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How Can a Planet Be Made Habitable?



Nature has done a pretty good job of making the Earth a habitable place. If it hadn’t, you wouldn’t be reading this right now. Or perhaps you would be, but you wouldn’t be a human and you wouldn’t be on Earth. The point is, we know what it takes to make a planet habitable simple because we’re living somewhere habitable. So, if we wanted to recreate the process elsewhere, what would it take? Here’s how you make a planet habitable:



1. Make sure it’s not too close to its sun - but not too far away either.
When astronomers study distant suns and their planets, they define a region as a “habitable zone” based on the sun’s size and how much energy it puts out. If a planet falls within that zone, it’s potentially habitable. Since we currently don’t have the capability of moving a planet from one orbit in its solar system to another, we have to find planets that are already in habitable zones. Fortunately for us, several candidates have already been found.

2. Give it an atmosphere.
Habitable generally means comfortable in the sense that if you need to wear a spacesuit 24/7 to survive, it probably doesn’t qualify. Humans need oxygen to breathe, so an atmosphere that has oxygen and plenty of it (not too much, of course) is needed. Of course, the planet needs to be capable of retaining that atmosphere, so strong gravity and/or a magnetic field are important components. And unless we could trigger natural processes to create an atmosphere, we would have to generate one artificially, which we currently don’t have the technology to do on a massive scale.



3. Make sure there’s water.
Why does NASA always look for water in the search for life outside Earth? Simply put, water is the basis for life. To survive, and to have a temperate climate, you need water. We would either need to bring in massive quantities of water, or the planet should already have it either in ice or liquid form. There are plenty of “water worlds” out there in their star’s habitable zone, so it’s not out of the question to think we could find something that suits our needs, should it ever come to that.
 
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Not to many water worlds in the right spot with a big moon.
Lots of water worlds that are a big moon of a biggish planet in the right place.

We might be an oddball,
We might be looking in the wrong place for life of anything other than very basic life as the earth size worlds we find are wobble beast like earth would be without a big moon.
Unstable climate worlds.

My guess is ET wakes up to see a big planet in the sky and when they search for other ET's they look for moons of planets in the right place..
 
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Not to many water worlds in the right spot with a big moon.
Lots of water worlds that are a big moon of a biggish planet in the right place.
We might be looking in the wrong place for life of anything other than very basic life as the earth size worlds we find are wobble beast like earth would be without a big moon.
Although it is believed that our Moon stabilizes the tilt of the axis of the Earth, it is just as likely that a planet this size with no moon, or a smaller moon, might not undergo significant precession of the axial tilt.
 

rod

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This is an interesting 3 point outline on making a habitable Earth. Without the Moon, what happens to ocean tides and water over long periods of time, without tides? Wrong lunar mass (too large) in orbit around the Earth, we could be more volcanic like Io at Jupiter. There are many variables required to explain how the Earth is habitable, three touches only on a small number but it is a good start. We have the Earth's orbital eccentricity to consider. This site shows 4173 confirmed exoplanets, The Extrasolar Planets Encyclopaedia I ran a MS SQL query and found the average value for e = 0.17. There are many, highly eccentric orbiting exoplanets at their host stars that are confirmed today. Wild swings in Earth's eccentricity, and folks will really be talking about the weather and climate change :) The Earth's rotation rate could be an issue. Spin to fast and what happens to winds at the surface from atmospheric circulation? We have the spin rate of the Sun too. Presently the Sun spins at its equator near 2 km/s however, T Tauri stars, various red dwarfs, can spin 10-20 km/s so flare greatly along with many corona mass ejections. How about enjoying some really large, solar flares while soaking up the sunshine on a beach this coming summer? Using Wien's law, a star with 1E+4 Kelvin temperature (spectral class A star) peaks near 290 nm wavelength, very energetic UV light emitted. The list could go on here like explaining the origin of the Moon from a cosmic collision (giant impact model) that likely resulted in the synestia phase of matter for the early Earth-Moon. No water in the synestia phase of matter (the new computer simulations of a giant impact event). Somehow, the Big Bang event using gas, random collisions of various particles and sizes, made the Earth habitable today :)
 
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I strongly suspect that an existing non-terrestrial biology will not make a planet more suitable for Humans - extraordinarily interesting and of unprecedented value scientifically - but will probably make it extremely dangerous and less suitable for humans. Biology, even if essentially the same kind of biochemistry - can make more kinds of dangerous toxins and allergins than exist without life. Expecting biological compatibility between terrestrial and non-terrestrial biology seems extremely optimistic.

When astronomers talk about about "habitable" worlds my understanding is they are not talking about targets for colonisation, but targets for finding non-terrestrial life.

A planet with a Nitrogen and Oxygen dominated atmosphere would be almost certainly be that way because of life - finding it only to treat is as real estate, then contaminate it and supplant native life with terrestrial life seems wasteful of the scientific value. And for anyone capable of reaching it from here, unnecessary to their survival.

Interstellar colonisation of planets makes fun fiction but a poor ambition - and if any missions become possible it will take capabilities that mean not being dependent on planets to survive when they get there.
 
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Although it is believed that our Moon stabilizes the tilt of the axis of the Earth, it is just as likely that a planet this size with no moon, or a smaller moon, might not undergo significant precession of the axial tilt.
I agree no guarantee that worlds we find will have wobbles.
I think most will without a decent moon so 90-95% will wobble.
Not a big deal for the water part of a water world but a big problem for things living on land.
Even tiny wobbles on earth with it's moon get us into ice ages and severe climate changes.
We could expect only a very few moonless earths to be stable places as stable as earth.
 
This is an interesting 3 point outline on making a habitable Earth. Without the Moon, what happens to ocean tides and water over long periods of time, without tides? Wrong lunar mass (too large) in orbit around the Earth, we could be more volcanic like Io at Jupiter. There are many variables required to explain how the Earth is habitable, three touches only on a small number but it is a good start. We have the Earth's orbital eccentricity to consider. This site shows 4173 confirmed exoplanets, The Extrasolar Planets Encyclopaedia I ran a MS SQL query and found the average value for e = 0.17. There are many, highly eccentric orbiting exoplanets at their host stars that are confirmed today. Wild swings in Earth's eccentricity, and folks will really be talking about the weather and climate change :) The Earth's rotation rate could be an issue. Spin to fast and what happens to winds at the surface from atmospheric circulation? We have the spin rate of the Sun too. Presently the Sun spins at its equator near 2 km/s however, T Tauri stars, various red dwarfs, can spin 10-20 km/s so flare greatly along with many corona mass ejections. How about enjoying some really large, solar flares while soaking up the sunshine on a beach this coming summer? Using Wien's law, a star with 1E+4 Kelvin temperature (spectral class A star) peaks near 290 nm wavelength, very energetic UV light emitted. The list could go on here like explaining the origin of the Moon from a cosmic collision (giant impact model) that likely resulted in the synestia phase of matter for the early Earth-Moon. No water in the synestia phase of matter (the new computer simulations of a giant impact event). Somehow, the Big Bang event using gas, random collisions of various particles and sizes, made the Earth habitable today :)
I agree i think we strongly underestimate the importance of a moon being just the right size for stable land life and stable planet itself.

Without tides a planet could easily become a stagnant low oxygen water world.
Or spin so fast that climate is crazy.
 
I strongly suspect that an existing non-terrestrial biology will not make a planet more suitable for Humans - extraordinarily interesting and of unprecedented value scientifically - but will probably make it extremely dangerous and less suitable for humans. Biology, even if essentially the same kind of biochemistry - can make more kinds of dangerous toxins and allergins than exist without life. Expecting biological compatibility between terrestrial and non-terrestrial biology seems extremely optimistic.

When astronomers talk about about "habitable" worlds my understanding is they are not talking about targets for colonisation, but targets for finding non-terrestrial life.

A planet with a Nitrogen and Oxygen dominated atmosphere would be almost certainly be that way because of life - finding it only to treat is as real estate, then contaminate it and supplant native life with terrestrial life seems both wasteful of the scientific value.

Interstellar colonisation of planets makes fun fiction but a poor ambition - and if any missions become possible it will take capabilities that mean not being dependent on planets to survive when they get there.
Yep don't eat the native fruits and vegetables.
Sure to be toxic to humans.

Even visiting you probably won't be allowed to go home.
 
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I agree no guarantee that worlds we find will have wobbles.
I think most will without a decent moon so 90-95% will wobble.
 

rod

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FYI, there are many reports on the NASA ADS system astrophysics data system that involve simulating the Earth without the Moon and axis and tilt as well as exoplanet studies, with or without moons. In an accretion disk, the Earth can form with a very slow rotation period and the south pole facing the Sun in its orbit or the north pole. The giant impacts in the computer models, yield many interesting differences compared to what we do see today in the Earth-Moon system.
 
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It seems reasonable, that since a planet forms from a rotating disc of debris, that the rotation of the planet that forms will be stable and without wobble unless disturbed. It also seems reasonable that asteroids and other debris the may be attracted to the mass of the newly formed planet will not affect the spin. It is further reasonable that an impact by a large enough planetoid could instill a wobble into the rotation of the planet. Even a planetoid that does not impact the planet, but is instead captured and becomes a moon could possibly instill a wobble into the rotation of the planet.
Therefore, it is possible that all planets start out with very stable rotation with no wobble and are therefore not rare.
 
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Yep don't eat the native fruits and vegetables.
Sure to be toxic to humans.

Even visiting you probably won't be allowed to go home.
I was thinking any exposure would be potentially dangerous - breathing the air (with all the airbourne microorganisms and products of life) would be enough, let alone eating, drinking or touching anything.
 
Both Venus and Mars wobble and Earth with a moon small wobble.
Shows that most if not all planets we find will wobble.

ET has a very long list of needs and luck to exist.
Land%
Planet size
Moon size?
Water%
Asteroid%
Planet stability
Sun stability
Neighbor planets activity
Nearness to a super nova.
Luck not to get stuck in dinosaur planet that persists.

Finding life i think most worlds in the right spot will have.
Finding ET on land might be a very long search.
 
I was thinking any exposure would be potentially dangerous - breathing the air (with all the airbourne microorganisms and products of life) would be enough, let alone eating, drinking or touching anything.
Oh i agree going and landing on a planet without a few 100 years of study first won't happen.
Anyone doing so would have a X placed on them :)
 

rod

Oct 22, 2019
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FYI, some of the comments here are very interesting. Much study is underway concerning exoplanet spins and axis tilts because of weather and climate, for life. Currently we have 4176 exoplanets confirmed, The Extrasolar Planets Encyclopaedia How many of these are well measured concerning their spin rates, axis tilts and weather conditions? I ran a MS SQL query against the list for exoplanets with masses <=3 earth masses. 54 exoplanets reported for duty with average mass 1.57 earths. Average orbital period 10.18 days. Do we have solid measurements supporting the axis tilt and spin rates as well as weather and climate on these 54, for example do some have 24 hour days like earth and seasons? I do see research reports indicating that secular spin-axis and spins is a serious issue for life studies on exoplanets. "4. Conclusion The spin-axis dynamics of a planet plays a major role in its climate setting, and, by extension, in its suitability for life. However, the rotation properties of exoplanets are still very poorly constrained…", Secular spin-axis dynamics of exoplanets
Read the Abstract and entire PDF report available, a number of free parameters are in use in the computer models in efforts to show what a good, axis and spin is for an exoplanet that could be habitable. Other studies show much chaos in planet formation, especially for rocky planets in the final stages of accretion. "Giant impacts dominate the final stages of terrestrial planet formation and set the configuration and compositions of the final system of planets.", The Energy Budgets of Giant Impacts

The idea that planets accrete from large dust disks and just grow into a nice, stable exoplanet that is suitable for life has issues in modeling as well as verifying rotation rates, axis tilts, and weather and climate on exoplanets. Remember a number of *free parameters* are used in the computer models too. The giant impact model for the origin of our Moon does not feature a rapid spinning proto-earth before the impact (very slow if any rotation) but a much faster rotating proto-earth after the impact and slow accretion growth to present mass and size after the impact. "In the new model, a high energy collision left a mass of vaporized and molten material from which the Earth and Moon formed. The Earth was set spinning with a two-hour day, its axis pointing towards the Sun.", New theory explains how the moon got there

For Rod, I think more caution is needed when presenting a simple solution to making a good, habitable Earth :)
 
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Both Venus and Mars wobble and Earth with a moon small wobble.Shows that most if not all planets we find will wobble.
No, it does not. It only shows that several planets here do. That may only be a feature of a solar system with a gas giant inside the orbit of a huge asteroid belt, repeatedly coaxing large rocks out from that asteroid belt and throwing them at the inner planets. The large impact craters on the inner planets, that were created very late in the life of those planets, would support that.

Three planets out of probably a centillion planets is not a representative sample.
 
No, it does not. It only shows that several planets here do. That may only be a feature of a solar system with a gas giant inside the orbit of a huge asteroid belt, repeatedly coaxing large rocks out from that asteroid belt and throwing them at the inner planets. The large impact craters on the inner planets, that were created very late in the life of those planets, would support that.

Three planets out of probably a centillion planets is not a representative sample.
We can only guess at what we see happening here.
No reason to believe that any other rocky planet wont wobble.
All do here so probably most do.

Could be just our system setup but could be just a reality of most rocky planets.
 
FYI, some of the comments here are very interesting. Much study is underway concerning exoplanet spins and axis tilts because of weather and climate, for life. Currently we have 4176 exoplanets confirmed, The Extrasolar Planets Encyclopaedia How many of these are well measured concerning their spin rates, axis tilts and weather conditions? I ran a MS SQL query against the list for exoplanets with masses <=3 earth masses. 54 exoplanets reported for duty with average mass 1.57 earths. Average orbital period 10.18 days. Do we have solid measurements supporting the axis tilt and spin rates as well as weather and climate on these 54, for example do some have 24 hour days like earth and seasons? I do see research reports indicating that secular spin-axis and spins is a serious issue for life studies on exoplanets. "4. Conclusion The spin-axis dynamics of a planet plays a major role in its climate setting, and, by extension, in its suitability for life. However, the rotation properties of exoplanets are still very poorly constrained…", Secular spin-axis dynamics of exoplanets
Read the Abstract and entire PDF report available, a number of free parameters are in use in the computer models in efforts to show what a good, axis and spin is for an exoplanet that could be habitable. Other studies show much chaos in planet formation, especially for rocky planets in the final stages of accretion. "Giant impacts dominate the final stages of terrestrial planet formation and set the configuration and compositions of the final system of planets.", The Energy Budgets of Giant Impacts

The idea that planets accrete from large dust disks and just grow into a nice, stable exoplanet that is suitable for life has issues in modeling as well as verifying rotation rates, axis tilts, and weather and climate on exoplanets. Remember a number of *free parameters* are used in the computer models too. The giant impact model for the origin of our Moon does not feature a rapid spinning proto-earth before the impact (very slow if any rotation) but a much faster rotating proto-earth after the impact and slow accretion growth to present mass and size after the impact. "In the new model, a high energy collision left a mass of vaporized and molten material from which the Earth and Moon formed. The Earth was set spinning with a two-hour day, its axis pointing towards the Sun.", New theory explains how the moon got there

For Rod, I think more caution is needed when presenting a simple solution to making a good, habitable Earth :)
How easy for earth to be a non habitable planet if it spun at 45 tilt or on it's side.
I think moonless earths are going to have long periods of time when they do and alter that spin axis abruptly.
Not good for things crawling out onto land and trying to adapt.
And pretty easy to see runaway ice world or desert scenarios even on small tilt changes.

We might find moonless earth size planets with life but i think basic life is what we will find on them.

ET IMO will have a wonderful view of a Neptune size world in the sky and a few other moons also.
 
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No reason to believe that any other rocky planet wont wobble.
Why? It is reasonable that a massive body that is formed spinning without any wobble will continue to do so unless acted upon by an significant outside force. Without an outside force, what would cause it to begin wobbling.
All do here so probably most do.
How do you figure that three planets out of the number possible could be a representative sample?
 
Why? It is reasonable that a massive body that is formed spinning without any wobble will continue to do so unless acted upon by an significant outside force. Without an outside force, what would cause it to begin wobbling.

How do you figure that three planets out of the number possible could be a representative sample?
Water.
Nature of habitable planets that have water will wobble.
Any gravitational force from any other planet in the system will induce a wobble.

To some extent even without water planets will wobble with uneven crust movement.

Other than a big moon to stop erratic changes or being a big moon I'm not to sure how you set an individual planet that has water into a stable place for life other than basic life adaptable to extreme change.

An all water world probably won't be effected to much from tilt change unless it ends up spinning pole faced for a long time,


JMO
 

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