Why Is Venus Hell and Earth an Eden?
Key topics
The article discusses the differences between Earth and Venus, exploring why Earth is habitable while Venus is not, with comments debating various factors such as planetary formation, magnetic fields, and the role of human perspective.
Snapshot generated from the HN discussion
Discussion Activity
Very active discussionFirst comment
8m
Peak period
52
0-3h
Avg / period
14.5
Based on 160 loaded comments
Key moments
- 01Story posted
Sep 21, 2025 at 6:56 PM EDT
3 months ago
Step 01 - 02First comment
Sep 21, 2025 at 7:04 PM EDT
8m after posting
Step 02 - 03Peak activity
52 comments in 0-3h
Hottest window of the conversation
Step 03 - 04Latest activity
Sep 23, 2025 at 2:10 PM EDT
3 months ago
Step 04
Generating AI Summary...
Analyzing up to 500 comments to identify key contributors and discussion patterns
Want the full context?
Jump to the original sources
Read the primary article or dive into the live Hacker News thread when you're ready.
This scheme would have some negative aspects.
BTW, hydrogen on Mars is enriched in D by a factor of 5 relative to Earth.
The article says that volcanism is the reason, and that solar heating would not cause this result on its own, even though it's everyone's first guess.
This is not likely the sole reason, but it must be a factor.
Mercury does have a magnetic field, Mars does not.
It doesn't have a magnetic field, but that could be due to the slow rotation.
There would be little point in terraforming Mars. There’s plenty of places on Earth to terraform
In our lifetimes, unlikely. Over the next 1 million years? Maybe.
Meanwhile, SpaceX is preparing to start prepping Mars colonization in a few years.
I know, Elon's timelines always break. But his insane goals are also always reached after considerable delays.
https://en.wikipedia.org/wiki/The_100_(TV_series)
Our beloved natural balanced ecosystems are just an artifact of the fact that unbalanced systems change until they reach some equilibrium.
But acting on it at this point is tragic premature optimization. Musk isn't a stupid person so I have to think in his heart he knows his story is more about PR and being seen as a visionary as something that will actually be done in the next thousand or ten thousand years. Even if there is some climate catastrophe that causes 99% of the population to die out and any civilization to collapse, the remaining 1% are better off on Earth than trying to spend their limited manpower to get to Mars, even if some crazy trillionaire has established a beachhead there.
As an analogy, it feels like some person living paycheck to paycheck and having only $20 to spare at the end of each pay period and saving up that money ... not to invest it in some way that improves their lot, but to hire a tax attorney to help them plan how to shelter $1B in income in case they win the lottery.
Musk was initially written off initially as crazy for every one of his successful business ventures.
And it's his money to spend as he sees fit.
If it was so easy designing and launching rockets for 10% of the cost, why didn't anyone else do it? Why did nobody else make reusable rockets? Rockets that could land on the launch pad? The rapid turnaround and cadence of launches?
Musk did what NASA was unable to do.
BTW, the Saturn V rocket engines were scaled up V2 engines. The essential bits were from the V2 engine - cryo fuels, turbo pumps, nozzles cooled by the fuel, boundary layer cooling, baffles to make the engine stable.
The Saturn V engines were lovingly built by hand. Musk's engines are mass produced.
As for "every one" of his successful business ventures being called crazy, the first one was a dot-com online map of businesses in a given city. Did people say that was crazy? His next venture ended up getting acquired by Paypal, was that considered a crazy business? He invested in/took over Tesla -- I don't know if it was considered crazy or not at the time. SpaceX obviously is a great success. The brain control company -- we'll see. Grok -- nobody called that a crazy idea. Some of his other ventures, like hyperloop and the boring company, do seem more crazy but those escape your claim because they are in fact not successful. His solar roof company wasn't crazy, but it also isn't a success.
In short, Musk has no doubt had great successes, but there is no need to alter history to claim that at every turn he broke new ground when everyone else said it was crazy or impossible.
Nobody did it before.
> acquired by Paypal, was that considered a crazy business?
Before he proved it was profitable. BTW, every business venture I started was considered crazy by my peers.
> Grok
Musk was an early investor in AI.
The Boring Company is successful. It has found a profitable market boring holes for infrastructure cables and pipes.
People said him buying Twitter was crazy. Oops! (What annoyed me about that was I had some Twitter stock, and it was forcibly sold to Musk. I wanted X stock instead! Alas, it is private.)
I put my money where my mouth is. I've invested in TSLA and am a happy shareholder.
Such as an internet phone. Like a personal computer. Like a Xerox copier. Like jet engines. Like a pencil with an eraser on the other end. Like interchangeable parts. Like the circular saw. Like electric power utilities.
Look up Robert M. Salter at RAND:
"The Very High Speed Transit System" (August, 1972)
"Trans-Planetary Subway Systems -- A Burgeoning Capability" (February, 1978)
<http://www.rand.org/pubs/papers/P4874.html> PDF: <http://www.rand.org/content/dam/rand/pubs/papers/2008/P4874....>
<http://www.rand.org/pubs/papers/P6092.html> PDF: <http://www.rand.org/content/dam/rand/pubs/papers/2009/P6092....>
Similar / more: <http://en.academic.ru/dic.nsf/enwiki/6107059>
Going to Mars isn't a new concept, either. There are probably a thousand scifi stories about such.
But Musk is the first to take action.
What he's doing is freakin' awesome, and I wish for him (and humanity) to achieve it!
You can create habitats from scratch, or you can have colonies on the moon.
Even Mercury is better than Mars.
...how? It's further. It has no atmosphere. There is no water or carbon.
Mars's atmosphere is pretty useless for humans.
Oxygen, carbon, nitrogen and hydrogen make up 95+ percent of a human by mass. Mars has all four, the first three in the atmosphere.
Δv, the only metric that matters. Mercury is at 5.5 km/s from LEO, vs 3.6 km/s from LEO for Mars.
By contrast Mars is bizarrely similar to Earth. It has almost identical axial tilt resulting in a similar seasonal cycle, a similar annual cycle, extensive mineral resources, some atmosphere simplifying landing - providing protection from meteorites, etc. It has temperature ranges that, like Earth, vary wildly due to seasonality, but are locally consistent. For instance on a summer day near the equator, it hits about 20C on Mars. If not for the blood boilingly low atmosphere, it'd be down right comfy.
Anyhow, kind of a rambling disorganized comparison because I'm in a rush - but yeah, Mars is almost eerily Earth like. In that if life was a video game Mars would be the kind of obvious 'next level', to a degree that makes it feel scripted. Even some chemical reactions like the Sabatier Reaction [1] (Martian atmosphere + electrolyzed ice => methane + oxygen + water) just feel too convenient to be true, but they are.
[1] - https://en.wikipedia.org/wiki/Sabatier_reaction
Dig a bit, and temperatures even out. Same as on Mercury.
About the light: you are going to stay indoors anyway.
About gravity: spin! You can build something that looks a bit like a giant funnel, spin that, and live on the inside. If you set up the speed of rotation and degree of incline right, the centripetal force and the moon's gravity will combine to point perpendicular to the surface you are standing on.
You are right that Mars has some interesting peculiarities. But the logistics are a million times harder than getting to and from the moon. So good luck getting a rescue mission there.
In addition, I would advice against contaminating Mars with earth life, if we still want to study it, and figure out if it ever had life. (The moon is and always has been almost certainly sterile.)
But what would happen following a major asteroid impact is a massive amount of matter entering into the atmosphere and effectively blocking out the sun. This results in plantlife dying off which then results in the rapid death of everything on up the foodchain - we starve to death. Yet you'd still mostly be able to breathe the air, your blood wouldn't boil on atmospheric exposure, and so on - it'd still be a rather more pleasant place than Mars.
What Mars can offer is (1) a parallel civilization that can continue on and (2) a lifeboat to Earth. People can return, help reorganize systems of governance and restore order, rescue survivors, and generally get started rebuilding Earth in the case of a mass extinction event. "All" we need from Mars is for it to be relatively self sustaining. I say relatively in that it can provide for the basic necessities - food, habitation, energy, reproduction, and maintenance/repair/replication of those basic necessities. Everything else is a luxury.
And the timelines for that are far closer, even within our own lifetimes. I think this will become more clear over the next decade. China has generally been quite conservative with their space goals and overperforming, and their stated goal for the first crewed mission to Mars is 2033, and every 2 years afterwards to follow indefinitely, as part of a plan to establish a permanent presence on the planet. The first Starship launch to land on Mars will also likely be a game changer for people.
The only fundamental tech we're missing is a heavier launch vessel, which we've already developed in the past - and have actively in development in the present via Starship. China is also developing their own super heavy vessels. But these developments taking 8 years is quite conservative. We went from practically nothing in 1962 (having only just put a man into orbit, and barely at that) when Kennedy gave his to the Moon speech. 7 years later in 1969 - we'd be landing on the Moon. And that landing posed far greater difficulties than just an extended flight, let alone when they were building from nothing, and we have all of this knowledge and prior experience to build from.
After that he spent a whopping 437 days on Mir (which had about 1/3rd the pressurized volume of the already claustrophobic ISS) to see how the human body would respond to long-term duration in minimal gravity. Upon landing back on Earth this time he decided to get up and walk from the capsule to his rest point (astronauts are normally carried/rehabbed due to muscular atrophy + dysfunctional balance/orientation, even for far shorter stays), making a point of the fact that he was just fine. Dude was just a complete badass. The USSR would have beaten us to Mars if they hadn't collapsed in 1991.
In any case, it's probably a good idea to do a flyby because there will be, with near 100% certainty, some thing things we hadn't considered and others that we simply were not aware of. By first doing a flyby and then a landing you increase the chances of success. And the people doing the flyby will probably be mostly the same people doing a landing a couple of years later - so it'll be more like "See you soon."
[1] - https://en.wikipedia.org/wiki/Valeri_Polyakov#Cosmonaut_care...
At least in a billion years we can expect we would be either extinct already from our own actions, or hope to be advanced enough as a species to move Earth's orbital path out a touch every couple millennia to keep us in the Goldilocks zone.
Maybe by then we can terraform the Mars by crashing a few dozen comets and detritus from the asteroid belt into Mars to keep the Martian iron core, add heat enough to keep it molten and spinning for a while, add enough mass to get the gravity about 9.8 m/s2, reboot a tectonic cycle, combine 2 satellites into 1 good one, and try to add water to the system overall.
You know, just a regular Tuesday for whatever species we evolve into.
One of these is a challenge at the frontier, the other an exercise in stewardship. They attract different personalities.
No. It's some combination of cowardice, greed and ego, by those involved.
You can bet your ass those guys are not thinking about saving the species. Lol. Furthest thing from their minds.
Solve the Earth's problems on Earth instead, no need to run off to Mars.
That's just kicking the can down the road.
Who do you think are "those guys"? Talking Musk? NASA? All the people who have dreamt of traveling the stars the last 100 years?
Remember, we landed on the moon before Elon Musk was born. He's also not the first to talk about landing or living on Mars.
And it's not to hedge against us destroying the planet. It's to hedge against an asteroid or other occurrence we can't control.
Fun fact, the first person to mention colonising other planets is John Wilkens in the 17th century. I'm sure you'll find a way to connect that to Musk though.
https://en.m.wikipedia.org/wiki/Space_colonization
I'm going to steal this.
> content removed
> <red> This content may violate our terms of use or usage policies
If you admit that terraforming, even after it's 'done', will require an ongoing maintenance effort, it's simple (but not easy). Eg you can use satellites to spin up an artificial magnetic field to shield against solar wind.
However, I suspect terraforming planets is a waste. Far more bang for your buck to build habitats in space from scratch (eg out of asteroids), than to go down another gravity well. You can spin them for artificial 'gravity'. And you can situate them close to earth where logistics of resupply and communication and trade are much more favourable.
Otherwise, Mercury is the planet to colonise, not Mars.
Mercury gets extremely hot in the sun, and extremely cold at night. So if you dig a bit under the surface it all evens out. Pick the right latitude, and you can get basically any average temperature you feel like, including a comfortable 20C.
(Otherwise, even on the surface it's easy to get comfy temperatures, if you bring retractable parasols. Just don't expect to stroll around outside the base.)
Mercury has the benefit compared to Mars that solar power is extremely plentiful.
edit: Plus, it's nice to split our eggs into multiple planetary baskets. And I suspect people would feel a bit happier living on the surface of a chilly Mars than to become mole people on Mercury, even if it is easier. Maybe summer and winter homes?
The methods we could realistically launch into in our lifetimes would take thousands of years, not millions (but also not hundreds) [1]. Projects of these timescales have precedent in human history, usually with a healthy dose of religious zeal.
[1] https://en.wikipedia.org/wiki/Terraforming_of_Mars
They'd think you daffy.
Now beyond that, ask them to produce any manner of modern device with the precision and high consistency we have. Again, they'd think you mad, and think that such was impossible.
Yet here we are.
The next stage in our development via LLMs is not about AI helping humans. It's about robotics. Automated assembly. Robots (not Androids) able to interact with the environment and able to problem solve akin to say.. a mouse.
Soon, entire factories will be entirely automated. Many almost are. We don't need Von Neumann machines to see this future, but we will certainly have robots capable of building entire factories, collecting resources and processing them, and further building machines to spec. And those machines will be able to self-drive, self-operat autonomously.
Anyone playing typical resource games knows about bootstrapping, but once in the asteroid field we're basically resource infinite. Building engines to attach to asteroids, mining asteroids, building factories to create more robots and engines, all of it will be automated.
We toil at self-driving cars, yet this same tech enables self-driving robotics of all types.
So I honestly think that once we bootstrap in space, this sort of thing can happen fast, fast, fast. Decades to send hundreds of thousands of ice-rich resources to Mars.
The soil? Ah, genetic engineering. Really, this is an entirely new field, and frankly is beyond the danger yet benefit of nuclear science. We have the bomb, yet we have nuclear energy and medicine. Well genetics can obviously be far more deadly, and research all over the world, and startups, are already working on employing bacteria and organisms as self-replicating machines to do our bidding.
The dangers are in our face, but oh well! So if we presume survival, then once an atmosphere is produced we can seed the planet with organisms which can survive on rock and yet work with a mania to process it. It's OK if we immediately have moss like grass substitute everywhere. As long as it's working its magic, we get continued O2 production, and we can always create a rabbit pet or something that licks moss to survive. Or are tasty.
My point is, there are indeed many barriers. But we need to view them with where we will be in decades, not where we are now.
To go off on a tangent: two centuries ago was the height of the first industrial revolution (at least in Britain). The first time in history when this actually became realistic.
The Industrial Revolution was the first time we had sustained, broad based productivity growth year after year (even if only around 1%, which is quite low by modern standards).
Weirdly enough, we can see sustained productivity growth in artillery and guns long before the wider industry.
Another weird connection: sometimes people look at a toy 'steam engine' that the ancient Romans had access to (https://en.wikipedia.org/wiki/Aeolipile) and wonder if they could have had an industrial revolution. But, to make a proper steam engine you need a lot more than just the right idea. You need a lot of metallurgy and precise crafting.
Specifically one thing you need is precision crafted cylinders that gas can expand in to move a piston. Well, at the time of the Industrial Revolution, European nations had just spent several hundred years locked in existential competition over who can make precision crafted cylinders that gas can expand in to move a bullet.
I had thought due to the eons we'd simply have evolved, but even on shorter time frames there is the transhumanist possibility. When we can engineer rabbit that eats chlorine moss, I don't know what we're aiming for at all. "People" by then could have robust gut culture that just digests the regolith.
There's a difference between considering all this vs thinking it's realistic. It's speculation, as any forecast into the centuries ahead must be.
We're already working on crops that can grow in lunar and Martian regolith [1].
[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC4146463/
Multiple baskets is good, but why planetary?
If we're nuking each other on Earth, I find it unlikely we wouldn't aim a nuke or two at that group's colony on Mars.
The only thing a Martian colony is a hedge against is ecological collapse on Earth. Because we did something exceptionally stupid accidentally. Or because a rock came by to say hi.
Even then, Mars is colder than the Antarctic, drier than the Sahara, has lower air pressure than the top of Mount Everest, has soil poisoned like a superfund cleanup site, has no meaningful ozone layer, has no magnetosphere protecting against CMEs, has half our solar irradiance level, and occasionally has planet-spanning dust storms, so the bare minimum for colonising Mars must be able to survive worse than any possible thing we can possibly do to Earth and also some of the bigger rocks coming by to say hi.
Wouldn't it be far easier and much more useful to colonize the ocean floor than other planets? It is, after all, 70% of the surface area that just sits there.
It's like going to the gladiator pits to fight because someone was robbed and shot on the next street yesterday and you don't think your street is safe enough.
The Earth hasn't always been hospitale to humans, much less technological civilisation. Chances are, we'll have to do similar "maintenance" at home, too. (Easiest to grasp: deflecting asteroids.)
> I suspect terraforming planets is a waste. Far more bang for your buck to build habitats in space from scratch
This comes down to how biology works in zero and partial g. One of the most useful set of experiments we could be doing right now, in terms of colonisation, is putting lots of rats and whatnot in tiny space stations and letting their life cycles play out.
That would be great! It would strongly imply humans, over cycles of reproducing in space, would too. I suspect, unfortunately, we'd have to iron out some kinks first [1].
[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC8675004/
Animals in their natural habitat and humans (especially with modern healthcare) are responding very differently to environmental pressure: we would need to accept a high infant and child mortality rate to be able to evolve.
And the humans having a much longer lifetime and a much smaller amount of descendant means that even without technology we would evolve orders of magnitude slower than rats.
And: if rats can survive somewhere, it's a pretty small step to make it survivable for humans.
This is just a semantic punt to "stewardship". (Why is habitability capitalised?)
Why? Just spin the thing.
Sure. Let's put rats in centrifuges in space and see if they can reproduce successfully. Maybe there is a coriolis boundary. Maybe something weird happens.
But yeah, sticking rats in a centrifuge is probably a better first step than starting with humans.
We don't know this! We don't know how (or even if) an embryo develops under the Coriolis force, or with a gravity gradient.
I would say the key thing with Mercury is the ability to dig fast.
Thanks. I'm just parroting some lines I read a decade or so ago on a website that I didn't manage to dig up again. (I wonder if it's still online?)
> I would say the key thing with Mercury is the ability to dig fast.
Why? What are you afraid of?
First, night lasts 88 (earth) days on Mercury. So if you start digging at dusk, you have plenty of time.
Second, Mercury's daytime surface temperature is around 430C (~ 800F ~ 700K). We have plenty of materials, like steel, that can withstand these temperatures easily. Even aluminum only melts at 660C.
So you make a parasol out of steel and span it over your equipment. Important: you make the parasol just big enough to shade your equipment, but otherwise let it see as much of the sky as possible.
Mercury has no atmosphere. So during the day you normally have a small patch of the sky at around 5772K, the sun. The sun has about ~6.6 times the angular area on the sky as from earth. The rest of the sky looks as if it's about 3K in temperature, ie very cold. The effect averages out to Mercury's 700K surface temperature.
The parasol itself will attain the same average temperature as the rest of Mercury's surface (because it's exposed to the same conditions).
But for anyone in the shade under the parasol will replace a patch of sky at 5772K where the sun used to be with one at only 700K where the parasol now blocks the view.
If your parasol is supposed to cover more than just a single point with its shadow, than it needs to be big. From the perspective of each shadow covered point, the parasol will have a bigger angular area than the sun it shades.
So you not only replace some 5772K area with 700K, but also some of the previously 3K area with 700K. Overall, you can probably set up things so that you get something like a balmy 15C on average.
> I would say the key thing with Mercury is the ability to dig fast.
To come back to this: Mercury has lower gravity than earth, so I expect that 'soil' will probably not be as dense?
You can in principle create artificial magnetic fields. But yeah, you are better off just staying indoors most of the time under a big fat layer of regolith.
It seems hard to believe that this would actually work, even though I understand why it should. Although you have to do the digging starting in extreme temperature conditions without an atmosphere.
Venus has too much atmosphere. That's the problem.
Inner thought: here come the downvotes, baby!
That's some brave stuff to try to pull off.
Many people are risk averse and would find the total failure of many years of work at the very least very disappointing.
And then trying again 16 times.
(I've just learned there are plans to try one more time: https://en.wikipedia.org/wiki/Venera-17)
Well, they become some of the hottest missions pretty quickly!
That likely resulted in many species going extinct!
Many of our iron ore deposits we still mine today are from that rusting. (That iron used to be mostly dissolved in the oceans.)
Our present technology based on iron and steel owes itself to early life on Earth, from 1.6 to as much as 4 billion years ago. As with petroleum and coal-bed formation, a process unlikely to repeat in Earth's future. Iron ores are abundant, but still a finite resource.
<https://en.wikipedia.org/wiki/Banded_iron_formation>
The iron doesn't go anywhere (ok, except for the iron making up our space probes). It is infinitely recyclable.
That's what ores are. Ores are useful because they are concentrated, the result of some ore-formation or ore genesis process.
The "not going anywhere", after it's been dispersed throughout the lithosphere, is precisely the problem.
<https://en.wikipedia.org/wiki/Ore_genesis>
<https://www.epa.gov/facts-and-figures-about-materials-waste-...>
That's a loss of 2/3 of production to non-scrap effluvia on an annual basis. I'll let you work out the ultimate resource depletion cycle from that. Recycling is useful, but it's no magic bullet, and there are always losses.
The most heavily recycled metal in the US is lead, per USGS data and prior comments of mine, with recovery rates of about 75%, accounting for 40% of net production.
<https://news.ycombinator.com/item?id=20164506>
<https://news.ycombinator.com/item?id=26412585>
Source citation: "USGS 2020 Minerals Yearbook: Recycling — Metals"
<https://www.usgs.gov/centers/nmic/recycling-statistics-and-i...>
Considering that the amount of stuff in our world made from steel at any one time is steadily increasing this makes sense.
>The most heavily recycled metal in the US is lead, per USGS data and prior comments of mine, with recovery rates of about 75%, accounting for 40% of net production.
There's little to no "post consumer pre-recycler" use for lead whereas every tom dick and harry can find a use for some old pipes or beams or whatever.
I wasn't aware that concentrated stores of iron are also an important part of this story!
There's plenty of coal left, and we will likely never exploit it, because solar is getting so cheap.
Also, despite long prophecies, peak oil never arrived either. So it doesn't look like we are running out of that stuff.
Everything around us is bathed in warm oxygen, just waiting to catch fire! Our homes, our clothes, our fields, our possessions, …our hair. Ready oxidation brings vitality to Earth but it’s also ridiculously dangerous.
Whether or not Theia was the cause - having a fast-spinning Earth and huge satellite in a low orbit* make Earth's situation profoundly different from that of Venus.
* https://en.wikipedia.org/wiki/Moon#System_evolution for starters
Still a favorite after 30 years.
https://archive.org/details/NOVA_VenusUnveiled
182 more comments available on Hacker News