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Seven earth-sized planets discovered circling a star 39 light years from Earth

nature.com

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Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#681

Post by pharke »

jerf wrote: post #167
noobermin wrote: post #88

Earlier quoted context omitted.

Of course, #askNasa didn't win me a question, but could any astrobiologists comment on this question: Tidal locking means the planets would always have a side facing the star, leading to very different thermodynamics in terms of climate and weather on the planet, not to mention radiation. Doesn't that very much hurt the chances for life on those planets?

The debate rages. The problem is that one side of the planet is essentially exposed to space and thus tends to be at cosmic background temperature, and the other side exposed to the star. It is thought by a lot of people that anything volatile enough to be a gas, ever (so, including water), would rapidly end up migrating over to the frozen side, so even if the planet started with the right mix of water and whatever o…

What about tidal and geological heating? or a greenhouse effect similar to Venus?

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#682

Post by shawn-furyan »

kybernetikos wrote: post #610
shawn-furyan wrote: post #513

Earlier quoted context omitted.

Corrections aside, it is an interesting observation that Firefly is less outlandish with this discovery (not a criticism, Firefly is optimized for fun, not scientific plausibility). Still, assuming light speed travel, Firefly's inhabited planets are still a heck of a lot closer, since the crew doesn't seem to noticeably age between the half dozen or so star systems that they visit, and don't appear to have any kind o…

> assuming light speed travel, Firefly's inhabited planets are still a heck of a lot closer, since the crew doesn't seem to noticeably age between the half dozen or so star systems If you travel at light speed from your own point of view you arrive instantly due to time dilation, so even if it takes years according to an outside observer (because the distance you're travelling is light years) you wouldn't age at all.…

Ah, yes. Forgot all about time dilation effects. In my defense, it was a pretty off the cuff response. Also, I would assume they aren't meant to be literally traveling at exactly light speed, but I don't know the relevant equations to figure out how that impacts my comment. Clearly, in this area, I'm a dilettante at best.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#683

Post by dTal »

dcposch wrote: post #496
dmix wrote: post #6

My favourite part of the press release: > The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth's sky. > In contrast to our sun, the TRAPPIST-1 star – classified as an ultra-cool dwarf – is so cool that liquid water cou…

> The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth's sky. this reminds me of one my favorite films ever. it is just four minutes long http://www.erikwernquist.com/wanderers/

Wanderers is indeed excellent.

See also: the timelapse footage of the sky from the VLT, Paranal. Just thinking about it gives me vertigo.

https://www.youtube.com/watch?v=wFpeM3fxJoQ

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#684

Post by jerf »

pharke wrote: post #681
jerf wrote: post #167

Earlier quoted context omitted.

The debate rages. The problem is that one side of the planet is essentially exposed to space and thus tends to be at cosmic background temperature, and the other side exposed to the star. It is thought by a lot of people that anything volatile enough to be a gas, ever (so, including water), would rapidly end up migrating over to the frozen side, so even if the planet started with the right mix of water and whatever o…

What about tidal and geological heating? or a greenhouse effect similar to Venus?

Any heat source exposed to space has the basic problem of its volatiles running away and not coming back. On geological time frames, this effect is probably nearly instant, so it isn't very helpful that maybe a new volcano could pop up somewhere and melt lots of stuff or something, because all that does is put a hole in the permanently frozen layer. Any heat source not exposed to space might harbor life, but that's not particularly true of these planets; we already have things like Europa locally with the same possibility.

The issues with valuable resources running away and not coming back is a serious one even for Earth, which I think might surprise some people. The geological carbon cycle [1] in particular is one that may surprise people who have not encountered it before, or not thought about it in terms of extraterrestrial life. On geological time scales it's surprisingly easy for entire important elements to go find themselves a low-energy configuration they like and disappear from any putative biosphere. The issues with a tidally-locked planet providing such solutions to "all gasses liquids" is merely an extreme example of the case, and really makes one wonder how it would be possible for such a planet to stay "stirred" enough for life to have access to what it needs to develop.

[1]: https://en.wikipedia.org/wiki/Carbon_cycle#Geological_carbon...

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#685

Post by dekhn »

sheeshkebab wrote: post #596
dekhn wrote: post #283

Earlier quoted context omitted.

Short answer: almost certainly yes, although i presume this is an improbable event.

According to some research, microbes survival in meteorites is very likely (if they exist) https://www.ncbi.nlm.nih.gov/m/pubmed/11543506/

I know enough biology to be skeptical of papers like that (although, I admit I was skeptical when papers from the 50s predicted interplanetary mass transport, and didn't change my mind until we found Martian meteorites). I'd like to see actual evidence of this.

I actually think the rock getting into space with the microbe embedded in it is not that unlikely (many rocks in the earth are laced with bacteria), nor the space transport. I think the excessive heat of rentry, the force of impact, and the difference in target ecosystems are what are going to kill the microbes.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#686

Post by drzaiusapelord »

ithkuil wrote: post #599
ashark wrote: post #477

Earlier quoted context omitted.

Plus climate change would have to get pretty incredibly bad for, say, Mars to start looking easier to live on than Earth. That's the problem with colonization as an Earth back-up—even Antarctica and the Sahara Desert are more livable than any other body in the Solar System, by a long shot. Another Snowball Earth or a heavily desertified Earth would still be preferable to Mars. Throw in a fair amount of radiation, eve…

But if you could go out now and terraform a planet so that when in future you have problems here you have a place to go to that matches the original environment back on earth. And you learn a lot of things about "geo"engineering, the things you cannot try safely at home, which can come in handy to fix any problem back on earth.

We have no ability to terraform anything, let alone a planet, let alone the economics of it ever being feasible. Life isn't a star trek episode. We can't just go and 'terraform now' as you say. We can barely land anything on Mars without a 50% failrate right now. We're talking technology way, way into the future. Hundreds, perhaps thousands, of years.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#687

Post by kakarot »

Retra wrote: post #598
kakarot wrote: post #581

Earlier quoted context omitted.

It seems the rest of HN disagrees with me, but when I hear "trillions" I think in plurality of trillions, a handful maybe, but afaik these things don't really live past 2 trillion years

That's because that number is a reference to a plurality of years, not a plurality of trillions.

If you say so, I guess I'm just wrong about this. Thank you for trying to clarify for me, instead of just downvoting me into oblivion like everyone else.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#688

Post by logfromblammo »

stagbeetle wrote: post #397
logfromblammo wrote: post #182

Earlier quoted context omitted.

If pixie dust is plutonium and unicorn farts are tetradeuterium-methane, you could get there in 400 years or so, Earth-time, 398 years shipboard time. So you really need your pixie dust to be antimatter, and your unicorn farts to be terawatt lasers. For now, the wait calculation suggests that anyone leaving now will reach their destination after someone who waits to leave until after the next breakthrough in space pr…

I see "antimatter" and "black hole" being thrown around as a source of propulsion in this thread. Is this based on anything real like using the energy created from the radiation or just sci-fi speculation?

Positrons cost $25M/mg and antihydrogen costs $62.5B/mg.

An interstellar trip to Alpha Centauri using antihydrogen-hydrogen annihilation reactions would cost more than 50 years of the entire economic output of the planet (as of 2016) just for the fuel. Since we need a large portion of that economic output for basic survival needs, there will be no antimatter rockets built any time soon.

As far as I am aware, we currently lack the capability to create a singularity massive enough to persist long enough to observe as a black hole. But it is possible that we might be able to locate a primordial black hole near enough to build a propulsion system around it, or even trap one as it passes through Earth. This would, of course, require that primordial black holes exist, and that they emit Hawking radiation.

Yes, for now it is purely speculation. Anything beyond chemical-energy rockets is speculation until we actually demo the technology in a real spacecraft. If you launched today, bound for Alpha Centauri, the best you could do is drop fusion bombs behind your vessel until you get to about 0.08c, turn around at some point and throw fusion bombs in your path to decelerate, and be prepared to arrive a long, long time from now.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#689

Post by 0x6c6f6c »

mememachine wrote: post #660
echelon wrote: post #575

I imagine any intelligent life that evolves on a system with so many planets in such close proximity--many within the habitable zone, and each perhaps with atmospheres and organics--will have a much easier time than we do of pushing forward to becoming a multi-planetary species. We lucked out with Earth being as hospitable and resource rich as it is, but we're stuck in a deep gravity well with not much in our solar s…

> could have been You write like its all over. Pretty odd.

No, it's written like a thought on how we as a species would have evolved given the possibility of visiting a close planet instead of the moon at the same age of technology. I mean with closer proximity it would have been a race to a neighboring planet rather than touching down on the moon, and where we are now we could have feasibly accomplished interplanetary travel without issue already.

His comment doesn't even bring up our current situation, but would could have been if we had closer neighboring planets.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#690

Post by nicolewhite »

dcposch wrote: post #496
dmix wrote: post #6

My favourite part of the press release: > The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth's sky. > In contrast to our sun, the TRAPPIST-1 star – classified as an ultra-cool dwarf – is so cool that liquid water cou…

> The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth's sky. this reminds me of one my favorite films ever. it is just four minutes long http://www.erikwernquist.com/wanderers/

Reminds me of the movie Melancholia.
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