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Earth-like planet spotted orbiting Sun’s closest star

nature.com

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Re: Earth-like planet spotted orbiting Sun’s closest star

#51

Post by rbanffy »

denton-scratch wrote: post #16

"Earth-like planet"? It orbits the star every 5 days; it's a quarter of the earth's mass. It's also a tenth the distance from its star that Mercury is from the Sun. It's earth-like only in that its temperature is consistent with there being liquid water.

IIRC from other publications, they expect something between .26 and 1.1 Earth masses, so it may well be a reasonably big rock. Surface gravity, composition and atmosphere are also big factors in being Earth like - Titan has a lower gravity, but a much thicker atmosphere than Earth.

Re: Earth-like planet spotted orbiting Sun’s closest star

#52

Post by rbanffy »

mortehu wrote: post #40
denton-scratch wrote: post #16

"Earth-like planet"? It orbits the star every 5 days; it's a quarter of the earth's mass. It's also a tenth the distance from its star that Mercury is from the Sun. It's earth-like only in that its temperature is consistent with there being liquid water.

"Earth-like" just means terrestrial, as opposed to jovian. It means it has a rocky surface.

Venus is also classified as Earth like, but it's rocky surface looks more like hell than the mythological descriptions of it. ;-)

Re: Earth-like planet spotted orbiting Sun’s closest star

#53

Post by rbanffy »

grishka wrote: post #50
rbanffy wrote: post #44

Earlier quoted context omitted.

Even if you get a very high specific impulse, you still need to pack a lot of reaction mass. You'll also need a lot of supplies (or a biome) because even if you get to 0.1 c, it's still 40 years to get there.

I'm not losing hope that there are ways to travel faster than the speed of light that we haven't yet discovered, like bending the spacetime around the spacecraft, or wormholes, or something else of that kind. If various forms of rapidly ejecting matter out of a nozzle really are the only physically viable option for spaceflight, it would be an extremely disappointing universe.

> If various forms of rapidly ejecting matter out of a nozzle really are the only physically viable option for spaceflight, it would be an extremely disappointing universe.

Indeed. If that's the case, the universe is an infinitely big and infinitely boring place.

OTOH, our future uploaded selves may be able to slow down their clock rates and make the trip so much shorter.

And you don't need to leave your dear ones on Earth - just bring forks of them along you (chances are a fork of you will remain on Earth anyway).

Re: Earth-like planet spotted orbiting Sun’s closest star

#54

Post by parksy »

udbhavs wrote: post #12
parksy wrote: post #4

Sweet let's crank up the generation ships. Of course picking a suitably inspiring name should be the first priority. Unity? Terra Nova? Gaia? On a more serious note is this a good candidate for JWST, would it be able to infer chemical composition from the planet's spectrum or something? Awesome though we went from (in my lifetime) learning at school that other planets have never been observed, to finding them sprinkl…

Unrelated but I keep reading that abbreviation as Json Web Space Token

Now the seed is planted, one of us is going to talk about JSON Webb Telescopes in a development meeting.

Re: Earth-like planet spotted orbiting Sun’s closest star

#55

Post by _blu »

NeoTar wrote: post #15

Another point for anyone considering whether we should send a space-probe there... The current fastest man-man object is the Helios 2 space-probe, reaching something like 25 000 kilometres per hour. Proxima Centauri is 1.3020 parsecs away from Earth. So, just diving one by the other, we'd looking at something like 18 000 years as a rough order of magnitude for sending something from Earth to Proxima Centauri. You'd b…

we need to send out a probe now before it's too late

Re: Earth-like planet spotted orbiting Sun’s closest star

#56

Post by T-A »

There seems to be some confusion about the meaning of "within the habitable zone".

From the paper (Introduction and Conclusions, respectively) [1]:

The habitability conditions of Proxima b, which orbits within the HZ of the star, have been extensively studied (e.g. Barnes et al. 2017; Ribas et al. 2016; Turbet et al. 2016; Meadows & Barnes 2018). On the other hand, the candidate Proxima d orbits much closer to the star and outside the HZ range.

In particular, the discovery of an Earth-mass planet orbiting Proxima Centauri (Anglada-Escudé et al. 2016), our closest stellar neighbour, was one of the most significant results in the field, in part because the planet orbits inside the habitable zone (HZ) of the star (e.g. Kopparapu et al. 2013).

So, Proxima d is too close to the star to be inside the HZ; it's within the HZ in the sense that the HZ is further out from the star.

The author of the Nature commentary, which claims that "it could have oceans of liquid water that can potentially harbour life", apparently didn't read the paper.

[1] https://www.eso.org/public/archives/releases/sciencepapers/e...

Re: Earth-like planet spotted orbiting Sun’s closest star

#57

Post by enkrs »

b3lvedere wrote: post #5

"The team used a state-of-the art spectrograph called ESPRESSO" And suddenly i am imagining lots of very smart people drinking lots of caffeine. "To find the wobble.." this is not helping :) "ESPRESSO is kept in a special room at the observatory, inside a tank " oh come on ..

Astronomers go to great lengths to name their stuff for good abbreviations. ESPRESSO is actually “Echelle Spectrograph for Rocky Exoplanet- and Stable Spectroscopic Observations”

Re: Earth-like planet spotted orbiting Sun’s closest star

#58

Post by lbriner »

WithinReason wrote: post #20
lbriner wrote: post #17

We can't even work out how to run our own planet in a consistent and consensual way, I say leave it to the other more civil aliens to inhabit, otherwise we'll end up with another broken planet.

What is there to break on a lifeless planet?

Clearly the implication is that it is another habitable planet and the other comments talking about going there etc. It isn't the rock I am worried about, it would be community that decides to move there and then starts exploiting each other leaving a planet depleted of resources and a rather long journey home!

Re: Earth-like planet spotted orbiting Sun’s closest star

#59

Post by messe »

Udo wrote: post #21
NeoTar wrote: post #15

Another point for anyone considering whether we should send a space-probe there... The current fastest man-man object is the Helios 2 space-probe, reaching something like 25 000 kilometres per hour. Proxima Centauri is 1.3020 parsecs away from Earth. So, just diving one by the other, we'd looking at something like 18 000 years as a rough order of magnitude for sending something from Earth to Proxima Centauri. You'd b…

I find it enjoyable to think about the technologies that might just be in the cards further into the future. If we ever figure out light-weight fusion drives, we could build light hugger space ships that accelerate to a decent fraction of the speed of light. At 1g acceleration it takes about one year to get to 0.9c, which would make the Proxima system accessible with a travel time of about 6 years. Or 8 years at 0.5g…

> If we ever figure out light-weight fusion drives, we could build light hugger space ships that accelerate to a decent fraction of the speed of light. At 1g acceleration it takes about one year to get to 0.9c, which would make the Proxima system accessible with a travel time of about 6 years. Or 8 years at 0.5g. Or 9 years if we 'only' get to 0.5c.

No, we couldn't. The energy density of fusion isn't anywhere near close enough to make a lighthugger, you'd need insane mass ratios[1] and ramjets are probably unfeasible (as in, even-if-your-a-Kardeshev-II-civilization-unfeasible[2]).

[1]: http://www.projectrho.com/public_html/rocket/slowerlight3.ph...

[2]: https://www.sciencedirect.com/science/article/pii/S009457652...

Re: Earth-like planet spotted orbiting Sun’s closest star

#60

Post by semi-extrinsic »

uwuemu wrote: post #33
NeoTar wrote: post #15

Another point for anyone considering whether we should send a space-probe there... The current fastest man-man object is the Helios 2 space-probe, reaching something like 25 000 kilometres per hour. Proxima Centauri is 1.3020 parsecs away from Earth. So, just diving one by the other, we'd looking at something like 18 000 years as a rough order of magnitude for sending something from Earth to Proxima Centauri. You'd b…

A probe based on nuclear pulse propulsion could do it in around 50 years, with today's technology. It's not that we can't do it fast (within one average human lifespan), it's that the project would be very expensive and something like Nasa has a relatively tight budget. I mean we, as humanity, have to have an eccentric billionaire start a Martian fire (SpaceX Starship) under our lazy asses to even start to think abou…

Maybe an unpopular opinion, but Musk is just plain wrong when he thinks there is any urgency to Mars exploration (or it's just vicarious arguments because rockets are cool).

Basically, the tech you need to make a Mars colony truly self sufficient is something like a compact fusion powerplant.

Before we have that, no point in worrying about using Mars as a "backup plan", because if Earth was screwed, Mars would have a couple of years to live at most.

And obviously it would be vastly better for humanity if Musk spent money on zero-emission large scale energy production, than on rockets.

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