Super-Earths are ideal targets in the search for
divbzero 5 days ago [-]
> If a super-Earth is ejected from its star system and has a dense atmosphere and watery surface, it could sustain life for tens of billions of years, far longer than life on Earth could persist before the sun dies.

What would be the energy source to sustain life on an ejected super-Earth? Radioactivity? Tidal forces from orbiting moons?

njarboe 5 days ago [-]
This seemed off the me also. Reading through the paper quoted in this sentence makes it clear that the sentence is just wrong. From [1]:

"The team found that planets 10 times the mass of the Earth, with an atmosphere 100 to 1000 times thicker than Earth’s, may be the most favorable for storing life for billions of years. But to do this, they must orbit the star at a distance that the orbit of Mars occupies in the Solar System. At such a potentially safe distance, the original atmospheres can act as greenhouse gases, absorbing infrared radiation, providing the necessary heat and pressure that can support life in oceans of liquid water."

So the planet is not ejected from the system, just pushed out so that instead of an orbit of days it is as far away as Mars is to our sun (1.5 AU). Gell-Mann Amnesia comes into play here.


divbzero 5 days ago [-]
Thanks for spotting that link.

Digging one link farther reveals the original article [2] which is more detailed and descriptive than the others. The original article explores super-Earths where the primordial H–He atmosphere is retained and traps enough heat to sustain liquid water, and includes simulations of “unbound” super-Earths that are ejected from their star systems. The mathematical model [3] incorporates the initial heat from planet formation and radiogenic heat but does not mention tidal forces.




The original article also includes this discussion of habitability:

Life on the type of planet described in this work would live under considerably different conditions than most life on Earth. The surface pressures in our results are on the order of 100–1,000bar, the pressure range of oceanic floors and trenches. There is no theoretical pressure limit on life, and some of the most extreme examples in Earth’s biosphere thrive at ~500bar. These habitats also receive a negligible amount of direct sunlight, and therefore photosynthesis would not be an optional mechanism to provide for metabolism. Chemoautotrophic life on Earth would be a more likely analogue to possible life on this type of planet.

5 days ago [-]
ReptileMan 5 days ago [-]
Just to point that water is almost exactly 1000 times thicker than air Edit: 800 times if we have to be precise
mr_toad 5 days ago [-]
I don’t think we’re exactly sure how much of the Earth’s heat is due to radioactive materials in the core or just left-over heat from its formation, but either way a super Earth should have more of both.
hinkley 5 days ago [-]
One of the early pieces of evidence for the existence of radioactivity had to do with the fact that the Earth’s core is way too hot to be billions of years old. Even if there were coal veins down there just burning slowly forever.
tambourine_man 5 days ago [-]
Yeah, I wondered about that as well. It must be radioactive and residual heat from the core.

I can’t imagine geothermal supporting as vibrant an ecosystem as photons pouring in everyday allow photosynthesis to do.

ramraj07 5 days ago [-]
I suppose one cannot expect anything better from a site called singularity hub, but this post is disingenuous (or written by an actual hack) for multiple reasons. Aren’t the majority of planets we are discovering all orbiting red dwarfs, which can exhibit massive swings in luminosity and be very violent? Even the example quoted by the author which such a short radius seems one of them. Also what do you do in a tidally locked planet? Half if not 90 % of it is likely to be unsustainable.

Also a rogue planet without a star might be able to sustain simple life but without human sources of nuclear power the only source of energy would be geothermal, so not exactly exciting candidates for living. Also who wants to live in a planet in perpetual darkness?

Either the “astronomer” author wasn’t a real astronomer at all or this is just clickbait.

sbuttgereit 5 days ago [-]
"Chris Impey is a University Distinguished Professor of Astronomy at the University of Arizona. He has over 210 refereed publications on observational cosmology, galaxies, and quasars, and his research has been supported by $20 million in NASA and NSF grants. He has won eleven teaching awards and has taught two online classes with over 300,000 enrolled and 4 million minutes of video lectures watched. Chris Impey is a past Vice President of the American Astronomical Society, and he has won its Education Prize. He’s also been an NSF Distinguished Teaching Scholar, Carnegie Council’s Arizona Professor of the Year, and a Howard Hughes Medical Institute Professor. He has written 70 popular articles on cosmology, astrobiology and education, two textbooks, a novel called Shadow World, and eight popular science books: The Living Cosmos, How It Ends, Talking About Life, How It Began, Dreams of Other Worlds, Humble Before the Void, Beyond: The Future of Space Travel, and Einstein’s Monsters: The Life and Times of Black Holes."


Naturally, none of this makes him right... I have no judgement on that point. But does clear some of the ad hominem.

ramraj07 5 days ago [-]
Which is more ad hominem - I only judged the author by what they wrote. Pointing out they’re a professor sounds more like we need to trust them because of who they are.

one could say his career depends on selling this idea that these exoplanets are awesome sauce. Maybe it’s even worse?

pc86 5 days ago [-]
I imagine in career depends much more on his peer-reviewed publications and teaching (almost certainly in that order) than on this blog post or one of his presumably many theories.

> Either the “astronomer” author wasn’t a real astronomer at all or this is just clickbait.

Well it turns out he is a real astronomer, and doesn't appear to be a "hack" either as you also said he was.

ramraj07 5 days ago [-]
So he is an astronomer, thus just merely disengenous. I suppose that’s more comforting to you?
dhruval 5 days ago [-]
Sorry for in advance for the dumb question...

Are red dwarf planets over represented due to detection methods?

Or is there some sort of astrophysics related reason red dwarfs would be more likely to have super earth class planets in orbit?

Basically should we hold out hope that with better detection techniques we will be able to detect more planets that are similar to our own.

ramraj07 5 days ago [-]
My understanding is it’s a combination of both - red dwarfs are the most numerous and super earths are the most easiest to detect with them (smaller star, larger the effect of the planet on its characteristics and luminosity).

I am also convinced we will find planets better suited for us than earth eventually. But I doubt any of them would be in any meaningful close distance.

Even if you can imagine a 100 year or 500 year ship (like in Expanse) that can get to a planet 10 LYs away, imagine if it’s 100 or more. We might be SOL.

bagels 5 days ago [-]
Better suited in what way? Humans are pretty well adapted to Earth specifically.
midoridensha 5 days ago [-]
Humans are well adapted to the Earth of thousands of years ago, up until the 1800s or so.

The Earth of the future, not so much.

SamPatt 4 days ago [-]
The rapid expansion of human population since 1800 challenges this claim.

We don't need an ideal climate to flourish. That's part of our species' strength: our remarkable ability to adapt.

midoridensha 2 days ago [-]
Humans aren't going to be able to adapt to an irradiated wasteland.
Thiez 5 days ago [-]
Sure, depending on how far you want to go into the future, eventually the sun will grow so bright that all our water will boil away... but barring a catastrophe that destroys (almost) all life (nearby supernova, collision with a large space rock, ...) I'm pretty sure that earth will remain more hospitable to human life for tens of thousands of years than any planet we will find.
ramraj07 5 days ago [-]
More space? Less extreme weather? Lots of accessible mining? Etc
jabbany 5 days ago [-]
> Also who wants to live in a planet in perpetual darkness?

I'd guess in that case people would be living underground in artificially lit environments...

This idea has already been explored by sci-fi. One instance that comes to mind is Wandering Earth where the premise is that people turned the Earth into a planet scale space vessel to escape the sun's expansion and "rehome" the Earth. I'd suggest reading the book rather than watching the movie based on it though.

njarboe 5 days ago [-]
The sentence:

"If a super-Earth is ejected from its star system and has a dense atmosphere and watery surface, it could sustain life for tens of billions of years, far longer than life on Earth could persist before the sun dies."

is wrong according to the article it references in support. See this comment for details[1].


denton-scratch 5 days ago [-]
Yeah, either you orbit at a safe distance, or you get ejected and become a rogue planet.

I'm rather taken with this idea of billions of rogue planets, wandering around the Milky Way, carrying life that's billions of years old. Such a rogue might get captured by a star-system's Oort cloud, gradually drift towards the star, and eventully evince more complicated life. In fact I'm not aware of strong evidence that Earth isn't a rogue (it's about the same age as the Sun, but that's circumstantial, right?)

saiya-jin 5 days ago [-]
Also I would expect the amount of cosmic radiation bombarding the surface outside of star's envelope would be significant. We on Earth are extremely lucky that we have molten metallic rotating core (possibly done by collision with another planet/moon very long time ago, not 100% sure here), but that's not the default for planets.

So yes life can be probably only sub-surface one, but that's generally a tough proposition living off what... geothermal vents and volcanic activity? That's hardly a recipe for anything advanced, regardless of time given to evolve.

rbanffy 5 days ago [-]
Well… Suitable for life is not synonymous with convenient for humans. For one, a super Earth makes space exploration much harder - Earth itself is very hard to leave with chemical rockets alone.
mod 5 days ago [-]
If you're calling out the claim in the article, I'd just provide some counter-evidence.

But no, they specifically said most of them are not orbiting red dwarfs:

> Most super-Earths orbit cool dwarf stars, which are lower in mass and live much longer than the sun.

ramraj07 5 days ago [-]
What exactly is a cool dwarf? Doesn’t seem to be a real category - there seems to be one called ultra cool dwarves which is a subtype of red dwarf stars including TRAPPIST-1. Doesn’t exclude the tidal locking problem, but can’t confirm if they are more immune to solar variability and storms.

Also apparently the planets will never be brighter than sunset in earth. The author could have at least mention some of the potential problems. I stand by calling this article disingenuous.

wahern 5 days ago [-]
> they specifically said most of them are not orbiting red dwarfs:

The statement, "scientists have found super-Earths orbiting 40 percent of cool dwarfs", specifically links to an article discussing red dwarfs: That article quotes the author of an ESO HARPS planetary survey paper: “[o]ur new observations with HARPS mean that about 40% of all red dwarf stars have a super-Earth orbiting in the habitable zone where liquid water can exist on the surface of the planet".

Cool dwarfs seems to be a direct reference to red dwarfs.

NotACop182 5 days ago [-]
Imagine being intelligent life on a super earth 2.5-3x larger than earth but trapped on the planet due to gravitational forces.
eigenhombre 5 days ago [-]
Being already semi-intelligent, and trapped here, also due to gravitational forces, I think I can sort of imagine it.
NotACop182 5 days ago [-]
Yea but our civilization can still make it to orbit. It would be very very hard for them to leave the planet.
anothernewdude 5 days ago [-]
I don't think Human civilization ever leaves this solar system. The Fermi Paradox isn't a paradox for me, it's about what I'd expect.
stackbutterflow 5 days ago [-]
Does it mean they can't use ICBM? That's sound like an advantage to avoid self destruction.
was_a_dev 4 days ago [-]
Mankind would find, and has found, plenty of ways to self-destruct without ICBMs
dreamcompiler 4 days ago [-]
ICBMs would still be possible -- but perhaps with more limited range.
metamet 5 days ago [-]
Ah, so this is why they haven't visited earth yet.
rizzom5000 5 days ago [-]
It's also why they wouldn't have orbiting satellites which would be incredibly useful for both exploration and communication systems.
NotACop182 5 days ago [-]
a rocket on a super-Earth would need to have a mass of about 440,000 tons (400,000 metric tons), due to fuel requirements, the study said. That's on the order of the mass of the Great Pyramid of Giza in Egypt.

Just imagine the effort to get one satellite up. Now this would open the door for them to find new ways to make it to orbit.

denton-scratch 5 days ago [-]
rbanffy 5 days ago [-]
It would also strongly motivate the inhabitants of the planet to permanently leave it.
denton-scratch 4 days ago [-]
Yeah, I know! I didn't mean to suggest it was a good idea. But if you want to get The Great Pyramid of Giza into space, that's how you'd have to do it (i.e., it's possible in principle).

I think the Orion project people spoke of a spaceship the size of a large hotel; with plenty of lead for screening cosmic rays. They claimed there'd be so much lifting capacity that keeping weight down wouldn't be an issue - you could have a barbershop with real barber's chairs.

I don't see much future in this kind of design. But I also don't see much future for human space exploration without truly gigantic spaceships. I suppose the alternative is to assemble the ship in orbit, using hundreds of chemical-powered supply missions.

NotACop182 2 days ago [-]
Love to see what a failed liftoff looked like
hinkley 5 days ago [-]
No it’s totally that thing you said at that party when you were drunk. Seriously, how could you?
shagie 5 days ago [-]
The rocket equation makes this number fairly calculable.

One doesn't have to go too much larger before it is impractical to get off the planet with even the best theoretical chemical rockets.

floxy 4 days ago [-]
Maybe you don't carry your own fuel?

...not saying this is directly applicable, but maybe food for thought?

shagie 4 days ago [-]
That's interstellar - which is a different set of problems. The main one is getting out of the gravity well of the planet.

On a super earth, such as Kepler 20b ( ) in order to lift 1 ton of mass to orbit, it would need 9000 tons of fuel -- about 3x larger than the Saturn V. To get the JWST off the planet, it would take 55,000t of fuel. To get that 45t of an Apollo mission off the planet, it would take about 400,000t of fuel over 100x more than the fuel needed for Saturn V.

elevaet 5 days ago [-]
So conversely the best candidate for a space-faring species might be from a very small planet.
Ekaros 5 days ago [-]
Probably something between Earth and size of Mars. As getting too light makes holding atmosphere harder.
lampshades 4 days ago [-]
Kind of like how the best candidates for original sea travel came from small islands.
koheripbal 4 days ago [-]
No, because smaller planets cannot hold an O2/CO2/N2 atmosphere like ours.
elevaet 2 days ago [-]
There must be a sweet spot size of planet that is less massive than ours, but that is still big enough to hold an atmosphere.

edit: "That critical size, according to Arnscheidt and the other authors of the study, is 2.7 percent the mass of Earth. They say that any smaller than that, and the planet simply won’t be able to hold onto its atmosphere and water long enough for life to appear."

So, a mercury sized planet could hold an atmosphere in theory, and require around 1/3 the velocity to escape (vs. earth)

shagie 1 days ago [-]
The tangent to this is - the reason that Mars doesn't have much of an atmosphere isn't that its not gravitationally massive enough to hold on to it, but rather that its core cooled and lost its magnetic shielding. The lack of a magnetosphere then allowed the solar wind to strip its atmosphere.

rejor121 5 days ago [-]
Imagine how strong they are coMpared to us.

Want to be a gym bro, or do you want to just visit a super earth for a couple years?

wruza 4 days ago [-]
Higher gravitation is not only a muscular stress, I believe our internal organs and vessels will suffer or fail relatively quickly because there is not enough growth/strength adaptation designed into them. You’ll be not happy about your digestive tract alone weighing few kilograms more just by default.
AlgorithmicTime 4 days ago [-]
midoridensha 5 days ago [-]
A larger planet doesn't necessarily equal higher gravity at the surface.
bee_rider 4 days ago [-]
The gravitational acceleration at the surface is proportional to M/r^2 (where M is the mass and r is radius), and the mass should be proportional to r^3 assuming (big assumption here, but still) the density is constant.

IMO, it is pretty notable that the acceleration at the surface is only linearly proportional the the radius for a constant density, I'd expect something much worse.

Of course we can play with the density but chemistry is, like, way harder than physics.

dreamcompiler 4 days ago [-]
Sure. An extremely advanced civilization could hollow it out and make a "Dyson planet" -- or just build a shell from scratch -- but it ain't gonna form through natural processes.

I suppose somewhere in the universe there could be a dust cloud of pure lithium that eventually coalesces into a planet, but that seems extremely unlikely. (Interesting premise for a SF story though.)

midoridensha 2 days ago [-]
>An extremely advanced civilization could hollow it out and make a "Dyson planet" -- or just build a shell from scratch

Wouldn't this be impossible because of the planet's molten core? Or am I just biased because our planet has a molten core and I'm assuming it's necessary for a life-bearing planet, or at least unavoidable for any planet where its host star hasn't burned out from old age?

Finally, even if you could remove the molten (or solid) core of a planet, wouldn't the shell collapse due to gravity and other forces?

It seems to me that all these planetary engineering ideas really don't make that much sense. If you have such advanced technology that you can do these things, wouldn't it be faster and easier to build an O'neill cylinder and get exactly the environmental conditions you desire?

dreamcompiler 1 days ago [-]
I can't really imagine how hollowing out a planet could work, but I suppose if you figured out a way to do it you could replace the iron core with superheated water or something similarly less dense than iron. That's why I also suggested just building a shell from scratch. It would effectively be a very tiny Dyson sphere.
taskforcegemini 5 days ago [-]
maybe not necessarily, but anything else is probably not very likely
njarboe 5 days ago [-]
Why would you be trapped? The fact that you would need to build a nuclear rocket to escape might actually speed up space exploration on such a planet.
dhbradshaw 5 days ago [-]
This is exciting, but I think I'm most excited about learning to make self-sufficient and self-replicating colonies in space.

If we focus on settling planets, then each planet is its own set of problems.

But if we focus on learning to live in space, then although it may be harder initially, it's a single problem to solve. Then we just keep working and improving on that solution. And there's a lot more space out there than there are habitable planets. And there's a lot more matter and energy out there than are available on those planets.

bee_rider 5 days ago [-]
I don't really understand the idea of colonizing a planet.

If it is going to be totally independent of Earth, you'll have to set up the entire industrial base and population of that planet.

If it is going to be economically linked to Earth, then we're going to have to deal with shipping stuff there. And, like, what will they sell to Earth? I guess it would have to be really valuable and specific to that planet, to justify manufacturing it there and then lifting it out of a massive gravity well.

Space colonies at least have the hypothetical benefit of zero-g industry, aren't downwell, and can move around. Space colonies in the asteroid belt are the way to go, IMO.

TheOtherHobbes 4 days ago [-]
Too many people believe you can colonise planets with the modern equivalent of a horse and covered wagon.

You can't. It's much, much harder than that.

Getting to any kind of self-sufficiency anywhere is going to be incredibly difficult. You literally have to invent a complete industrial production chain for materials, machinery, and food and air that operates in a completely different and much more hostile physical environment with a completely different mix of available raw materials, much less solar energy, and no initial biosphere.

koheripbal 4 days ago [-]
You added a bunch of constraints there which equate it to colonizing an uninhabitable planet like Mars.
bee_rider 4 days ago [-]
If you are picking from inside our solar system, you are pretty much limited to Venus or somewhere that gets less solar radiation than Earth. Apparently the clouds of Venus are relatively habitable (in the sense that they aren't the hellscape of the surface of that planet, or the nearly oxygen free wasteland that is Mars).

Colonizing planets outside the solar system seems to require some sort of sci-fi technology just to get there, so it is hard to speculate. If we're going to assume we can somehow get to Alpha Centauri, we might as well also assume that when we get there we can use nanobot magic or whatever to transform the colonists into an alternative form that is compatible with whatever environment we find there.

koheripbal 3 days ago [-]
> If you are picking from inside our solar system

That, again, is a pretty big new constraint you are placing to make an argument.

Since we're talking about exo-planets, that's not a reasonable constraint in this conversation.

> Colonizing planets outside the solar system seems to require some sort of sci-fi technology

Yes - yet that's the context of this thread.

bee_rider 2 days ago [-]
The article was about the search for life, so clearly we're off on a tangent here if we are talking about space colonization. I guess I assumed it was about semi-realistic space colonization, because the comment that kicked it off talked about the solving problems -- if we have magical sci-fi technology there's no reason to talk about this, because we have no way to speculate which problems will have an automatic sci-fi answer.

Anyway, if you pick apart the problems described in the first post you responded to, you'll find, I think, that the only restriction imposed by limiting the discussion to planets inside the solar system is the "less solar energy."

Ekaros 5 days ago [-]
Always thinking of the making all the stuff. And I mean literally all the stuff, everything needed during life. In probably more hostile environment than we live. Probably would get old rather fast...
dylan604 5 days ago [-]
>then each planet is its own set of problems

yes, but we already know how to solve these problems. living in an atmosphere on terra firma with resources is something we can do.

>although it may be harder initially, it's a single problem to solve

hmm, and as of now these are unobtainable solutions: unlimited power source, radiation shielding, etc. so unless one of these planets has a more advanced race that can share how to get over these little hurdles, this plan is just sci-fi

nawgz 5 days ago [-]
Interesting idea.

To me, exoplanet surveys are one of the most exciting forms of science. I can think of no other thing that would bring us closer to understanding whether or not life does exist in our universe beyond us.

I've long held that it does, but it feels to me that belief is practically religious, completely unfounded. Combined with the fact that I think no other event will impact our world for the better more than knowing this universe has other life... I have my fingers crossed for the giant ground-based teles they listed at the end. Godspeed

denton-scratch 5 days ago [-]
> one of the most exciting forms of science.

Not to me, I'm afraid. Suppose we detect CO2, methane and ammonia in the atmosphere of some exoplanet tens of lightyears away. Hell, suppose we detect definite evidence of life. What difference is that going to make to anything? We couldn't launch a probe that could get there in a lifetime, going at half the speed of light. We certainly couldn't get the probe back again. You'd need a generation ship to get people there.

I'm quite sure there's life out there. I'm also fairly sure that very little of the life out there is organised for (or interested in) interstellar travel; and for most destinations, that life would have evolved by the time of arrival, and the space-traveller would be something that can only live in space. A civilisation that can build a rocket has existed on Earth for only a few decades, and might only last a few decades longer.

We could certainly send a probe to Proxima Centauri. Our great-grandchildren could record the results, if they'd spent two lifetimes keeping the probe in contact and under control (fairly boring astronomy career: maintain contact with a spaceship that was launched before you were born, and won't arrive before your grandchildren have died).

floxy 4 days ago [-]
throwaway743 5 days ago [-]
I'm gonna get downvoted to hell, but watch the doc, The Phenomenon. It's pretty damn convincing.

As you said, yeah it's a leap of faith without (at least publicly available) empirical evidence, but who cares. It's fun thinking about the possibilities of others out there, interacting, and sharing with them. Even better if they share their tech so we can travel distances off and away from this crumbling rock.

In any case, I believe we've already been contacted, at least since nuke testing, and that the US andnother govs have recovered craft that are handled by contractors. Watch the doc. It's not woo woo crap. I mean Harry Reid is in it and he implies a lot to say thr least.

Here's a link, just use uBlock to get rid of the ads

sammalloy 5 days ago [-]
I’m familiar with the so-called evidence you’re discussing. The thing is, there’s no reputable, authoritative source that will go on record right now saying we are positively being visited by aliens. Nobody seems to know exactly what the phenomenon is, if it really does exist. More to the point, the notion of aliens themselves could very well be a culture-bound idea, just like angels and demons and fairies and spirits. We just don’t know. It could very well turn out to be propaganda and disinformation that hides something else entirely.
hedora 5 days ago [-]
It's interesting that planets could roam between solar systems for 10's of billions of years before becoming uninhabitable, and that such planets are likely common.
lumenwrites 5 days ago [-]
This would be such an amazing premise for a scifi movie. One such planet drifts through the solar system, and we have like 3-5 years to make contact with whatever lives there before it drifts away.
jabbany 5 days ago [-]
There kind of is already:

The premise is that humans turned the Earth into a planet-scale space vessel to escape the sun's expansion and rehome into a different solar system. Basically involved de-orbiting the Earth and coming up with a way to fling it out of the solar system whatnot.

The sci-fi parts are quite interesting, though I'd recommend the book instead of the movie (which is really a mediocre Chinese take on the Hollywood blockbuster...)

teh_klev 5 days ago [-]
> which is really a mediocre Chinese take on the Hollywood blockbuster.

I quite enjoyed the film. It was interesting to see a different cultural take on how to solve "future problems" in a different cultural SciFi. Would I watch it again? Probably not, was it any worse than the stream of MCU junk? Not really.

jabbany 5 days ago [-]
> was it any worse than the stream of MCU junk? Not really.

Exactly. Hence the "mediocre". It's a familiar storytelling format with a different set of ideological undertones. Nothing special but also not like it's bad or anything.

OTOH, Liu Cixin writes what I would call pretty good sci-fi novels and shorts which the movie doesn't do enough justice to. Then again that's more or less most sci-fi movies compared to their original works.

bolasanibk 5 days ago [-]
Shorter time scale but - Rendezvous with Rama by Arthur C Clarke
Something1234 5 days ago [-]
There was extraterrestrial life in that one, or am I thinking of hammer of god?
njarboe 5 days ago [-]
They can't. That sentence in the article is wrong according to the paper it references to support the statement. See [1].


awb 5 days ago [-]
> By definition, super-Earths have many of the attributes of a super habitable planet.

Is that true?

> A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively.[1] The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability.

uup 5 days ago [-]
That's mentioned in the article:

> A super-Earth is any rocky planet that is bigger than Earth and smaller than Neptune.

If you read further in the article, it explains why super-Earths are a good target to look at for extraterrestrial life.

awb 5 days ago [-]
But the “by definition” part seems incorrect. Nothing in the definition of “Super Earth” indicates superior habitability.
shagmin 4 days ago [-]
It may not be worded well but it does state why. Planets of this size are more likely to be geologically active, a sufficient size to retain an atmosphere thick enough for life, a strong enough magnetic field, etc.,. Just due to their size, they are better suited to support life then (at least as we know the conditions necessary). I mean between the other options - planets so small they're basically rocks in space and giant gas planets with a bunch of other issues - it seems this classification of planets indeed offer superior habitability.
uup 4 days ago [-]
The author goes on to explain why super earths are a good place to look for habitable planets. It’s the entire point of the article. Planets meeting this definition also tend to have other characteristics as well.
rbanffy 5 days ago [-]
Super Earths are easy to find and super common but I am almost betting the most life will be found in gas giant moons. Even though we don’t have any gas giants in our own system that have Earth-sized rocky moons, each one of ours has half a dozen “almost-there” moons. A civilisation developing around a gas giant with multiple habitable and easily accessible moons would be very interesting.
zeroth32 5 days ago [-]
Magnetosphere of planet like Jupiter or Saturn is the most radioactive place in solar system... Also energies (delta V) needed to travel between Jupiter moons are greater, than those needed for travel between solar planets.
rbanffy 4 days ago [-]
> Magnetosphere of planet like Jupiter or Saturn

I thought Saturn was mostly benign. My hope was that a magnetosphere would protect the moons from the early outbursts of the red dwarf.

> Also energies (delta V) needed to travel between Jupiter moons

That's surprising. Found this nice map [1] and the numbers are really disappointing. ~15 kps from Titan-to-Iapetus sucks (even though it's ~4 kps less than Earth-to-Mars). At least the distances are smaller...

jjoe 4 days ago [-]
> While there are many reasons why a habitable world would not have signs of life, if, over the coming years, astronomers look at these super habitable super-Earths and find nothing, humanity may be forced to conclude that the universe is a lonely place.

Interesting... The "no" is definitely cheaper and faster than the "maybe" or "yes." If we get a "no", what's next? Planet-wide depression?

api 4 days ago [-]
Yes means there is life out there. No means there isn't life in the specific place we looked, but the universe is very big. So no is really pretty meaningless.
thathndude 4 days ago [-]
No has to be understood to be “maybe.” if there’s one negative that will be very very hard to ever approve, this is it.
philsnow 5 days ago [-]
> So the most habitable planet would have roughly twice the mass of Earth and be between 20 to 30 percent larger by volume.

So, ~60% denser than Earth? Density is mass/volume, and 2x / 1.25x = 1.6x.

The math works out really well if they meant a 20-30% larger radius: 1.25*3 = 1.95, so similar density but larger volume.

sidcool 5 days ago [-]
Wouldn't it be physically impossible to escape the gravity of a super Earth using the currently available and known propulsion technology we have here on Earth?
jccooper 5 days ago [-]
Not quite, but as mass increases relative to Earth, launch vehicles become increasingly ridiculous. Many "super-Earth"s would need something like a Saturn V to get to their equivalent of the ISS, or maybe even their equivalent of Sputnik, depending on exactly how "super".

When you start to get into gas giant mass, chemical launch starts to become really close to impossible instead of just wildly unaffordable.

hinkley 5 days ago [-]
We haven’t even come up with a material strong enough to build a space elevator here on earth. On a heavy planet you need an even higher strength to weight ratio.

Your space platform would practically have to be a floating city, since mountains won’t even be as high.

29athrowaway 5 days ago [-]
If they're bigger then they have more mass and therefore a higher gravitational pull, which makes every task more expensive.
teh_klev 5 days ago [-]
We don't have to live there. If there is a sentient industrial space faring equivalent of our species then trade, cultural exchanges etc can be performed off-planet. There are ways around these problems.
Qem 3 days ago [-]
Natural selection would just favour smaller body sizes. Ants can lift tens of times their own weight. The question is, what's the minimum body mass that would still allow human-like intelligence?
Chris2048 4 days ago [-]
Depends on the density, and the distance from the surface to the centre.
fsiefken 4 days ago [-]
so we probably are not alone. the next questions for me are: how rare is first "one-way" contact between intelligences? and how rare is asynchronous two-way contact (centuries or milllenia in between messages) and how rare is two way immediate contact in our galaxy?
graycat 5 days ago [-]
Apparently there is high interest in finding life elsewhere in our galaxy, or in other galaxies.

Since a lot of such interest is resulting in US federal government funding and I am a US citizen, I have standing, if only as a taxpayer, in this interest.

About this interest and paying to pursue it with my tax money, I ask "Why should I?".

I confess that getting good evidence of such life would be curious, entertaining, fun, etc.

For any in doubt, I will just stipulate that there is a lot of life out there in our galaxy and the rest of the galaxies in the universe. Done. No more wondering or arguing. If you want, I'll also stipulate that they are all little, green, and have 10 legs and 5 eyes. And I will agree that we might find evidence of a Dyson sphere (build a sphere around a sun and collect all or a lot of the energy it radiates).

Second, but I will insist that, from all we know about physics now, there is no way for us ever to have anything like practical two way communications with any life that evolved outside of our solar system.

Third, with current physics, the search for life is at best just curious, entertaining, fun, etc., and, sorry, on these criteria some good movies are better! I can buy a good movie on a DVD for about $10 -- so if I give $10 for the search for that life, I'm all paid up?

Fourth, really, then, the search for such life needs to include a search for some radical new physics. If want to pursue promising research directions in such physics, okay by me, but such research efforts should be low budget unless very promising, and I doubt that there will be any promising directions.

So, net, whatever astronomy, astrophysics, etc. are good for, the search for life that evolved outside of our solar system is not very serious -- or, such life IS there but with current physics there are no significant consequences for us. Sorry 'bout that.

Or, a big effort on the search for such life looks to me like some researchers want to do a big selling job to get taxpayers to give them an interesting career. Sorry 'bout that.

Or, if the search for life is mostly just for a search for some radical new physics, then sell the effort as a search for the physics, not the life. Or I agree already that there is a lot of life out there, but with our current physics there are no consequences for us -- stipulate that they are all green with 5 eyes and get no conflicting data.

genericone 5 days ago [-]
The alternative: make billions selling ads so you can finally sell the company to really focus on your passion of spending billions on developing tech and lobbying for policy towards searching the cosmos for life.
graycat 5 days ago [-]
All fine except for the goal of searching for the life. Or as I tried to make clear, first have to find some radical, new physics. If I make the $billions, glad to fund that.
anentropic 5 days ago [-]
What does "more habitable than earth" even mean? Habitable to whom?
every 5 days ago [-]
We didn't evolve there so we most likely couldn't survive there. And these planets are so distant we will almost certainly never visit there. Essentially nothing more than entertaining pipe dreams...
jrvarela56 5 days ago [-]
Oh we will, just not in these meat suits.
tgv 4 days ago [-]
The chances of mass extinction are a tad higher than those of use uploading to some non-corporeal construct and travelling at lightspeed.
jrvarela56 4 days ago [-]
We can do the upload first and figure out lightspeed travel while in there.

Chances of figuring out the upload before we do the extinction are higher imo. This whole AI boom may make it happen sooner than we think. It won't be the upload we all expect ("Am I me in there?") but it'll have human-like thoughts and consume the data we've produced so it'll be us/human in as fluffy a way as we define consciousness right now.

tgv 4 days ago [-]
I don't think there will ever be an upload. That "AI boom" is nothing more than the capability to train very large networks, and (that's indeed a first) a recurrent one. But it doesn't resemble our way of being and thinking.

But your variation makes it pertinently clear that it's not "us" who's going to visit those planets, but something else entirely. And why would we need a "super habitable" planet if we're just electrons in a few chips, anyway (ignoring the fact that electronics tends to die in 20 to 30 years of use, but hey)?

JadeNB 5 days ago [-]
The actual title "Super-Earths Are Bigger and More Habitable Than Earth, and Astronomers Are Discovering More of the Billions They Think Are Out There" is doubtless too long for HN, but the mangler truncated it at the "Di" of "Discovering", which is surely suboptimal.
dang 4 days ago [-]
Yes, and also somewhat baity. We've replaced the title with a representative phrase from the article body.
mrtri 4 days ago [-]