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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

#571

Post by cgriswald »

shawn-furyan wrote: post #513
DougWebb wrote: post #272

Earlier quoted context omitted.

I always thought that Firefly's scenario of a bunch of Earth-like worlds in close enough proximity to have regular trading ships flying between them was unrealistic. Now, not so much. This system even fits in with the "Abandon Earth en-mass, move to new set of worlds" backstory. So, what did J.J. know, and when did he know it? And for that matter, how did he know?

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…

> 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

The 'systems' in Firefly are really all one star system. The system includes a central star orbited by planets, four other stars, and a host of "protostars" (they really mean brown dwarves). I've tried, and can't imagine a scenario where, even if such a system could form, that it could be configured in this way. The barycenter of the masses of this system can't possibly remain in the central star indefinitely, for starters. And the whole thing sounds hostile to planets - I imagine them being thrown out of the system constantly. But if you accept that, and you accept travel at some fraction of c, then you wouldn't expect them to age much like they would traveling between systems.

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

#572

Post by wallace_f »

Symmetry wrote: post #385
wallace_f wrote: post #260

Earlier quoted context omitted.

What determines my speed limit? Is it set at 0 here on earth? What if I travel to another galaxy, this one was going at .5c relative to me when I was on earth. Then after trillions of years, inflation causes all of the galaxies to separate beyond sight from me in this new galaxy. Now, the centre of this galaxy appears at rest. Does my velocity get "reset?"

Special relativity says that no matter what your velocity is relative to Earth you can proclaim that you're actually at rest and it's the other guy that's moving. So your velocity is always continuously being "reset". And in each of the frames of reference of everything in existence nothing else is traveling faster than the speed of light.

Assuming spacetime is not expanding, let's say 1 galaxy is moving away from us at .9c. I leave our galaxy and catch it by travelling at .99c. Then a citizen of that galaxy, at rest, accelerates to .9c. So his velocity relative to earth is .89c? I think I need to go watch a youtube video on special relativity. Intertial reference frames are really weird.

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

#573

Post by cgriswald »

andrewclunn wrote: post #224
mtgx wrote: post #35

Earlier quoted context omitted.

And they all seem to rotate around their sun in 1.5-20 days. https://i.kinja-img.com/gawker-media/image/upload/s--YG_G3T_...

Revolve around. Sorry, had to.

They're more-than-likely tidally locked, so... you're both right.

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

#574

Post by wallace_f »

OscarCunningham wrote: post #319
wallace_f wrote: post #63

Earlier quoted context omitted.

The answer for an outside observer is: @ 1g of acceleration it would take 11 months to accelerate to the speed of light. A formula you can put in Google is: (285000000/9.8)/(60x60x24). So 39-(.475x2) = 38, and 38/.95 = 40. So 42 years is your answer . I have no idea how to calculate the relativistic spaceship's elapsed time. It's all wishful thinking. The fastest thing man has created, the Juno spacecraft, travels, b…

This isn't how it works. As you approach the speed of light acceleration becomes less effective (i.e. you feel 1g but don't get faster at 10m/s^2). The interesting thing is that it's actually easier to calculate in the spaceship's reference frame. The two relativistic distortions cancel out and the Newtonian calculation gives the correct answer. So if you accelerate for the first half of your journey it takes you sqr…

>you feel 1g but don't get faster at 10m/s^2).

how does this work? it's consistent with what I've read about c requiring infinite energy, and I'm sure it has something to do with relativity, but I don't have an intuitive sense of it

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

#575

Post by echelon »

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 system to compel us to leave. That puts us at a relative disadvantage to other alien species that have the benefit of cheap and interesting neighbors to visit.

I'm jealous to dream of what could have been had we evolved in a differently configured solar system.

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

#576

Post by schoen »

blueprint wrote: post #559
schoen wrote: post #500

Earlier quoted context omitted.

Your posts here have been pretty disparaging toward the scientific community. The scientific community does have problems with groupthink and cognitive biases, but it also has to contend with a flood of people who passionately defend idiosyncratic ideas without appearing to appreciate what counts as a scientific theory or scientific evidence. Every scientist and other technical domain expert has encountered dozens or…

If I were attempting to propose a novel physical theory here, I would do exactly what you say. And in fact papers and apparatuses are being worked on. But here my point that we ought to establish another basket for our eggs stands entirely independently of the validity of such a theory/proposal. And what's interesting is how hard the push-back still is.

Space exploration and colonization have always been extraordinarily contentious issues, regardless of people's take on particular existential risks. I know people who think space colonization is unequivocally the most important thing humanity can possibly do, and people who think it's among the least important or maybe even actively wrongful. I don't think you can expect to find clear consensus on this point right now. But at least an Elon Musk-style "we should be working on permanent human presence in space to mitigate risks to humanity's survival" idea is relatively mainstream on HN.

Elsewhere in the thread you seemed to strongly disagree with other commenters about the expense of space travel, seemingly based on a technical proposal that you want to make, and you were dismayed about other people's reactions to your ideas. But in at least some views, the empirical questions about cost and feasibility must matter a lot, because space colonization doesn't mitigate every problem or risk humanity faces and might not appear as the only or best option for mitigating some of them right now.

Your technical ideas might cause you to weight some of these risks and costs very differently (for example, it sounds like you think human extinction on Earth is relatively likely soon and space travel can be made drastically cheaper than it is today), but that kind of disagreement puts you back in empirical-technical territory.

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

#578

Post by cgriswald »

cstejerean wrote: post #207
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?

Apparently what would hurt the chance of life in a tidally locked planet the most is that due to being tidally locked the planet would have a reduced magnetic field to protect the atmosphere, and therefore there is a good chance that the planet would lose it's atmosphere over time. https://en.wikipedia.org/wiki/Habitability_of_red_dwarf_syst...

Agreed, but there are other variables involved, including strength of stellar wind, density of atmosphere, whether a magnetic field is induced by the stellar wind, the mass of the planet (strength of its gravity), etc.

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

#579

Post by Sir_Cmpwn »

bcaulfield wrote: post #10
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…

So, basically, this is cooler than just about any world that's been depicted in sci-fi.

Sounds like you haven't read The Three Body Problem (which is a shame, you should totally check it out).
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