First atmosphere found on Earth-like planet in habitable zone of distant star • Hacker News Board

Re: First atmosphere found on Earth-like planet in habitable zone of distant star

#321

Post by cyberax » Sun, Jul 19, 2026, 6:58 AM UTC

DarmokJalad1701 wrote: post #320

hparadiz wrote: post #188

Earlier quoted context omitted.

We can do 7-8 AU per year right now using tech we have. Voy 1 and Voy 2 are moving at 3.59 and 3.25. A starship sized rocket could also possibly get a small payload that separates to 15 AU. This is all using conventual propellent. If you consider using nuclear explosive as a prepulsion technique the math starts to change substantially and you can achieve even 25 AU / year. https://ntrs.nasa.gov/api/citations/20140013…

Sure. But then how do you go from 7-8 AU/yr (33-38 km/s) to whatever the orbital speed is at that distance and also point that velocity vector in the correct direction for the orbit?

Technically, you don't need to stop. Gravitational lensing does not work like regular lenses, there is no "focal distance".

You have to be so far because that's the minimal distance where the Einstein ring becomes larger than the Sun's apparent diameter.

Re: First atmosphere found on Earth-like planet in habitable zone of distant star

#322

Post by palata » Sun, Jul 19, 2026, 12:24 PM UTC

bluGill wrote: post #317

palata wrote: post #312

Earlier quoted context omitted.

> Aren't the undiscovered ones just different colored insects or jellyfish? I was answering to someone saying that they would dream of seeing animals from another planet. Pretty sure that they (like everybody else) cannot list 0.01% of the insects out there. If one is interested in animals, there is more to discover on Earth than what they can realistically do in their whole life. Being interested in alien animals fe…

Problem is I'm not interested in insects. A new leader species of large mammal would interest me. Even discovering dinosaurs aren't extinct is neat but not something I'd care about.

It sounds to me like saying "I don't really care about football except the finals of the world cup. I wish we discovered alien football, that would interest me".

I get the point, but it sounds like you just don't care about football in the first place.

Re: First atmosphere found on Earth-like planet in habitable zone of distant star

#323

Post by bluGill » Sun, Jul 19, 2026, 1:39 PM UTC

palata wrote: post #322

bluGill wrote: post #317

Earlier quoted context omitted.

Problem is I'm not interested in insects. A new leader species of large mammal would interest me. Even discovering dinosaurs aren't extinct is neat but not something I'd care about.

It sounds to me like saying "I don't really care about football except the finals of the world cup. I wish we discovered alien football, that would interest me". I get the point, but it sounds like you just don't care about football in the first place.

There are people who care about football (soccer in the USA), and chear at all the home games even when the team is clearly going to lose every game this season. Then those who go to games when the team is winning. Then those who start going when it is clear the team will make the playoffs. Finally those who don't care and never go.

The above can be repeated for every other sport. I know someone not interested in the soccer world cup despite it being the most talked about event in the US now - but they are at the local kids lacrosse games (not a common sport in the US). I'm like that, I'm very interested in another cat if one is found, but I don't care about another insect. I'm not against you caring, it just isn't me.

Re: First atmosphere found on Earth-like planet in habitable zone of distant star

#324

Post by gregdaniels421 » Sun, Jul 19, 2026, 6:57 PM UTC

eru wrote: post #264

jjk166 wrote: post #258

Earlier quoted context omitted.

This is false. Earth's magnetic field does not significantly impact atmospheric loss. For comparison, Venus is closer to the sun and has no magnetic field, but has a substantially thicker atmosphere than earth.

Venus has lots all her lighter elements in the atmosphere. Basically no hydrogen left (not even in the form of water).

> Basically no hydrogen left (not even in the form of water).

There should be a decent amount left as sulfuric acid.

Re: First atmosphere found on Earth-like planet in habitable zone of distant star

#325

Post by eru » Sun, Jul 19, 2026, 11:57 PM UTC

gregdaniels421 wrote: post #324

eru wrote: post #264

Earlier quoted context omitted.

Venus has lots all her lighter elements in the atmosphere. Basically no hydrogen left (not even in the form of water).

> Basically no hydrogen left (not even in the form of water). There should be a decent amount left as sulfuric acid.

Yes, confirmed. Though depends on what you mean by 'decent amount'.

Re: First atmosphere found on Earth-like planet in habitable zone of distant star

#326

Post by tzfld » Mon, Jul 20, 2026, 10:25 AM UTC

smb06 wrote: post #187

I feel like I've been hearing about atmosphere on Earth-like planets for a while. Or maybe I've missed some nuance.

A little bit like news with signs of water found on Mars. Keep appearing as big news. It was maybe 15 years ago.

Re: First atmosphere found on Earth-like planet in habitable zone of distant star

#327

Post by myrmidon » Mon, Jul 20, 2026, 11:22 AM UTC

golem14 wrote: post #241

hparadiz wrote: post #106

Earlier quoted context omitted.

This requires sending something to at least about 548 AU and then effect falls off from there but anything you send that far will be going at a velocity that would keep it going. You would be in effective range for some time but basically you'd need to keep sending satellites to that distance in order to keep using the technique. You'd also want to send them into different directions in order to image different parts…

Thanks for that comment, it made me think. Couldn't you do something like a Hohmann transfer orbit ? As I understand it, adjusting the orbits far out there isn't as demanding as one might think (you don't have to spend the same energy you took to get out there to get into an orbit. Of course, this also means you will not be able to stay in one place and continuously map the same area, but you can map all the space wi…

If you circularize the orbit at 550 AU (which is costly but possible, at ~1km/s of delta-v), then you end up with an orbital period of >10000 years (to complete your whole-sky survey in one plane).

But first-- the price to get that circular orbit is steep, you end up imaging empty space for a lot of the time (no real way to "skip ahead") and your orbital speed vector makes you leave the observation cone for any interesting target pretty quickly.

In conclusion: You probably really want to stick with "one telescope probe per target system", and to give them one-shot orbits because those are cheap, reasonably fast and inside the observation cone (for your single target) for longer.

Re: First atmosphere found on Earth-like planet in habitable zone of distant star

#328

Post by peter_stokes » Mon, Jul 20, 2026, 1:32 PM UTC

timbit42 wrote: post #237

peter_stokes wrote: post #204

life does not exist on other planets (not considering contamination). I'll bet on it

The universe is bigger than the part of it we can see. The part we can see is large enough that there statistically has to be life out there, but it's also so large that we'll never sense them let alone communicate with or see them.

>there statistically has to be life out there

based on what

>but it's also so large that we'll never sense them let alone communicate with or see them.

unfalsifiable.

Re: First atmosphere found on Earth-like planet in habitable zone of distant star

#329

Post by detritus » Mon, Jul 20, 2026, 1:46 PM UTC

creesch wrote: post #142

detritus wrote: post #29

Earlier quoted context omitted.

Yeah, if your username is any indication of your age, you've possibly taken much the same trajectory of pessimism that I have. As a youth, I assumed we'd be hitting multiple Cs or bending space time when I was an adult; As an adult I thought we might get a percentage of C and conquer the solar system; Now I realise Just How Much Effort it would be to accomplish much of any value on our own Moon, never mind Mars. I st…

> Yeah, if your username is any indication of your age You might want to look up what the unix epoch is based on ;)

I'm well aware, but it could as-equally be because a lot of people default to 01/01 of their birth year when signing up to things online.

Re: First atmosphere found on Earth-like planet in habitable zone of distant star

#330

Post by pandoro » Fri, Jul 24, 2026, 8:52 AM UTC

jimbokun wrote: post #255

pandoro wrote: post #197

Earlier quoted context omitted.

Exactly. Imagine what would be possible after a billion year of technological evolution, heck even just 100'000 years. We already know that space time metric engineering is theoretically possible within our current understanding of physics, we don't have either the technology or access to energy density necessary to do it. And that's only within our limited understanding of how the universe works.

Could you expand on what “space time metric engineering” is?

The general idea is to deliberately shape the geometry of spacetime to allow for effects such as faster-than-light travel (relative to another region of spacetime).

Einstein's field equations link geometry to matter and energy:

G_μν = 8πG/c⁴ · T_μν

Left side describes how spacetime curves (the metric tensor). Right side represents what's causing the curvature (the stress-energy tensor): mass, energy, momentum. The usual approach is: you specify T_μν (what matter is where) and solve for the resulting curvature. Metric engineering takes the backward approach. You pick the geometry you want first: e.g a bubble that carries its contents faster than light relative to the outside universe. Then you work out what T_μν would have to be to produce that geometry: what distribution of energy and stress the equations demand.

The classic example of spacetime metric engineering is the Alcubierre drive.

The limitation with this is that the required T_μν has negative energy density in some regions (the bubble walls) which violate some assumptions about how "reasonable" matter behaves. But Quantum Field theory allows such local regions of negative densities and we have created such regions in labs experimentally already (Casimir effect). We "just" don't know how to sustain the effect at bigger (atomic) distances.