IIRC we had some really good answers from actual scientists about why magnetic field doesn’t do jack about the atmosphere, but idk why they’re not here. I’ll try to find it.

Mars has liquid core. This is known since 2003.

It’s actually more effective at preventing atmosphere from escaping. Intrinsic field causes polar wind as the particles just escape through that hole. Does not happen in an induced field.

The atmosphere blocks all that radiation…

The Moon isn’t even necessarily a stabilizer of axial tilt. If it was a bit bigger it would destabilize Earth’s tilt.

Note that this is because those are gigantic worlds that’s still glowing brightly from the heat they obtained from their very recent formation (these directly imaged planets are usually a few tens of million years old). We should be able to image not-visibly-glowing planets soon, but not as of today.

The Solar System is too old for anything but the Sun to glow (except collisions which are extremely rare too), and brightness of Solar System objects scale to distance to the power of four (2 from dimming sunlight, 2 from the distance itself), so any cold planet rapidly fades into invisibility.

That model’s out of date decades ago. Newer modelings find that with enough water, which Earth has, the dayside would be lush, and the substellar point would be really, really wet jungle as the ascending air dumps all its moisture down. You can read for more details in this blog.

When the Sun had just formed its luminosity was ~70% today’s, and so Earth back then would’ve received 70% its current light too. But the thing is, with carbon dioxide and other greenhouse gases, liquid water oceans can exist much further out than we are now. With just carbon dioxide the outer limit is around 40% Earth’s sunlight, so Earth has always been within the habitable zone.

Spotted in 1 second

I believe it’s because adding hydrogen isn’t the main way of nucleosynthesis. Check the alpha process out.

And getting rid of Earth would make Venus easier for Marvin the Martian to see Venus! Let the fight begin!

Honestly I love the idea of us spreading out, but only take what we need and keep our footprint low. Modify ourselves to life comfortably in alien environments if must. Maybe that sounds a bit too hippie (what does that mean?), but I immensely enjoy the diversity and history that celestial bodies offer that would be all too easily ravaged and destroyed if we act like mindless optimization swarms.

Because you don’t really need that many people? It’s possible to have trillions of people and leave all the planets minimally modified and here for future generations to study and play on. Terraforming is enough affront to these planets, dissembling them for a quintillion people who wouldn’t totally end up killing each other and destroy everything is just laughable. And this is coming from someone who works in a story where people routinely dissembles entire planetary systems.

How about us not going full on barbarian and destroy planets because big numbers cool

Oh right, thanks for reminding me of that effect. I concede.

Yeah, but the water here starts out as liquid, as stated in the question, I don’t think it would be frozen.

It would evaporate, actually. Water can only be gas or solid in vacuum, and the temperature of the sublimation point is far lower due to the lack of pressure. At Earth’s distance, there is more than enough irradiance to simply turn all the water into gas.

I’m responding to the other person.

A lot of things in planetary science can be handwaved away with impacts, that doesn’t mean it’s the correct answer for everything. Tidal-locking, atmospheric tides, rotation instability at very low rotation rates, are also present.

Surface temperature doesn’t scale linearly with irradiance.

Both are the same, it just depends on how you define 0 degrees tilt. If you define it as the direction of rotation (north pole is the pole where the planet pins counter clockwise when you look down on it), it’s upside down. If you define it by direction (north pole is the pole that points in the same direction as Earth’s), it spins backward.

If Venus today was Earth-like, fast rotation would’ve killed it.

Slow rotation means not a lot of wind to dissipate clouds forming on the dayside. That helps cool the planet down massively. I recall some works suggesting that Venus could’ve maintained habitability if we terraform it today and left it alone like that.

And Mars does have a molten core. Evidence was found since 2003 and again by InSight in 2021.

Liquid core does not automatically equate to an intrinsic magnetosphere.