How do you create a habitable planet that is scientifically feasible? There are a number of characteristics that determine what makes a planet habitable for life, but change those characteristics, and the chances of life will change dramatically. So, how do you get it right? This guide will show you how to ideally create your habitable planet.
Your Star (Or Stars)
Before you place your habitable planet, you need a star. This is where most of your heat will originate from, but it isn’t as simple as just placing one down. There are various options to choose from.
Number of Stars
The first thing to know about your options is that not every star system will have just one star. In fact, around 60% of star systems have two. Usually, one of the stars is more ma*sive than the other, but this isn’t always the case. It is also possible to have more than two stars, but so far, astronomers haven’t found very many exoplanets (planets beyond the Sun) in systems with more than three, so ideally, you should choose between one, two, or three stars.
If you choose to have more than one star, you can decide on how you want to structure your system. You can place the two stars close together and have your planets orbit beyond them, or you can place the stars far apart and have the planets orbit one of the two stars (and you can also add in more planets to the other as well).
If you choose to have your stars close together, you will want to place your planets at least four times the distance as the average separation between your two stars. If your planets are placed too close to the binary pair, their orbits will become unstable. If you do this right, your planet will have the double sunrise and sunset, much like Tatooine from Star Wars.
If you choose to have your stars far apart, make sure your planet is close enough to the star you intend for it to orbit, or the planet’s orbit will likewise become unstable because of gravity from the other star interacting with your planet.
Also, if you have more than two stars, be very careful. Place the third star incorrectly, and your entire star system will become unstable. It is easiest to have the third star orbit the other two, or in other words, having a single star orbit binary stars (a pair of stars, in simpler terms).
All of this means that your habitable zone needs to fall close enough or far enough from your star or stars. For stars placed distantly, the star your habitable planet does not orbit will have little effect on your planet’s climate, but if your stars are close together, they will share responsibility in maintaining your planet’s climate. Keep this in mind when deciding where you want your planet to orbit its parent stars.
Types of Stars
Of course, there isn’t just one single type of star, but rather they come in many different flavors. Astronomers cla*sify them in terms of temperature and luminosity.
In terms of temperature, stars are cla*sified into the OBAFGKM cla*sification system. O-type stars are hotter than B-type, B-types are hotter than A-types, and so on. O, B, and A, types will have a bluish tint to their color, and the hotter they are, the bluer they will appear. F and G-type stars appear white, but G-types will have a yellowish tint. K-type stars are yellow, and M-type stars are orange.
Now as for luminosity, you’ll want a main-sequence star. This type of star is in the stable hydrogen-burning phase of its lifecycle. If the star gets too old, it will expand, and they become unstable, meaning your habitable zone will move periodically, which is bad news for a habitable planet. Also, if the star expands far enough, it could actually consume your habitable planet, and that spells disaster for any life on said planet, so choose a main-sequence star.
It is my a*sumption that you want a planet with complex, multicellular lifeforms. For this to occur, the star needs to stay in the main-sequence for at least 3.5-4 billion years, and even longer if you want an extraterrestrial civilization to emerge. Set your star’s age to around this amount to make multicellular life on your planet plausible.
Of course, your star needs to be able to last long enough for this to happen. How long a star lasts is determined by its ma*s. The more ma*sive a star is, the shorter it will live. Also, the more ma*sive a star is, the hotter it will be, so this will limit which type of stars you can use. Because of this, stars that are more ma*sive than the cooler F-types won’t be suitable for complex life.
Also, it is unlikely for M-type stars to host habitable planets. Their planets have to be very close to their parent star in order to be in the habitable zone, and this means that they will likely be tidally-locked, meaning there is one side of the planet being blasted by the star’s heat all the time, but the night side is forever without the star’s heat, so it will be frozen. This will limit life to the area where night and day meet. Even worse, M-type stars tend to be very active, meaning they constantly erupt, sending flares that their planets will have to face. We will discuss this in greater detail when we discuss your planet’s magnetosphere.
So, ideally, you want to choose a K, G, or F-type main-sequence star.
So, now that you have your star(s) placed down, you can now place your habitable planet. Simply place a random planet (or a blank planet if you’re interested in using Universe Sandbox’s planetscaping feature) in your habitable zone (you can show habitable zones in the view options).
Ma*s of Your Planet
With your planet placed down, you’ll have to edit some of its parameters. Let’s start with ma*s.
Your planet should have a ma*s comparable to Earth’s. If it isn’t ma*sive enough, it won’t be able to retain water or even an atmosphere. If it is too ma*sive, the gravity will be too high, and it might actually be more plausible for it to have become a gas giant during formation.
So choose a ma*s between say 0.8 and 3 times the ma*s of Earth, and you’ll be set to go.
Composition of Your Planet
Next, you’ll want to tweak your planet’s composition. Specifically, you will want to have your planet be composed of at least 18% iron. This will be important for your planet’s magnetosphere.
Your Planet’s Magnetosphere
Earth’s magnetosphere is generated by a combination of its rotation and the ma*s of it’s iron core. This is why you want some iron in your planet’s composition. The more ma*sive it is, the stronger your magnetosphere will be, and the faster your planet spins, your magnetosphere will likewise be stronger.
But keep in mind that your planet’s rotation will have a serious impact on your planet’s weather, so don’t set your rotational period to anything crazy.
With that aside, what does the magnetosphere do?
The thing is that stars emit a steady stream of particles called the solar wind. This stream s*rips away any atmosphere (not immediately, but over time), and also any water as well. Both of these will make life on your planet difficult if not impossible. A magnetosphere serves as a defense against the solar wind by deflecting it, sort of like a shield.
It will also provide some protection against radiation emitted by your star, and this is why flares from those red dwarves will pose a complication for life, because they produce radiation, and because planets here are tidally-locked, a habitable one will likely have a rotational period too slow for a strong magnetosphere, so it won’t be strong enough to deflect the radiation.
Your Planet’s Atmosphere
A planet’s atmosphere is important for life. An ozone layer on Earth protects the planet from harmful ultraviolet light, and oxygen supplies life with a means of facilitating biochemical reactions. Carbon dioxide provides the planet with a greenhouse effect, keeping it warm, and also supplies plants with a means of producing sugars that they will use to store energy. Also, having an atmosphere allows for weather events which will deliver rain to regions of the planet not adjacent to a body of water. So an atmosphere does quite a lot for life on your planet, and you will need the right one to make your planet scientifically feasible.
The atmospheric pressure on your planet may not seem too important, but it affects the temperature at which water (and other substances) melts or boils, and you want water to be in the liquid state. So set a pressure to something similar to Earth’s. (1 atm is about the pressure of Earth’s atmosphere).
As of the time this guide was created, Universe Sandbox does not feature atmospheric composition, so we will not discuss it here. It will affect your atmosphere’s color, and I plan on detailing that in a separate guide.
Although atmospheric composition is not featured, the greenhouse effect is. You can set the level of the greenhouse effect and the infrared emissivity. The latter describes how much infrared light your planet will emit (it does that to get rid of heat). The infrared light will then be distributed by greenhouse gases, so the higher the infrared emissivity, the higher the greenhouse effect. Also, because planets emit infrared to reduce temperature, it will do so more at higher temperatures, so the higher the temperature, the higher the greenhouse effect.
Lastly, higher levels you set on the greenhouse effect, the more heat it will contribute to your planet.
Your Planet’s Climate
As of the time at which this guide is created, precipitation and weather is not simulated in Universe Sandbox, but the temperature is, so we will discuss how it works.
Albedo represents the amount of heat it reflects back into space. The value range spans from 0 to 1. So, for example, if you set it to 1, your planet will reflect all heat it receives from its host star, whereas if it is set to 0, then it will absorb all of it.
Ice and snow reflect the most energy. They reflect nearly all of it, for that matter. Clouds also have a high albedo, but not as much as ice or snow. Ocean has the lowest albedo, and land varies depending on what the surface is like. In general, lighter-colored materials will have higher albedo values, and for reference, Earth’s albedo is about 0.3.
Now, what temperature is considered ideal? What’s obvious is that you want it between 0 and 100 degrees Celsius (or between 32 and 212 degrees Fahrenheit), but that’s a pretty wide range.
If you want your planet to be habitable for Earth-like organisms, the best temperature is between 12 and 18 degrees Celsius.
What about Exotic Planets?
Now, in theory, it is possible for a lifeform to use something other than water in a similar manner as those on Earth do, but it’s sketchy.
Different substances will have different melting and boiling points, which means that the ideal temperature range will change. Keep this in mind if you want these kinds of planets.
This is all we can share for Creating Your Scientifically Feasible Habitable World – Universe Sandbox for today. I hope you enjoy the guide! If you have anything to add to this guide or we forget something please let us know via comment! We check each comment! Don’t forget to check SteamClue.com for MORE!
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