[Moontanman]

Does anyone know of a site I can go to that would help me figure out how many eath sized planets could orbit around a sun like star in close enough to sustain life? I know that in theory our sun could have three but only has one. Could there be five say starting with the asteriods and stoping at venus?How close could earth sized planets be in stable orbits around the sun in any orbit as close or closer than the asteriods? I am writing and I need a little bit of help since I am deficent in the math department.

Michael

[Boerseun]

There are many variables, too many, in fact, to give you a straight-up answer. For instance, how thick is the planet's atmosphere, and what does it consist of? Like Venus, which is almost identical in size and composition to Earth, but is entrenched in a permanent, fatal greenhouse-effect due to the composition (and volume) of its atmosphere.

It seems as if its proximity to the sun isn't as important to the hellish heat felt at the surface as is the thick atmosphere. Even if Venus was at Earth's orbit, it would've been a hell-hole.

Mars, again, sometimes reaches balmy temperatures in the mid twenties (Celcius). The nights aren't as pleasant, though, and the main reason for this, once again, is Mars' atmospheric composition (and lack of volume). If there was more carbon and water vapour in the Martian atmosphere, it could have been able to retain more heat at night. So - as far as I'm concerned, the habitable region for our solar system extends from closer than the Venutian orbit to further than the Martian orbit. The deal-breaker, of course, being the atmospheric composition of the specific planet in question.

[Moontanman]

Originally Posted by Boerseun

There are many variables, too many, in fact, to give you a straight-up answer. For instance, how thick is the planet's atmosphere, and what does it consist of? Like Venus, which is almost identical in size and composition to Earth, but is entrenched in a permanent, fatal greenhouse-effect due to the composition (and volume) of its atmosphere.

It seems as if its proximity to the sun isn't as important to the hellish heat felt at the surface as is the thick atmosphere. Even if Venus was at Earth's orbit, it would've been a hell-hole.

Mars, again, sometimes reaches balmy temperatures in the mid twenties (Celcius). The nights aren't as pleasant, though, and the main reason for this, once again, is Mars' atmospheric composition (and lack of volume). If there was more carbon and water vapour in the Martian atmosphere, it could have been able to retain more heat at night. So - as far as I'm concerned, the habitable region for our solar system extends from closer than the Venutian orbit to further than the Martian orbit. The deal-breaker, of course, being the atmospheric composition of the specific planet in question.

I asked too many questions, I meant to only ask one. I realalise that habitibility depends on much other than orbit what i really wanted was how many earth sized planets could orbit stabely from the asteroids or a bit further out to with in the orbit of venus. Anything else is too what if. I have been debating this with my self as i write many times and I can vary the parameters of the atmoshere but it's difficult to just up and say I want ten planets to be orbiting in this area when only three will orbit there with any stability. I am also writing about a mega-jupiter sized planet, not big enough to be a brown dwarf but bigger than jupiter and how many earth sized moons can it have? that would be a great way to get several habital planets into orbit around one star but how big would teh planet have to be to have say seven earth sized moons? hard to say really with out math that is very much far beyond me, maybe not possible at all. but leaving out the earth like part and leave in earth sized how many planets could orbit around our sun in the inner solar system?

michael

[PuGZ]

Sustain what kind of life? Regular human life and mesophiles? Or any life at all? You might be absolutely amazed at some of the conditions that extremeophiles live in -- it will also open up your options considerably.

That said, I have no idea how to go about answering your question. Just wanted to give you an idea of some of the conditions that life can live in!

[CraigD]

Originally Posted by Moontanman

Does anyone know of a site I can go to that would help me figure out how many eath sized planets could orbit around a sun like star in close enough to sustain life?

This PNAS article gives a an overview of the question of the stability of solar system in general. There are many others. Searching for “stability orbit” produces a long list. I recall some good treatments in popular science magazines such as Scientific American, and in books such as James Glick’s “Chaos”.

Originally Posted by Moontanman

how many earth sized planets could orbit stabely from the asteroids or a bit further out to with in the orbit of venus.

A survey of the literature on the subject, or writing and running your own long-duration gravitational simulations, reveals this to be a difficult problem, and suggest that “stable” is only a relative term. Fairly convincing simulations suggest that, over very long time frames (billions of years), very few orbital systems are stable. One of the great challenges of orbital simulations modeling the solar system is, in fact, getting the model to match observed data – most of them have the solar system ejecting the inner planets, while the giants spiral into increasingly tight orbits, resembling many of the extra-solar systems that have been measured.

Papers such as the PNAS article above note that orbital resonance – that adjacent orbiting bodies complete small, nearly whole numbers of revolutions in the same time period (eg: 1:2, 2:3, 3:5) - is an important factor in determining stability. Although resonance is found strongly in the moon systems of Jupiter and other giant planets, and weakly in inner and outer planets, this doesn’t appear to be the dominant factor in an explanation why the solar system is so stable (quick reference to planetary orbit data: Table of planets and dwarf planets in the Solar System - Wikipedia, the free encyclopedia).

Key to the whole solar system’s stability – including the inner planets - seems to be the preservation of the orbits of the giant planets. Key to this appear to be their acquisition of kinetic energy from gravitational interaction with small, irregular-orbit bodies (comets and other Kuiper belt objects). These many bodies seem to function somewhat like a storage battery to “keep the giant planets running” by their occasional “sacrifice”. However, since interactions between the giant planets and these stray bodies appears, to a simple analysis, to be as likely to take kinetic energy from the larger body as give it, mystery remains.

From my read and work on the question, I’ve come to consider the long-term stability of orbital systems like the solar system a hard problem. Unfortunately, it doesn’t seem one amenable to simple, elegant theories, but one that requires a lot of intense number crunching and ad-hock explanations.

Originally Posted by Moontanman

I know that in theory our sun could have three but only has one.

I can’t recall such a theory, but imagine, based on the complicated but apparently stable interactions of giant planet moons, that there could be many planets in circular orbits close to Earth’s, at Lagrangian points, “shepherding” or otherwise complicatedly interacting with one another. Theories such as the giant impact hypothesis for the formation of the Moon suggest that the inner solar system may have once been like this, but that such arrangements aren’t stable, evolving over time into what we observe now.

All-in-all, this is a big, messy problem, likely IMHO to require lifetimes of work and lots of computing power to answer with confidence.

[Moontanman]

Originally Posted by CraigD

This PNAS article gives a an overview of the question of the stability of solar system in general. There are many others. Searching for “stability orbit” produces a long list. I recall some good treatments in popular science magazines such as Scientific American, and in books such as James Glick’s “Chaos”.A survey of the literature on the subject, or writing and running your own long-duration gravitational simulations, reveals this to be a difficult problem, and suggest that “stable” is only a relative term. Fairly convincing simulations suggest that, over very long time frames (billions of years), very few orbital systems are stable. One of the great challenges of orbital simulations modeling the solar system is, in fact, getting the model to match observed data – most of them have the solar system ejecting the inner planets, while the giants spiral into increasingly tight orbits, resembling many of the extra-solar systems that have been measured.

Papers such as the PNAS article above note that orbital resonance – that adjacent orbiting bodies complete small, nearly whole numbers of revolutions in the same time period (eg: 1:2, 2:3, 3:5) - is an important factor in determining stability. Although resonance is found strongly in the moon systems of Jupiter and other giant planets, and weakly in inner and outer planets, this doesn’t appear to be the dominant factor in an explanation why the solar system is so stable (quick reference to planetary orbit data: Table of planets and dwarf planets in the Solar System - Wikipedia, the free encyclopedia).

Key to the whole solar system’s stability – including the inner planets - seems to be the preservation of the orbits of the giant planets. Key to this appear to be their acquisition of kinetic energy from gravitational interaction with small, irregular-orbit bodies (comets and other Kuiper belt objects). These many bodies seem to function somewhat like a storage battery to “keep the giant planets running” by their occasional “sacrifice”. However, since interactions between the giant planets and these stray bodies appears, to a simple analysis, to be as likely to take kinetic energy from the larger body as give it, mystery remains.

From my read and work on the question, I’ve come to consider the long-term stability of orbital systems like the solar system a hard problem. Unfortunately, it doesn’t seem one amenable to simple, elegant theories, but one that requires a lot of intense number crunching and ad-hock explanations.I can’t recall such a theory, but imagine, based on the complicated but apparently stable interactions of giant planet moons, that there could be many planets in circular orbits close to Earth’s, at Lagrangian points, “shepherding” or otherwise complicatedly interacting with one another. Theories such as the giant impact hypothesis for the formation of the Moon suggest that the inner solar system may have once been like this, but that such arrangements aren’t stable, evolving over time into what we observe now.

All-in-all, this is a big, messy problem, likely IMHO to require lifetimes of work and lots of computing power to answer with confidence.

Obviously I've asked a question far more complicated than I thought. I do understand the difference between micro and macro life. Micro life could exist somewhere on almost all of the planets, macro life can possibly exist on only two or three and for sure on only one. The Earth of course has macro life (multi cellular) but there is some idea that some of the moons of the outer solar system might have oceans under their surface that "might" have life and maybe even macro life (it's not completely clear if the energy requirements for macro life exists there) I guess my question couldn't really be simple enough to have an easy answer. I obstificated it by not asking it correctly to begin with. All I really wanted to know was how many earth sized planets could orbit in the inner solar system. I add that the asteroid belt should be the starting place but I confused it by stating that inside the orbit of Venus should be the end point inside the solar system. If you can manipulate the atmosphere of a planet you could expand the life zone quite a bit from the .95 and 1.15 au that is commonly stated as the limit for the sun. (close but maybe not exact figures) With a dense atmosphere or less dense depending on where you are a planet could harbor life quite a bit further away than 1.15 AU and maybe a little closer than .95 AU. I was just wondering how many planets you could conceivably have to play around with under the best circumstances. Probably a large gas giant with earth sized moons would be the best way to have several planets with life but of course we don't know how many earth sized moons a gas giant could have. I hope I have at least cleared up my question even if the answer is far more complex than I imagined.

Michael

[Moontanman]

I can also see by some of the links provided that there probably isn't a real anser to my question other than things change, sometimes they change fast sometimes slowly and not always predictably. Planetary orbits flollow this premise rather closely if I understand what i am reading. Want to try another one? How long would it take a Neptune or Uranus sized planet to cool down until it had a solide ice surface? I guess I am assuming that these planets have a deep planetary ocean of many thousands of miles in depth. if uranus was to cool down until it has solid ice surface and a "thin" (compaered to jupiter) atmosphere of hydrogen and methane how far into the future would we have to wait and how much would the sun slow down this procedure? I have lots of questions, when I was in school my teachers hated me! fortunately over teh years I have managed to anser many of them myself but some seem to be beyond my ability. Thanks for the help dudes and dudettes

Michael

Michael

[Jay-qu]

Your looking for a number right? Why not 3, I can confirm what Boerseun said that the habitable zone extends from around venus out to around mars - but depends on the size and composition of the atmosphere. As we can see in our system we had 3 planets form in this narrow band - do you think its likely that a 4th could be squeezed in and still remain stable? I dont think so.. but I dont have to maths to back up this guess lol so it remains just that - a guess.

[Boerseun]

It could very well be only three or four.

Seems that between Mercury, Venus, Earth and Mars, these four relatively small planets swept up all the available matter in the inner Solar System. The sun started shining and the resulting solar wind blew all the lighter gas to the outer Solar System, where the physical availability of much more matter (seeing as their orbital distance is much longer than the inner orbital planets) resulted in much bigger planets. Seems that Jupiter's gravitational proximity is sufficient to stop a fifth inner planet from congealing (the asteroid belt).

But the four that was created, was created with the available matter and heavy elements that was left over after the solar wind started blowing. There simply isn't enough sizable matter left to build another planet, and the only stuff left (the asteroid belt) that could conceivably do the job, is denied the opportunity because of Jupiter's proximity.

Many more planets can conceivably fit into stable orbits in the inner solar system, but the question then will be, if you're discussing a sun-like star with a sun-like evolution, where would those planets have come from?

[Moontanman]

Originally Posted by CraigD

This PNAS article gives a an overview of the question of the stability of solar system in general. There are many others. Searching for “stability orbit” produces a long list. I recall some good treatments in popular science magazines such as Scientific American, and in books such as James Glick’s “Chaos”.A survey of the literature on the subject, or writing and running your own long-duration gravitational simulations, reveals this to be a difficult problem, and suggest that “stable” is only a relative term. Fairly convincing simulations suggest that, over very long time frames (billions of years), very few orbital systems are stable. One of the great challenges of orbital simulations modeling the solar system is, in fact, getting the model to match observed data – most of them have the solar system ejecting the inner planets, while the giants spiral into increasingly tight orbits, resembling many of the extra-solar systems that have been measured.

Papers such as the PNAS article above note that orbital resonance – that adjacent orbiting bodies complete small, nearly whole numbers of revolutions in the same time period (eg: 1:2, 2:3, 3:5) - is an important factor in determining stability. Although resonance is found strongly in the moon systems of Jupiter and other giant planets, and weakly in inner and outer planets, this doesn’t appear to be the dominant factor in an explanation why the solar system is so stable (quick reference to planetary orbit data: Table of planets and dwarf planets in the Solar System - Wikipedia, the free encyclopedia).

Key to the whole solar system’s stability – including the inner planets - seems to be the preservation of the orbits of the giant planets. Key to this appear to be their acquisition of kinetic energy from gravitational interaction with small, irregular-orbit bodies (comets and other Kuiper belt objects). These many bodies seem to function somewhat like a storage battery to “keep the giant planets running” by their occasional “sacrifice”. However, since interactions between the giant planets and these stray bodies appears, to a simple analysis, to be as likely to take kinetic energy from the larger body as give it, mystery remains.

From my read and work on the question, I’ve come to consider the long-term stability of orbital systems like the solar system a hard problem. Unfortunately, it doesn’t seem one amenable to simple, elegant theories, but one that requires a lot of intense number crunching and ad-hock explanations.I can’t recall such a theory, but imagine, based on the complicated but apparently stable interactions of giant planet moons, that there could be many planets in circular orbits close to Earth’s, at Lagrangian points, “shepherding” or otherwise complicatedly interacting with one another. Theories such as the giant impact hypothesis for the formation of the Moon suggest that the inner solar system may have once been like this, but that such arrangements aren’t stable, evolving over time into what we observe now.

All-in-all, this is a big, messy problem, likely IMHO to require lifetimes of work and lots of computing power to answer with confidence.

After visiting the wikipedia link shown in this letter, Table of planets and dwarf planets in the Solar System - Wikipedia, the free encyclopedia).
I noticed a problem, the diameters of the planets given kilometers is completely in error. The Earth is not 6,000 or so kilometers in diameter, it is a little over 12,000 kilometers in diameter. All of the other planets would seem to suffer this problem as well. I have seen this problem many times with this so called information source. If I hadn't been doing some real comparison work I might not have noticed. If someone who didn't know at least the approximate diameters of the planets hadn't seen this they would have assumed it was correct. I never assume wikkipedia is correct, even in things that should easily have been checked much less things that are less obvious. I know you were just using this as source and I don't fault you but Wikipedia is weak place to get source material. I stay away from it as much as possible just for this reason.

Michael