Pack your bags! Astroboffins spot 24 'superhabitable' exoplanets better than Earth at supporting complex life Astrobiologists have found 24 exoplanets that, compared to Earth, may have environments better suited to complex life like that found on our world. A team led by Dirk Schulze-Makuch, a professor at the planetary habitability and astrobiology at the Technical University Berlin, devised a checklist of requirements that an alien …
It's a long time since I was at school - but wouldn't an atmosphere containing significant amounts of oxygen be considered an actual indicator of life? What with oxygen being so reactive, I vaguely remember that if you don't have something actively replenishing it in the atmosphere it rapidly ends up locked into metals on the crust.
On Earth, photosynthesis is that process, courtesy lots of plants on land and sea. But maybe I'm being needlessly carbon-hydrogen-oxygen chauvinistic here, and there are non-life mechanisms that can maintain a large oxygen atmosphere?
Well indeed. Cyanobacteria here didn't find it too friendly. But the article made the point that oxygen atmospheres were what the search was looking for.
Parenthetically - while it is possible that oxygen-based metabolisms aren't the only ones out there, it is one that we know for certain can maintain a macro-biology.
Advanced life needs that high energy that comes from oxidation.
Why? That is still unconscious anthropomorphism. High levels of activity require high levels of power, but it's perfectly possible to imagine an intelligent species that takes a year to say "hello", and for whom the day/night cycle is akin to the flickering of fluorescent lighting. That could imply a metabolism and power requirements that we would consider unfeasible.
At the other end of the scale it has been seriously proposed that entire civilisations could evolve, rise and fall in what we consider the blink of an eye in extreme environments such as the atmospheres of neutron stars.
Re: Advanced life needs that high energy that comes from oxidation.
I think the idea is that the more complex life is, the more specialised the individual cells are, and the closer together they are. This may require high energy consumption to maintain life which cyanobacteria are unable to maintain.
Phoyochemical disassociation, where ultraviolet radiation from the sun causes water to split into hydrogen and oxygen, can cause small amounts of oxygen to be sustained in the atmosphere. According to the below listed source, about 2% of the earth's current oxygen comes from this process. But photosynthesis creates all but a minute amount of the rest of the free oxygen molecules.
http://www.thisoldearth.net/Geology_Online-1_Subchapters.cfm?Chapter=8&Row=3
I remember being at school in the mid 80s, and my science teacher explaining to us that the planets in our solar system were the only known ones, we did not know for sure that others existed around other stars, though it seemed very likely considering we had nine (not eight, it was the 80s).
He also explained how it would be physically impossible to see planets around other stars even with a huge telescope, they were simply too far away and too small, dark to be seen right next to huge bright stars, so we probably wouldn't know until we sent probes there. And because of the vast distances, the probes could take centuries to arrive, and their reports back years or decades to return. So even our grandchildren probably still wouldn't know.
And then about 10 years later, we started finding exoplanets, and now 30 years or so on, we have a big list of rocky, earth-sized ones, we can even tell if they have atmospheres, and what the atmosphere contains, whether they have water and magnetic fields.
Science is quite astounding at achieving what was only a few years ago considered impossible.
If we're inventing magic FTL, I've also invented a shield dingus that harmlessly funnels those particles into the drive as fuel. But yes, nipping through a friendly wormhole might be easier. Using Gay Deceiver even more so
"how the heck do they measure that so accurately from so far away anyway?"
They don't. From the paper:
"Current technology simply does not allow us, for example, to measure global temperatures on extrasolar planets anywhere close to the accuracy needed."
The temperatures are actually little more than guesses based on several entirely unsupported assumptions about what the planets might possibly be like. For example, the one quoted as having the "most Earth-like temperature" comes from this paper https://doi.org/10.1051/0004-6361/201936929 which says:
"We find that the stellar radiative energy flux of the new transit candidate would be times the insolation atthe top of the Earth’s atmosphere. An Earth-like Bond albedo of 0.3 would result in a globally averaged surface temperature of about K... hese calculations neglect the additional heating of the greenhouse effect, for instance, from water vapor (H2 O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone (O3), and other greenhouse gases. On Earth, the greenhouse effect amounts to about + 33 °C. If the transit candidate signal belongs to a genuine planet and if this planet has an atmosphere that provides an Earth-like greenhouse effect, then the globally averaged surface temperature is around + 5 °C."
In other words, if the surface is very similar to Earth's, and if the atmosphere is very similar to Earth's, and if the radiation received from its star has been calculated correctly, and if there's actually a planet there at all, then the temperature will fall somewhere in the estimated range. The actual detection method used, looking at variation in the star's brightness due to possible transiting planets, cannot provide any of this information, it's all pure guesswork about what things could be like given the best possible assumptions for life. Which is why it's a very minor part of that paper, it's actually about the detection of the planets and speculation about their possible properties is just a small side note.
As for the original paper, the headline of this article is extremely misleading. Astroboffins haven't spotted anything. The paper is simply an analysis of already known planets, trying to assess their potential for habitability using criteria decided by the authors. It doesn't add any new information, it's really just saying something along the lines of "Here's a way of looking at the information we already have in a way that might be interesting, and here's the additional information we would need in order for it to actually be useful". There's no new discovery, or even anything particularly interesting going on, just some ideas about what we might like to know once we have better technology and techniques for looking at things.
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Rotational stability is probably important for land-based life, but oceanic life probably doesn't care too much, so it probably comes down to how much water there is on the planet in question.
We get the benefit of Jupiter protecting us from occasional visitors from the Oort cloud, but do we know that other solar systems have Oort Clouds?
These are things that help make Earth suitable for complex life, but it's a bit hubristic to assume they are requirements.
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Don't you think that sea life might well be upset if the planet's axis tipped over by 90 degrees? What's more, the large moon churns it all up twice a day, which might be a good idea to get life going.
Given that such things aren't thought to happen quickly in bodies that are not tidally locked (we're thinking along the 10ka sort of time scale IIRC), anything swimming around freely is going to care not one jot.
Tides are important where there is coast, and mostly so for intertidal organisms. Something like Architeuthis that is swimming around a mile under the water's surface isn't going to notice the top of the water column going up and down by a metre or two.
As for the Anthropic Principle; I've never found it to be particularly helpful. The weak principle effectively says, "we exist here because the conditions here are suitable for the sort of life that would evolve here," which seems more than a tad tautological to me. The strong principle effectively says, "the conditions here are so suited to life that they must have been made that way just for us," which is not only a leap of faith (and I choose that word carefully), but also tending towards magical thinking.
In general terms, I think it is more helpful to say that if the conditions exist that are suitable for a "thing", and a mechanism also exists for that "thing" to come to be, then sooner or later that "thing" will evolve to fit that niche.
Life exists on Earth because there are suitable energetic and chemical gradients to allow the complexity to evolve and sustain itself. Similar conditions no doubt exist across the universe. The one thing we don't know enough about is how easy it is for life to get started (we only have one case study, and the genesis of terrestrial life is shrouded by time, and the pesky habit of the Earth's to recycle its crust so that fossils from that time are no longer around). Life may take many different forms, although it would be constrained by what is chemically, or energetically possible. Being on a celestial body that is relatively stable in terms of temperature, pressure and energy input is obviously going to be a big part of its sustainability. Our planet is in a stable orbit around a suitable star (there are lots that aren't such as variables, or ones prone to ejecting large flares), has a moon to help stabilise its orbit and tides, and Jupiter as a shield to soak up stray space rocks. This isn't always 100% effective of course (look up "Late Heavy Bombardment"). This creates an "island of stability" where life has flourished and evolved. Just because that "island" provides a suitable environment on Earth, however, does not presuppose it is the only "island" that can exist, and we have to be careful in drawing such conclusions. It can help us if we are looking for other similar conditions elsewhere, of course, by giving us a "leg up", but we shouldn't let us overlook other places that otherwise would be "interesting".
Without a very large moon to keep its rotation stable, and also huge great gas giants in the system to stop comets, I expect the aliens will have large hands and feet, enabling them to stay on the surface, and a very hard exoskeleton so that comets and meteors just bounce off them.
"A higher average surface temperature would also lead to a warmer humid climate that supports higher levels of biodiversity,"
Oh good, the way things are going we will soon be up to our ears in new life forms.
Thank you fossil fuels.
It might not be so good getting there though.
"though bear in mind all of them are at least 100 light years away."
Light doesn't travel in a straight line.
Look up at the night sky. See the star up there, so far far far away? 100 light years away, in a straight line?
Light doesn't travel in a straight line, that star might be behind you and a damn site closer than it appears, with the light taking a curved path around the universe before reaching us. You perceive the curve as if it was a long "straight" path. (Where straight is the local perception of the local motion of light over short distances extrapolated to huge distances.)
It's frame dragging, you already know it on the outside of the black holes. It's on the inside of the black hole too. We're on the inside of a black hole, you can tell that from the boundary in our universe (the apparent edge of the visible universe and the apparent bounded 'age' of the universe).
I'm not sure how useful it is to know that, since everything is propagating over that same field, but if you're wondering about the weird geometry of the universe, why you cannot map the "furthest" objects as if they were a bubble, why it has a boundary (both distance and time), and why its expanding at a non-constant rate, perhaps that realization might help.
(Nice shadow wobble, BTW. Thx.)
Which, in turn, will have an impact on the maximum height of any multicellular organism out there.
I'm no boffin myself, but I have read many articles on how King Kong could not possibly exist because the mass ratio to bone thickness would mean his skeleton couldn't possibly keep him standing, and other articles to that effect.
So, I'm all for superhabitable and I get that it means there may be life there, not that we can live there, but a larger planet means smaller creatures. At 1.25 times the mass of Earth, any dinosaur out there would not be as tall as the Brontosaurus, I'd guess.
> Which, in turn, will have an impact on the maximum height of any multicellular organism out there.
Yes, but so does the oxygen content. More O2 => bigger creatures.
I'd be interested to see the plot of O2 vs gravity vs creature size... Bit difficult to run that experiment at the moment, though
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Earth's G-type sun will only last about 10 billion years
Not a huge problem for life on Earth, that'll be long gone.
The molten core of this rock is cooling, in under 100 million years it'll be solid all the way through which means the magnetic field will be just a memory and the planet will get its full share of solar wind stripping the atmosphere and turning the Earth into a larger version of Mars.
In the hugely unlikely event of Mankind lasting into the deep future, it might be possible to artificially deflect the solar wind using something like a fixed Bussard collector.
Of course in space nothing is as simple as it seems, Venus does not have a molten core but retains an atmosphere, her ionosphere is sufficiently highly charged to deflect the solar wind.
We also have to accept that:
[a] we're a transient species even here, just like all other species, so the cooling Earth and the life of the sun are probably not significant to us. Life of some sort will probably exist here long after humans are extinct, so these will be their problem, not ours;
[b] even if we could get to such an idyllic planet 100 light years away, we'd probably find it fully occupied already.
"...we'd probably find it fully occupied already."
If, perchance, they are less *civilized than whatever we currently attach that word to... it'll be the whole Christopher Columbus -vs- aboriginal Americans thing again, and if they are more advanced that we... perhaps we'll not be allowed to get close enough to find out.
Hmm, last time I looked there were several and there was a consensus on around 90 my but now I look it seems the consensus has altered from millions to billions to 90 by - initially probably a typo on one which got copied to others.
OK, I screwed up on that one, actually believing stuff on the Internet without checking more than 2 or 3 independent sources.
It seems there is no real consensus on just how fast the core is cooling as there are too many unknowns regarding not only the actual composition but the physics at those pressures. At the moment there is nothing like a definitive answer. https://eos.org/features/earths-core-is-in-the-hot-seat
I wonder if I could get an Orion class spaceship crowdfunded?
Then after a shakedown run to Saturn and back you set off to KOI 5554.01. As even if you could accelerate to 10% of the speed of light it would still take 7000 years to get there, I would go for the biggest "Super Orion" model.
As Carl Sagan pointed out, it would be a good contribution to nuclear disarmament.
> As even if you could accelerate to 10% of the speed of light it would still take 7000 years to get there
I've (hopefully) got good news for your project - if it's only 701 light years away, and you can get to 10% of the speed of light toot-sweet, you will experience a mere fraction of that travel time in your metal Mayflower. Just 6,940 years. Thank you, Einstein.
So much for colonizing a heavy gravity world. It's hard enough to get off this 1g world. Much higher, given the fuel load required, it would be net to impossible to lift off with a usable payload.
As to the hot climate... uhm... aren't we at issue with that here? Just say'n.
As to the microbial life, if it lives in a similar environment to us, how likely is it that their microbes and our microbes will hold a jam fest and give us a nice round of super duper bugs to fight off. Small Pox 2.0...
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Surely one of the problems with a higher planetary mass creating a denser atmosphere is the likelihood of a runaway greenhouse effect? Sadly I cannot find the reference, but I'm sure I heard recently that the impact which created the Moon also removed much of the proto-Earth's atmosphere. If that had the effect of preventing a runaway greenhouse effect, then just having a planet in the 'Goldilocks zone' may not be enough for complex life, it might need a major event to avoid ending up with an atmosphere like Venus' and similar temperature and pressure on the surface.
BTW, interesting article on the New Scientist web site:
https://www.newscientist.com/article/2256156-an-earth-sized-rogue-planet-is-roaming-the-galaxy-without-a-star/
I trust everyone has read H G Welles' short story "The Star"?
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