How Did Earth Avoid a Mars-like Fate? Rocks May Have Clues

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https://phys.org/news/2022-07-earth-mars-like-fate-ancient-clues.html

I thought the moon saved earth from getting a battery of meteors?

That's a very fascinating article. I enjoy learning things about our planet.

Eventually, perhaps, but maybe only after  Two Early Planets Collided to Form the Moon .

Scientists have proposed many ideas for how the Moon formed.  A leading contender, the Giant Impact theory, speculates that when Earth was a young planet and just beginning to form, it was hit by another emerging planet named Theia, located nearby.  The collision caused both planets to temporarily splatter apart into globs of gas, magma, and chemical elements before reforming into the bodies we know today to be the Earth and Moon.  The research by Simon and Gargano is adding support that further confirms this theory.

Yes, that explains the origin of the moon. But the surface is dotted with impact craters which is why it looks like Swiss cheese, I'm speculating if the moon wasn't there then those objects might have hit the earth.

In 2017 oumuamua entered the Solar system from outside past the earth and then left back into deep space. This suggests the earth is subject to getting hit virtually at any time without warning.

Well, Earth is a bit bigger than Mars for one. This means that the Earth's core will take longer to cool down and will continue to generate an electromagnetic field that keeps the atmosphere from being stripped by the solar wind, like what happened to Mars.

Isn't Mars in the "Goldilocks zone" ?

It might be. But thats the very point. Even if it is in the Goldilocks zone its lack of protection by a magnetic field means it gets sterilized by a solar wind. So life might be able to form there (and indeed Mars did have liquid water in the past) but it gets zapped by the solar winds.

Also Earth is just as pockmarked by meteors as the moon. Its just less obvious because Earth is more geologically active, and has vegetation and so forth. So its able to cover up its blemishes better than can the moon.

It illustrates how precarious space is to evolving life on an orbiting planet in the goldilocks zone. It's no wonder they have to keep modifying the original Drake equation adding more and more mitigating factors as modifying variables that reduce the predictability of life in the universe.

If Mars is in the "Goldilocks Zone" it is very near to or just at the outer boundary.

Part of its problem is an insignificant magnetic field to protect an atmosphere, and the other part is insufficient gravity to hold on to an atmosphere.  Solar wind and radiation drove most of the atmo away.  What remains may not be there in a few million years.

That only adds to the reduction in probability of life in the "goldilocks zone" in other solar systems. Reinforces the idea we on earth are a product of sheer good luck

Yes. There are all kinds 'unknown unknowns' (to quote Donald Rumsfeld) out there. And as they become known they will probably drive the odds of life taking hold on other planets down rather than up.

A planet has to be big enough to retain the right kind of core to have a magnetic field to shield it, and to hold on to its atmosphere.

The Goldilocks zone probable moved over time. Probably did include Mars at one time in the distant past because we know that at one time it had liquid water.

The Moon probably does nothing to shield us from meteors. But it probably does something not yet known to help us. Like maybe keeping the earth's tilt stable. We dont know.

No other planet in the solar system has a moon as big (relative to the main planet) as our moon. Mars has two over grown boulders as moons (each an irregular rock about the size of Manhatten). The gas giants have all sizes of moons, and even moons larger in absolute size than the earth's moon (Gandymede is even bigger than planet Mercury). But none has a moon as large relative to the main planet as the moon is relative to the earth. Moon is a quarter the diameter of the earth. No other planet has a companion that relative size. With one exception. Pluto, and its moon Charon, are almost equal in size.