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Being an engineer and someone who hates hot summers and frigid winters, and someone who really likes the Rocky Mountain view, I can not help but wonder if we humans could get to design a whole new planet instead of just accepting preexisting ones, and our object being designing a planet that hosts about 1~2 billion people with nearly 100% of the landmass looking like the best part of the US, e.g. California or Montana, what would be the appropriate design procedure? For example, given the following constraints (These applies to every square inch of the new planet's land mass, excluding very high mountain ranges positioned strategically to intercept moisture)

  • Surface gravity exactly 1g.
  • Surface air pressure exactly 1atm, air composition 78% Nitrogen, 21% Oxygen, water vapor varies according to weather.
  • Day exactly 24 hours, year exactly 365 days, no leap year funny business.
  • Distinct 4 seasons, with minimum temperature no lower than -10 Celsius, maximum temperature no higher than 25 Celsius.
  • Yearly precipitation ~1000mm, with no less than 300mm in winter.
  • No hurricane, no tornado, maximum airspeed with respect to the ground within 20 m/s within the first 10 km from the ground up.
  • Tectonic activities to combat weathering but no changing landscape, no earthquakes, no continental drift to distort landmass shape, no volcanos.
  • Lime rock or granite bedrock, aquifer layer around planet underground within 50m from the surface.

and if I throw in some non-quantitative request such as fertile soil, good mountain view, good beach, plenty of seafood around the shore, is there a possible rough outline of how to decide all the factors?

For example, the stable year and day length may require a moon, a small inner planet and a massive outer gas giant to stabilize the orbit, axial tilt, and rotation speed in billions of years, although the initial value of these can be set arbitrarily. The landmass distribution and the seafloor shape may determine the ocean current flow pattern, precipitation and wet greenhouse effect and how much cloud there is, the mantle and crust composition and dynamics may influence tectonic activities, the temperature, precipitation and tectonic activities ultimately decides whether the carbon cycle is stable and at which level it is, even the amount of thunderstorm lightning might have an influence on how much nitrogen is converted to natural fertilizer and thus the stability of the ecosphere. That's a lot of numerical characteristics determined by just a few free variables.

The planet can be bigger or smaller than earth, the distribution of landmass, and the associated altitude is completely free, although for a reasonable assumption say the total distance variation from the gravity center to any point on the surface should be within 2% of the mean planetary radius.


Think of the planet as an intricate clockwork with gravitational potential as its spring. When the planet is pristine, the spring is wound to the tightest. Over the years the spring unwinds, the little brass bearing of its tiny gears wear out, its metal grows fatigue with each acceleration and deceleration of the second hand, but the clock always shows the correct time with a very narrow margin. That's what I'm asking similar of a planet, a correct design that ages correctly, instead of Earth, which is clock that shows the noon to be noon now and midnight to be midnight as of this moment, but will show noon to be midnight and midnight noon a mere couple of hundreds of millions years from now on, because its internal gears is gradually knocked out of place by its own force.


If the planet's spin is slowed by constant rubbing of wind and sea, maybe the other bodies in the system could constantly replenish the Earth analog's angular momentum by giving up some of their own?

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  • $\begingroup$ Welcome to the site! Off-hand, I'm going to say this luxury world is only possible in cyberspace. Your tectonic requirement, for example, combines qualities of a warm, living planet with a cold, dead planet. As for the question: I'm not sure what you're asking. Are you looking for a way to make your luxury world viable according to science? Trying to determine where and how to start a worldbuilding project? $\endgroup$ – Frostfyre Mar 26 at 12:27
  • $\begingroup$ @Frostfyre I'm asking whether there's a set of parameters of initial conditions of a planet that allows human to live on its surface without trouble indefinitely without an appreciable change of its comfort. $\endgroup$ – Meatball Princess Mar 26 at 12:33
  • $\begingroup$ "A planet" being any arbitrary world, or specifically the one you described? $\endgroup$ – Frostfyre Mar 26 at 12:35
  • $\begingroup$ What's the rationale behind the need for some of these exact values? Earth's gravity varies by less than a percent over all location on the surface, too little to notice, but it's not exactly 1g everywhere. Leap years are annoying, yes, but how do you feel about leap seconds? These have been added to the clock dozens of times by top timekeeping scientist, and I highly doubt that most people even notice. Seems like these two requirements are just precision for the sake of precision, and wouldn't materially affect anyone living on the planet. $\endgroup$ – Nuclear Wang Mar 26 at 13:39
  • $\begingroup$ It would be easy to get these conditions in a spin gravity habitat [1]. It would take way less resources to pull it of and the environment would be fully customizable, since you build it from the ground up. Are you willing to except some coriolis effect and a sky that curves up (montains would make that less opticallt severe)? [1] en.m.wikipedia.org/wiki/O%27Neill_cylinder and youtu.be/gTDlSORhI-k $\endgroup$ – TheDyingOfLight Mar 26 at 13:45
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I'll go through your list one at a time,

Surface Gravity: 1g

This one is likely a no, especially since you mean 1g everywhere except your mountaintops.
Being pedantic, The planet would have to be a perfect sphere to be exactly 1g thanks to gravity calculations.

Being more useful, those same calculations mean that, in order to average 1g across the majority of your planet, it has to be either mostly flat, or dip down in equal measures to have an increased (albeit small increase) gravity to match the decreased gravity from upward bulges.

Plus if you planet has day and night, that means that it has to be spinning (more details later). That spinning is going to do to your planet what it does to all of them, and make the equator line bulge a little bit.

That being said, you don't really need everywhere to be 1g, just the places people are living.

Once more point though, for a larger or smaller planet than Earth, you have to fiddle with the density of your planet. It'll be virtually impossible to have 1g without the same amount of mass, and with a larger planet, your density is lower, and vica versa. Both smaller and larger planets have some weird effects on gravity, and I encourage you to explore that.

Surface Air Pressure: 1 atmosphere

This is actually suffering from the same problems as Surface Gravity, mostly because of the intrinsic linkage between the two. With a higher gravity, you'll also have a higher air pressure because of the increased pull on particles pulling them down.

Air Composition: 78% Nitrogen, 21% Oxygen

This one isn't actually that bad, since it's almost exactly what Earth has already.
The only sticking point is that the last 1% is going to be a mess of everything else. Partially because of the cases of 'things exhale waste,' 'things can aerosolize,' and 'higher concentrations of things make the other two worse.'

That being said though, with only 1-2 billion people, you're not going to have a serious problem with pollution, especially with modern day techniques for cleaning the atmosphere.

Exact Days: 24 hours 365 days

This one's tough, because you'll have to balance two things perfectly, and have something to absorb all potential impacts.

Impact Absorption

This is going to take a full solar system to pull off, but here we go.
There will have to be some form of gas giants out past your planet. They act as a defensive shield for our Earth because they're effectively big gravity nets for anything passing through the system. Garbage bins if you will.
That's not all though, unless you've got a near Dyson sphere of gas giants, some things will get through, meaning that you'll have to have a more localized shield too- a large satellite of some sort (moons probably). They'll act as a physical barrier, but even then, some things might still get through to the planet itself. At that point, you just kinda have to hope that the atmosphere you've got is enough.

The whole reason that impact absorption matters is that each time your planet gets hit, you're going to have a slightly changed rotational period (admittedly, it would take hundreds-thousands before it starts to matter at all). But it does take some consideration.

Revolution

Now we've got revolution speed. This is going to be probably the most complicated because the gravitational force of the universe matters here.
Any time our planet gets closer to anything, it's going to have an effect on our orbit, and with anything but a perfectly circular orbit, we're either not going to have 365 days forever, or we're not going to have a perfect 24 hour day/night cycle. That means we'll have to keep the entirety of the solar system in a near perfect orbital cycle of maximum radius away from us (those gravity calculations earlier). That means a solar system of circular orbits, or accepting that we can't get everything perfect.

But that's not all, our rotation speed, and our moon/moons/satellites will affect our orbital periods too. That being said, that's all going on here on Earth, and our years are 365.2422 days

I don't want to deal with rotation, but just know that it doesn't change too much overall, that's just a (mostly) constant that drains over time because of entropy.
Plus its impact on orbital cycles is small, making about half go ever so slightly faster and the other half go exactly the same pace slower.

Seasons and Temperature

Seasons are easy, since they're based almost entirely on the tilt of the planet's axis. (complicates rotation and orbits more) you could probably even keep the Earth's tilt.

Temperature is a lot harder because that means you have to dive into Jet Stream currents as well as surface and deep level ocean currents. But since I don't know that much about those, It's probably safe to say that it's possible though not easy.

for ocean currents, we know that the colder water sinks (until a point, at which point it floats), which means that with the proper landmasses, you've got you're mild summers pretty easily. The mild winters at the same time could probably be managed through surface currents.
That all depends on your landmasses though and takes a lot more research.

Precipitation

This one isn't actually all that bad, you'll just need a lot of mountains and water. That being said, to prevent deserts on either side of the mountains, you'll have to have large bodies of water (probably oceans) close to both sides of the mountain.

No Windspeed Disasters

This one is a bit weird because there's two really good ways to solve it.
First would be even more mountains!
I know it sounds like I'm joking here, but due to what Tornadoes and Hurricanes need to really get going, the constant mountain boundaries would act as pretty solid deterrents against them. As evidenced by the topography of places with recurrent tornadoes.

Second would be even less temperature variance!
With less temperature variance, tornadoes and hurricanes would find the conditions for their creation less likely (still nonzero in either case) and they're less devastating in the event that they happen anyway (again, look at that map, just change it to look at temperature variance in the summer and winter).

Tectonic Activity

I'm going to be up front here. You cannot have tectonic activity and static continents. That is a mutually exclusive scenario.
Mountains are formed when tectonic plates push up against each other, and to do that, they have to be pulling away from somewhere else. Even in a simple scenario of just 2 plates, they have to move in opposing directions (toward each other) to make a mountain, while also making an oceanic rift.

The only way to have any activity like this would be to have the entire planet be a single tectonic plate, and that won't work due to convection currents in the magma below, in addition to the fact that it wouldn't meet the tectonic activity to prevent weathering problem.

Aquifer layers

I don't see why this would be a problem. You'll just need a higher amount of limestone than the Earth on your planet.

Stretch stuff

Seafood

If your coastal regions are mostly coral reefs and relatively shallow, (deep sea travel would be harder, but not impossible) you'll have plenty of habitat for sea critters.

Make sure that you include plenty of things like tide pools (for crabs, mussels, oysters) and deeper ocean (for large predators, whales, and large schools of fish)

Fertility

If you've got a bunch of mountain ranges, you're going to have some trouble with cultivating the land, but that's not what you're asking for. To have a guaranteed improvement of fertility, you'll need volcanic activity. Otherwise you'll be relying on people to do it, and people are dumb.

Mountain Views

You're in luck! Many of the things you've been asking for directly increase the number of mountains, and that means you've got plenty of mountain views to look at.

Good Beaches

You'll need a lot of ocean to do the weathering for decent sand (like white sand) as well as MANY fish, since a fair amount of the sand is "processed" by the fish and weathered down by ocean currents.

Side Note

There is one thing that I want to say: you'll have to find a plausible way to transport enough material to make the planet if you're planning on explaining how it came to be. The Earth is 5.972 × 10^24 kg according to google, and to put that in terms of a couple of things to put this in perspective:

it would take about 940 * 10^18 Elephants to make up the same amount of mass
19*10^18 Blue Whales
20*10^12 TOTAL HUMAN POPULATIONS OF EARTH

So it might be just as interesting to ask how the mass all got there (those were just the mass calculations for Earth by the way, not the solar system (the sun is 98% of the mass of the solar system))

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    $\begingroup$ note lots of mountains will actually increase the temprature gradient equator to pole, not reduce it, both due to increased shade at the poles and due to preventing efficient mixing of differentially heated air. $\endgroup$ – John Mar 26 at 13:48
  • $\begingroup$ I was hoping that the ocean currents would account for that, but they might not be enough on their own. Plus I had the idea of longitudinally aligned mountains, but that would have the same problem just in a different way $\endgroup$ – David Mar 26 at 13:54
  • $\begingroup$ Thanks for your lengthy answer. I know the tectonic part is not easy to vision, but I think there might be a way to say place a continental plate around a great number of oceanic plate, and set the density of the plates artfully, and make the density variation fo the continental plate varies precisely in accordance with the surface feature, e.g. valley for high density, mountain for low density, such that it behaves in a highly regulated way when squeezed from all around, making the border jagged in a certain may self-align the plates so they don't plastically deform. $\endgroup$ – Meatball Princess Mar 26 at 14:12
  • $\begingroup$ I'll admit that I'm not a geologist, or trained in such matters so I definitely could have overlooked something. Hopefully you'll find some way to address that part $\endgroup$ – David Mar 26 at 14:20
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    $\begingroup$ @MeatballPrincess tectonic plates equals earthquakes and volcanoes there is no way around it, oceanic plates and continental plates both produce them. Plates plastically deform because they are massive and under tremendous force, anything will bend under those kinds of forces. plus when plates do not plastically deform thats what causes earthquakes. $\endgroup$ – John Mar 26 at 20:41
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Build an artificial planet, a giant artificial space habitat, out of materials from asteroids and other space objects.

The planet will be inside out compared to a natural planet, being a very long hollow cylinder that spins to create simulated gravity.

The outside or bottom layers should have thick walls or floors to adsorb meteor impacts and layers of water tanks to adsorb radiation. Above them should be many floors of a giant building that wraps around the entire cylinder, containing the homes and work places of the inhabitants. Above, on the roof of the giant world building there will be a simulated natural habitat for human recreation, looking like an attractive Earthly landscape.

Where will the farms be on the surface landscape? Nowhere. Food will be grown inside the world building in hydroponic and aeroponic facilities requiring far fewer square feet per person fed than dirt farms. Or possibly food will be produced by food synthesizing machines.

The diameter of the world would be about 10 to 100 miles, giving it a circumference of 31.4159 to 314.159 miles, and the length of the cylinder could be 10 to 10,000 miles, giving it a surface area of 314.159 to 3,141,590 square miles, multiplied by the number of complete levels of floors it might have. Since the planet Earth has a surface area of about 196,900,000 square miles, if the cylindrical space habitat has a surface area on one floor of 314.159 to 3,141,590 square miles, it would need to have 62.675269 to 626,752.69 complete floors to have the same surface area as the Earth, but would need only a fraction of the area of the Earth to support only one or two billion people.

This is more or less a vastly scaled up version of a typical design for an artificial space habitat designed for maybe 10,000 people.

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