Good job!

[@majkatrebaticka2957]

Say "the planet Has a Huge mass" but the m is not here...

[@danoodledooddle]

Awesome! Love your videos! Do you plan on doing any videos of worbuilding on a planet? Like plate tectonics, formation of continents and mountainranges, rivers and windcurrents? Would be cool! :)

[@cryptid-artha]

Question - I want to do a bit of world building for the world my webcomic takes place in. What would it take to have a habitable moon with earthlike conditions orbiting a gas giant?

[@singadorito7802]

Kepler-90: *Laughs in No Terra Planet*

[@NikodAnimations]

Assuming the M/(R^3) equation is perfect (which it isn't), then thr relationship would be the cube root of M being R

[@XLHeavyD999]

After watching this very interesting video i realy need a paracetamol. Twice the mass of earth ;)

[@TheUlquiorraCifer]

There is probably a super-earth much much larger then earth out there but it would have to be insanely dense and it would also have such extreme gravity that we would need insanely advanced levels of technology to live on one.

[@ClashBluelight]

so if i make a 1.6 sized earth and give it a 10 times mass i can have a max gravity earth? that should have 16 times gravity. would it be possible for life to evolve in these circumstances?

[@briannasellers5508]

Actually Terrestrial planets come in 3 forms as of Dwarf Planets, Terrestrial planets, and Water Giants. Now once at 10 Earth Masses instead of gases it would actually take in a lot of Liquids, only until about 24 Earth Masses would it become a gas planet

[@marten_mkklsn]

I know this is a pretty old video, but I'm having problems with the graph. If I wanted to graph say a planet with a mass of 0.2 and a radius of also 0.2 I will have an earth-like composition according to the graph. However, plugging the values into the equation gets me a density of 25x that of Earth. How can this be possible? Am I reading the graph incorrectly?

[@faceofsarcasm4947]

In the equation, what is k? I know it's some constant but what? I have to know!

[@MathewStone1]

Wow. Most science videos always leave some annoying unknown but this really wrapped it up with a full explanation. Thanks

[@maryy1370]

I am NOT tech savvy, but I'm trying to make a planet. Take pity on me and tell me: What are the computer programs you use for all your modeling? Like seize comparisons and the graphing, and for plotting, or weather patterns. They're all visual formats so they're drawn, but what are the programs? All I've found is freehand drawing or math graphing xyz, not letting you overlay things on the density chart. Please take pity!

[@vulthuryol8051]

So, what would be the density of a waterworld composed entirely by Kevin Costners?

[@SuperMarioGamerBros]

Quick dumb question.I n the video you called 0.0001 not point not not not one however were I am from I would call it zero point oh oh oh one. So my question is, were do you live that you call it not?

[@VoidUnderTheSun]

SuperMarioGamerBros You mean "nought" instead of "not"? I'd say judging by his accent (and I am in no way an expert of accents) that I'd say he *probably* lives in Northern Ireland. Or even the Republic of Ireland...

[@Artifexian]

UnderTheSun I live in the republic and my natural tendency is to say "nought" for zero.

[@VoidUnderTheSun]

Artifexian It was actually SuperMarioGamerBros who asked about saying "nought." I too use nought.

[@ChrissieBear]

+SuperMarioGamerBros Nought is what zero is called in The UK. (in maths, at least.)

[@HappyBeezerStudios]

And we can call it o, as in "oh"

[@Zivodor]

So in the formula you gave what are k1-3? Are they a constant for every planet?

[@Artifexian]

***** For every solid planet up to 20 earth masses. Here's the paper. Check it out for more info. I'll throw the links in the description as wellarxiv.org/abs/0707.2895

[@deathracoffee]

Hmm... I found this: arxiv.org/pdf/0707.2895.pdf This is an extended version of what you've added and there is a table, where k1-3 are said to be: for Fe(α) [modified-polytropic EOS] => k1 = -0.209490, k2 = 0.0804, k3 = 0.394; for MgSiO3 (perovskite) [modified-polytropic EOS] => k1 =-0.209594, k2 = 0.0799, k3 = 0.413; for H2O (ice) [modified-polytropic EOS] => k1 = -0.209396, k2 = 0.0807, k3 = 0.375. So, my problem is... I don't really know, which of these I should use to sample world. Take the Earth - is it MgSiO3? What is the most common Earth-like k1-3 value?

[@Madash023]

So I'm curious how you would define a planet in general. I believe the current definition states that it must have cleared its orbit of debris to qualify, but then wouldn't the Greeks and Trojans disqualify Jupiter as a planet?

[@Artifexian]

TheKirov099 Yes...technically. But Jupiter is the most gravitationally dominant object in/around its orbit...so although the greeks and trojans are technically orbital debris they are in Jupiter's control. And so we think of Jupiter as planet.

[@HouseholdWheel]

Are there any rules to naming planets? Or can they be called anything? should planets be named after Gods? like the planets in our solar system being named after Roman gods

[@stephenmcbride1094]

Does anyone perhaps know what the different variables represent? I mean for this: log10Rs=k1+1/3log10(Ms)−k2Mk3s

[@etherloc7109]

seagerexoplanets.mit.edu/ftp/Papers/Seager2007.pdf

[@imienazwisko6527]

Terrestrial planets are planets that have soild surfaces, but may have some liquid material on the surface.

[@quentenwalker1385]

I cannot download this video, although I have downloaded the rest of this wonderful series - many of them already rewatched. Any help please?

[@thesrilankanguy3652]

I"m making an alien planet and this is really helping. I legit made the planet 8 light seconds in diameter. It wasn't even a gas giant, just a normal terrestrial one. Though I am still confused on whats the largest a super earth can be.

[@NikodAnimations]

10 Earth masses and it will be a gas giant

[@ajhigginscomposer]

1:17 not point one?

[@angus4459]

+Artifexian Is there a version of the chart you used un this video that goes to the bottom of the Dwarf planet range?

[@rollerroadstar8003]

This graph is confusing me. The little lines in between the whole numbers are weird. It's like they're different in between each pair of whole numbers

[@Luka1180]

Apparently it's beause they are on a logarithmic scale to make it more convenient. Doesn't appear convenient, sadly, for people who don't know too much math. Also annoying that there is no editable version of the graph from Sara Seager's team that we can add our own planet points into.

[@diarmuidbalfe7264]

This is probably a stupid question but what do the points on the axies of the graph represent?

[@olegshevchenko5869]

Well the legend is in the left upper corner - blue triangles for solar system planets, and the other ones are exoplanets. Just so that we could compare to the real-life examples

[@diarmuidbalfe7264]

Oleg Shevchenko I meant how the points along the axis seem to be 10 times bigger than the one that came before it or something, I'm not too sure

[@olegshevchenko5869]

+Diarmuid Balfe it's called logariphmic distribution. If units having large values are less in numer, you scale the axis so that lower values have more space than the higher ones. it's convinient that way. if that's what you're asking about

[@diarmuidbalfe7264]

Oleg Shevchenko Right yeah I get you know :-) I don't know why I didn't think of that

[@Luka1180]

@@olegshevchenko5869 I wish we just had an editable version of Seager's graph, so we could input our own two values and have the point (the planet) apear on the damn graph, but the graph isn't available online anywhere. I believe it's a GNUplot or Matlab (most likely matlab, since they used matlab for other stuff in their research and also provided a free code for calculating the internal composition/structure of planets.)

[@dionemoolman]

I searched, and the density of the Earth's core is 13 grams per cubic centimetre. Since the density of iron is no more than eight grams per cubic centimetre, how is this possible?

[@pyrania6828]

Gravity compresses material towards the core.

[@lostn65]

You are smart and a fine artist. I find your videos entertaining.

[@EnergyKnife]

+lostn65 I don't think he drew this

[@theresamay4280]

+EnergyKnife Then who did?

[@EnergyKnife]

+Heather Stranger I don't know. Those look like a woman's hands though

[@theresamay4280]

+EnergyKnife Erm...not really.

[@EnergyKnife]

+Heather Stranger Yes they do. They are thin and have very long nails. They may be male, but they look female

[@rollerroadstar8003]

How do you divide density by density and get density equals mass over radius cubed?

[@Релёкс84]

Wht are you trying to say exactly?

[@0ijrc]

Artifexian, how do you use the graph??

[@parthiancapitalist2733]

Junior Carruthers just use two rulers

[@0ijrc]

Creeper Pro what do you mean?

[@0ijrc]

Is it like log 10 or something

[@Luka1180]

@@parthiancapitalist2733 That's a horrible idea. What if I want 2.0847484 for one number LMAO?

[@Luka1180]

@@0ijrc I agree, this is also confusing to me. Is it logarithmic or not? Or are there just 1 radius at each line to the left, with it incrementing by 1 each time there's a line?

[@evanw.150]

The music is so calm

[@stiqula]

YOUR NAILS o.O

[@Artifexian]

I'm a guitarist. It comes with the territory :s

[@purple_purpur7379]

Could one make a habitable natural satellite of a gas/liquid/ice giant?

[@johnhooyer3101]

I've been watching a ton of your videos and only _just_ realized that "not" is your dialect's word for "zero." I'm going to have to go back and re-watch _everything_ now.

[@chevtothemax]

What he is saying is naught.

[@ianmoseley9910]

John Hooyer It is 'nought' and it is standard Eglish, not dialect

[@holaamigo3399]

how about higher density metals such as mercury and gold

[@bobhallway5507]

+artifexian I'm lost how did 1.22 become 6.74g/cm^3?

[@Thompsoncorv]

multiply 1.22 by the density of the earth

[@syhsreybse]

The density of earth is 1 earth density, or 5.52 g/cm^3, 1.22x5.52 is 6.74

[@MaTheRaptor]

No, seriously, how would you calculate the percentage of surface land of a planet against water area? Because until now I've been eyeballing a 80-20% water-land but I'm sure if I was to double check with measurements it'd be way off XD

[@rowbot5555]

If you are still looking for the question, low geologic activity means more flat areas and larger shallower oceans, I don't know the exact ratio though, also lower metal concentration means flatter as well

[@MellonVegan]

Totally off topic: May I ask what area you are from? I am just very interested in accents and dialects and want to know, if my guess is right ;)

[@Artifexian]

I am from Ireland or more specifically the west of Ireland. Did you guess right?

[@MellonVegan]

Oh no, I was so off :D Reminded me of some London accent I once heard. But well, it's the same continent, so close enough ^^

[@darkmelvinperezstarx8978]

Can anybody explain Log10Rs=k1+1/3Log10(Ms)-k2Ms^k3?

[@darkmelvinperezstarx8978]

What's k1, k2, k3?

[@parthiancapitalist2733]

Log of 10... Something like that. K is for ehm... ... The way the ratio of.. Density I guess maybe. Sorry idk

[@daniel_rossy_explica]

@@darkmelvinperezstarx8978 depends on the material. If you look into the paper, there is a table that lists them, along with some other values.

[@Banana-senpai]

This video has some good ideas about terrestrial planets and how to create believable ones, but it has a wrong focus. Of course you can't just plug any number in the terrestrial range for mass and volume. However you call them, terrestrial planets or super earths, come from the premise that they are rocky planets, so they are bound to have a more strict correlation between mass and radius. In your first example with 1.9 earth radii and 1 earth mass makes a tiny gass planet, which is impossible. I don't understand the purpose of this video

[@km5405]

love your content, very very much in depth about world building and things like flag building :D

[@BigGamer2525]

Uhhhhh I'm pretty sure that the volume of a sphere is 2/3*pi*r^3, not simply r^3

[@Artifexian]

BigGamer2525 I showed my workings as to how the r^3 value is achieved. First off the volume of sphere is 4/3*pi*r^3 not 2/3*pi*r^3. Secondly, by getting rid of the any constants (4/3 and pi) one can quantities relative to another object. Example: the sun has a radius of 1 solar radii and a volume of 1 solar volume. A star with 1.5 times the suns radius will have (R^3) a volume of 3.375 times the suns volume. Hope that cleared things up.

[@BigGamer2525]

Artifexian Sorry for the misunderstanding, but thank you for your wonderful reply! Great video regardless.

[@Artifexian]

No problemo :)

[@The_WhitePencil]

now im confused, is it a not or a zero? HAVE I BEEN WRONG ALL THIS TIME?

[@ianmoseley9910]

WhitePencil Nought or zero - same thing , different verbal habits. Some would also use letter O for zeroes after the decimal point.

[@Inhabitantgame]

Hey @artifexian, I just want to let you know that we created our first video to showcase the game we working on. I would also want to thank you because without your channel some of the logic we have built would be impossible or at least unlikely. We have added you to our credits menu - have a look kzbin.info

[@Artifexian]

Amazing! Just watched the video...looks very exciting. Keep up the good work

[@Nicoder6884]

I understand what you mean. We should stop using the term "terrestrial planet", and replace it with the term "rocky planet". EDIT: Even then, what if we had a water world?

[@g-rexsaurus794]

Most of it would still be rocky. Or icy.

[@johnterpack3940]

It gets even more complicated when you try to account for gravity. I consider "high gravity worlds" the realm of soft sci-fi for the simple reason that civilization can't exist beyond a certain limit. At some point, you can't build anything. And I'm betting gravity doesn't have to get much higher than Earth's before it becomes impossible to reach space. I mean, the Saturn V rocket was built with a certain bill of materials to be strong enough to hold itself up and withstand the rigors of launch. Double gravity and you can't build a Saturn V. The materials needed to hold it up would be too heavy to launch. Even simple things like houses couldn't be built if gravity got much higher.

[@oscarcarmenwarnstrom9122]

You made Mars too smaller than the other 3 terrestrial planets.

[@natnew32]

Mars is actually ok is size vs. venus/earth, mercury is the real culprit.

[@livedandletdie]

+oscarCarmen warnstrom Mars is 2/3 the radii of Earth, Venus is 8/9 Radii of Earth

[@parthiancapitalist2733]

The Major also, Mars has a lot of iron, so why doesn't it have more density?

[@thetitanian5544]

surface iron

[@CamoCam0]

If you ever plan on recreating a fictional system can you have a look at the one from the film Pitch Black? Love the channel, you just got a new subscriber :)

[@Artifexian]

Welcome aboard! Glad to have you. Ye maybe sometime in the future. I've taking note of that idea...its on THE list :)

[@TheLoveBomberz]

How does this help us with worldbuilding ?

[@Hartono25277]

I like your drawing