Planets outside our solar system may be more hospitable to life than thought, research suggests

Jan 25, 2015

Credit: © marcel / Fotolia

By Science Daily

A study by astrophysicists at the University of Toronto suggests that exoplanets — planets outside our solar system — are more likely to have liquid water and be more habitable than we thought.

“Planets with potential oceans could have a climate that is much more similar to Earth’s than previously expected,” said Jérémy Leconte, a postdoctoral fellow at the Canadian Institute for Theoretical Astrophysics (CITA) at the University of Toronto, and lead author of a study published today in Science Express.

Scientists have thought that exoplanets behave in a manner contrary to that of Earth — that is they always show their same side to their star. If so, exoplanets would rotate in sync with their star so that there is always one hemisphere facing it while the other hemisphere is in perpetual cold darkness.

Leconte’s study suggests, however, that as exoplanets rotate around their stars, they spin at such a speed as to exhibit a day-night cycle similar to Earth.


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15 comments on “Planets outside our solar system may be more hospitable to life than thought, research suggests

  • hairybreeks Jan 26, 2015 at 4:34 am

    Scientists have thought that exoplanets behave in a manner contrary to
    that of Earth — that is they always show their same side to their
    star.

    Citation?

    We would indeed need some evidence if anyone is to challenge that the laws of gravity and conservation of momentum are going to cause tidal locking!

    Sychonicity soon becomes a problem for the climate of any planet which orbits close to its star.

    https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Tidal_locking.html

    http://en.wikipedia.org/wiki/Tidal_locking



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  • This confused me as well as it makes it sound like all earth like exoplanets behave differently to earth. But if you read the Popular Mechanics article I linked I think the point is that earth like exoplanets around red and orange dwarf stars that are in the habitable zone are likely to be tidal locked. Red and orange dwarves also apparently have a lot of the earth like exoplanets.

    If you’re on the hunt for Earth-like planets that can sustain life,
    then your best bet might not be stars that look like our sun, but
    smaller, cooler stars—orange and red dwarfs. These, on average, have
    been found to host more Earth-sized planets, and they are far and away
    the most abundant. They make up more than 75 percent of the stars in
    our universe, and nearly every red dwarf star has at least one
    exoplanet.

    But there’s a potentially fatal flaw here: When exoplanets orbiting
    these stars are the right distance to hold liquid water, they tend
    suffer from what astronomers call rotational lockup.



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  • To me the notion that we are the only inhabited planet is absurd. I am expecting confirmation within my lifetime that life is like dandelions and infects nearly every one of the trillions of places capable of sustaining it. Why else would life have evolved the ability to take deep space voyages?

    I wonder how mankind will react to the news.

    will they just deny it?
    will it make them more humble, realising their God has plenty more to occupy him than them.?
    Will they say “that does not count”, only technological life counts.
    When we learn how fragile life is , and how often planetary life goes extinct, will we smarten up about caring for our planet? Or will we become more careless, knowing we can’t extinguish all life.



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  • The likelihood of life on millions of other planets at bacterial or self replicating chemical level is inevitable, and possibly detectable in our immediate proximity.

    For that life to develop in complexity to the extent it did on this planet between the Cambrian epoch, and the late Eocene is less likely., even given the inevitability of evolutionary pressure, requiring as it does very specific planetary circumstances.

    For that complex life to develop into a self aware and intellectually questing, technically capable species is less likely again, but that does not mean it has not, or is not, or will not, happen..

    For that to happen, and develop technically to the point that, given light travel time, we could become aware of them would assume that the timing of the existence of our two species is coincident, again considering the implications of light travel time, is even less likely still.

    While the existence of such species is probable, given the incomprehensible number of opportunities for it to happen, for us, or them, to be ever be aware of each other is the most highly unlikely of circumstances.



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  • mmurray Jan 26, 2015 at 5:18 am

    This confused me as well as it makes it sound like all earth like exoplanets behave differently to earth. But if you read the Popular Mechanics article I linked I think the point is that earth like exoplanets around red and orange dwarf stars that are in the habitable zone are likely to be tidal locked. Red and orange dwarves also apparently have a lot of the earth like exoplanets.

    I remain sceptical.
    Habitable zones do not only depend on average temperatures, but also on extreme ranges of temperature.

    It is all well and good suggesting that an atmosphere and oceans would distribute heat around the globe, but once the temperature ranges reach levels where oceans boil in the sun, and atmospheres freeze out in the dark, it looks very dubious.

    There is a second problem:- that if a potentially habitable globe, was orbiting a large planet in a habitable zone, proximity to a star makes it increasingly difficult for a planet to retain moons, – because of the stronger gravity on the sun-ward side of the orbit and the weaker gravity on the opposite side distorting the orbit until the moon crashes into the planet at perigee, or is lost at apogee.
    (That is why it is impossible for Mercury to retain a moon.)



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  • I think they are suggesting that the atmosphere actually causes the planet not to lock not that it is just redistributing the heat.

    Leconte and his team reached their conclusions via a three-dimensional
    climate model they developed to predict the effect of a given planet’s
    atmosphere on the speed of its rotation, which results in changes to
    its climate,” said Leconte. “Atmosphere is a key factor affecting a
    planet’s spin, the impact of which can be of enough significance to
    overcome synchronous rotation and put a planet in a day-night cycle.”



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  • mmurray Jan 27, 2015 at 7:00 am

    I think they are suggesting that the atmosphere actually causes the planet not to lock not that it is just redistributing the heat.

    I could be wrong, but a number of factors look dubious.

    First – The small Red dwarf stars have goldilocks orbit zones quite close to be warm enough, so tidal locking drag is considerable.

    Second – thin atmospheres lack mass especially compared to tides in magma* and oceans.

    Third – starlight as an energy input, sounds pretty weak, to compete with tidal drag in atmospheres and oceans, or with the solar heating on the sun-facing hemisphere.

    Fourth: Unless they are suggesting some difference of air-flow predominantly in the direction of rotation, rather than winds slowing planetary rotation, or being neural, the argument of starlight energising atmospheric expansion v tidal drag and solar heating expansion, looks weak in any close orbit.

    There may be all sorts of weak effects from light on bodies further out from stars (as for example, re-radiated solar heating deflecting asymmetric asteroids in their orbits) but for habitability, this needs to be tied to the close orbits where goldilocks zones exist around Red Dwarfs.

    *The issue of magma is also relevant, as without atmospheric volcanic recycling, planets (like Mars) solidify and die.

    Tidal drag – is of course a prime mechanism for breaking up crusts, maintaining a fluid core and volcanism – especially on small planets and moons (Earth’s additional long-lasting heat, appears to have come from the giant collision of the Earth-Moon formation.)



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  • It depends on what counts as “life”. I’d be willing to bet that cells and precursors exist in abundance on other planets, since on Earth they were not only the first but also remain the most abundant and diverse of living things. Multicellular life is probably less abundant as a consequence of this dependency on unicellular life and lack of versatility, and human-like life is probably close to non-existent.

    Even on Earth, which we supposedly “dominate”, the human species is a comparatively destructive flash on the veneer of the multicellular mass of the biosphere. I’d be more optimistic about our driving blind if there weren’t so many times when we thought driving recklessly was a good idea. That suggests evolution needs a pretty large amount of coaxing to produce something like us, and even then I can’t say I’m confident in our long-term survival – by which I mean on evolutionary timescales.



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  • mmurray Jan 27, 2015 at 7:00 am

    I think they are suggesting that the atmosphere actually causes the planet not to lock not that it is just redistributing the heat.

    One interesting example of a close orbiting body with an atmosphere and weather, is Saturn’s moon Titan.

    Titan’s rotation period of about 16 days is synchronous to Saturn (meaning the same side always faces Saturn). It is the only moon in the Solar System known to have clouds and a thick, planet-like atmosphere. http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens/Facts_about_Titan

    Atmospheric pressure at surface 1500 mbar (1.5 times Earth’s)



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  • Only time will tell whether we are alone in the universe, but as interstellar distances are so vast and the necessary conditions for microbiotic life to exist – let alone complex, intelligent, multicellular life such as our own – so improbable, I think it is safer to assume that there is no advanced lifeforms within at least a couple of million light years of our own galaxy. We’ll just have to keep looking.



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  • Ipse Dixit Jan 28, 2015 at 6:46 pm

    Only time will tell whether we are alone in the universe, but as interstellar distances are so vast and the necessary conditions for microbiotic life to exist – let alone complex, intelligent, multicellular life such as our own – so improbable, I think it is safer to assume that there is no advanced lifeforms within at least a couple of million light years of our own galaxy. We’ll just have to keep looking.

    I think the only chance of approaching any planets at present outside the Milkyway, will be when the Milkyway and Andromeda galaxies collide in somewhat over 4 billion years – if humans can manage to to exterminate themselves in the next few thousand!

    Meanwhile, I think you are right about the chances of intelligent life being anywhere near us, are remote – particularly because of the “Rare Earth Hypothesis”.

    However, the types of stars with high metalicity planets which have the right elements for evolving simple life, come in clusters, and we are in one of them, so it is just possible that planets outside the Solar-System with some life forms, or which could support Earth-life, may be just about within the range of possible future space craft.



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  • Meanwhile, – back in the Solar-System the exploration of dwarf planets continues.

    http://www.bbc.co.uk/news/science-environment-31754586

    .The US space agency’s Dawn probe has gone into orbit around Ceres, the largest object in the Solar System between Mars and Jupiter.

    A signal from the satellite confirming its status was received by ground stations at 13:36 GMT.

    Ceres is the first of the dwarf planets to be visited by a spacecraft.

    Scientists hope to glean information from the object that can tell them about the Solar System’s beginnings, four and a half billion years ago.

    Dawn has taken 7.5 years to reach its destination. Its arrival has seen it pass behind the dwarf to its “dark side”.

    Over the next month, controllers will re-shape the orbit to get it ready to begin the prime science phase.

    And over time, the intention is to progressively lower the orbit until the probe is just a few hundred km above the surface.



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