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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

#731

Post by Arizhel »

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…

>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

My understanding is that Firefly does not have FTL travel at all, in fact that makes it rather unique among spaceship sci-fi. Also, they're in a single (though very large with multiple stars) system. They get around quickly because their ships are a lot faster than our slow-ass chemical rockets, but they're still traveling at sublight speeds, which is why it takes days or weeks to get places, instead of mere minutes (for example, at lightspeed, it would take less than 6 hours to get to Pluto). Notice that, in the show, they took paying passengers, and it took a fair amount of time to get between the "outer worlds". It was a lot like cargo ships of yesteryear, rather than modern airplanes, as far as travel time. They don't have tech to halt their metabolisms for the same reason we don't: they haven't invented it yet.

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

#732

Post by Arizhel »

saalweachter wrote: post #582
mirimir wrote: post #521

Earlier quoted context omitted.

My first reaction was WTF? Then 0.27^3 = 0.0197 And then, only 60% as dense (no core) so 0.0119 :)

One of my scale numbers is, everything between Jupiter and the Sun masses less than 2 Earths -- Venus, Mars, Mercury, the Moon, and all the asteroids mass less than the Earth. And only just barely! You get to around 99% of the Earth's mass with the rest of the inner solar system. All of the other rocky bodies in the solar system give you another 10% of Earth's mass out to Pluto and another 10% beyond.

>One of my scale numbers is, everything between Jupiter and the Sun masses less than 2 Earths -- Venus, Mars, Mercury, the Moon, and all the asteroids mass less than the Earth.

Is that correct? Venus alone is about 90% the size of Earth, and Mars roughly 33%. It really seems like all those bodies put together should be greater than 1 Earth mass (but less than 2 Earth masses).

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

#733

Post by saalweachter »

Arizhel wrote: post #732
saalweachter wrote: post #582

Earlier quoted context omitted.

One of my scale numbers is, everything between Jupiter and the Sun masses less than 2 Earths -- Venus, Mars, Mercury, the Moon, and all the asteroids mass less than the Earth. And only just barely! You get to around 99% of the Earth's mass with the rest of the inner solar system. All of the other rocky bodies in the solar system give you another 10% of Earth's mass out to Pluto and another 10% beyond.

>One of my scale numbers is, everything between Jupiter and the Sun masses less than 2 Earths -- Venus, Mars, Mercury, the Moon, and all the asteroids mass less than the Earth. Is that correct? Venus alone is about 90% the size of Earth, and Mars roughly 33%. It really seems like all those bodies put together should be greater than 1 Earth mass (but less than 2 Earth masses).

That's size, not mass.

Venus is about 81% Earth's mass, and Mars is only a little over 10%. Mercury gets you another 5.5%, the Moon (as above) another 1.2%, and the asteroids are negligible.

In the outer solar system, it's basically all the Galilean Moons + Titan.

ETA: Hmm, or maybe those are surface gravity numbers you're thinking of?

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

#734

Post by BinaryIdiot »

nradov wrote: post #691
BinaryIdiot wrote: post #634

Earlier quoted context omitted.

Well today sending a rocket up, putting these things in orbit and then dropping them would probably be a bit obvious and inefficient. But in the near future when we're mining asteroids? As long as they can be captured closed enough to Earth I would imagine kinetic bombardment would be pretty effective. They would be rather difficult to shoot out of the sky as ballistic missiles can be blown up prior to reaching targe…

Asteroid mining on any sort of commercial scale is far future, not near future. Even with fully reusable rockets, asteroid mining wouldn't be profitable; anything we need can be obtained cheaper on Earth. Small asteroids are too irregularly shaped to be useful as precision-guided projectiles. As soon as they hit the atmosphere they're going to veer off course. Kinetic bombardment satellites — whether fully artificial…

> Asteroid mining on any sort of commercial scale is far future, not near future. Even with fully reusable rockets, asteroid mining wouldn't be profitable; anything we need can be obtained cheaper on Earth.

It's certainly in the future, it just all depends on what is far to you. Many companies who want to get in on this are hoping to attempt within the next 10-15 years (obviously commercial mining would come some years later after a successful attempt). If it can be successfully navigated it would have the potential to be crazy profitable!

It's too expensive to bring materials up but if you can mine materials in space and deliver them to the various space companies / government departments is where you'd make your money. Mining water, in theory, should be crazy cheaper as long as you can capture the asteroid efficiently enough. NASA has already said they would love to see more work in this space so they can purchase materials cheaper while in space and they're even hoping to capture an asteroid in the mid 2020s as a type of test for this scenario.

> Satellites are generally easier targets to hit than ballistic missiles.

This misses my entire point: in order to destroy the kinetic projectile you would have to launch a preemptive strike against the satellite. There is no way around it. You won't be able to defend yourself against a large projective being precision dropped onto your location without a lot of energy (so depending on what country you are maybe you can knock several into a few direction or vaporize with a high enough yield but you only get one chance at destroying it). Meanwhile a ballistic missile, while faster, can be destroyed with a hot enough laser.

I understand they're not practical and if you want to use an asteroid itself that's even more awkward. But when we start mining asteroids, in my opinion, it's going to become crazy practical and cheap.

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

#735

Post by throwanem »

kakarot wrote: post #580
throwanem wrote: post #212

Earlier quoted context omitted.

In which Firefox version?

51.0.1 32bit. Don't ask me why I'm running 32bit FF, this is news to me as well.

I'd be more inclined to ask why it worked for you in that exact version, but not for me in the very same one. (Mine might be 64-bit, but I can't see that making a difference here.)

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

#736

Post by nradov »

BinaryIdiot wrote: post #734
nradov wrote: post #691

Earlier quoted context omitted.

Asteroid mining on any sort of commercial scale is far future, not near future. Even with fully reusable rockets, asteroid mining wouldn't be profitable; anything we need can be obtained cheaper on Earth. Small asteroids are too irregularly shaped to be useful as precision-guided projectiles. As soon as they hit the atmosphere they're going to veer off course. Kinetic bombardment satellites — whether fully artificial…

> Asteroid mining on any sort of commercial scale is far future, not near future. Even with fully reusable rockets, asteroid mining wouldn't be profitable; anything we need can be obtained cheaper on Earth. It's certainly in the future, it just all depends on what is far to you. Many companies who want to get in on this are hoping to attempt within the next 10-15 years (obviously commercial mining would come some yea…

That's not how it would work. Incoming kinetic projectiles are just as vulnerable to defensive systems as ballistic missiles. Hit it hard enough and you can knock out the guidance system. They would need very precise and sensitive guidance systems to hit anything from orbit.

Space enthusiasts constantly underestimate costs and schedules. Just because something is theoretically possible doesn't mean that the engineering problems can be solved in an economical way. If there is large-scale asteroid mining in my lifetime then I'll eat my hat.

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

#737

Post by jimmaswell »

iamjeff wrote: post #724
jimmaswell wrote: post #558

Earlier quoted context omitted.

If you liked this, you'll probably also like MelodySheep's Symphony of Science series. https://www.youtube.com/watch?v=zSgiXGELjbc

This brought me to tears, literally... There is a beauty to the words that is hard to describe other than to say it gives "meaning" (for lack of a better word) to life on this rock.

Another good video is Sagan's "Pale Blue Dot" https://www.youtube.com/watch?v=4PN5JJDh78I&feature=youtu.be

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

#738

Post by callumprentice »

callumprentice wrote: post #607

A few months ago, I made a simple WebGL app to compare the sizes of our sun and the planets for my 5 year old daughter who was curious. I updated it today to include the TRAPPIST system and see how it compares to our own solar system. http://callumprentice.github.io/apps/celestial_bodies/index....

Thanks for the nice feedback everyone. I had some time tonight after work and made an improved version with better selection UI and allows for multiple bodies at once: http://callumprentice.github.io/apps/celestial_bodies/index....

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

#739

Post by 5xman »

TekMol wrote: post #269
5xman wrote: post #253

So, are there any plans to try to "communicate" with this planets? Or we are going to just sit and watch.

Well, we could send a message and then wait 80 years for a reply. So we might want to work on immortality first.

I thought we were already working on immortality. On the other hand, waiting 80 years doesn't seem like much. It's not like we are going to be 'out for lunch' if there is an answer.

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

#740

Post by jacobush »

nkrisc wrote: post #680
jacobush wrote: post #675

Earlier quoted context omitted.

"There is nothing inherently valuable about human life from a non-human perspective." How would you know?

It's a perfectly reasonable assumption until there's some evidence there is. Given the vastness and scale of the universe, it seems quite likely that our disappearance would never be noticed.

Going unnoticed is not the same as inherently not valuable. Imagine aliens finding us extinct, wringing their little tentacles in dispair at the lost probing opportunities. :)
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