r/interestingasfuck • u/howimetyourcakeshop • 9h ago

Our moon being formed.

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u/ShaggyCan 9h ago edited 9h ago

Earth is a strange planet for this reason. Because Earth's core is so large in proportion to it's diameter it has a stronger magnetic field at the surface and is denser than a planet formed through normal gravitational accretion. If Earth was any lighter, it would have ended up like Mars, unable to hold it's atmosphere. Earth is probably at the very low end of habitability due to its size. Most exobiologists look at what we call super Earth's because they are more likely to have complex life. Another cool fact is that the further you go back in time the shorter the day lasted on Earth and the closer the moon was. 65 million years ago a day was around 23 to 23.5 hours long and the moon was 2 to 3 thousand km closer.

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u/daou0782 7h ago

And do you know there’s a very narrow window where planets have the right mass/density to allow for escape velocity?

So maybe larger worlds are more habitable but life on it is trapped in their gravity wells. And lighter planets don’t normally have cores large enough to allow for magnetic fields strong enough to protect their atmospheres.

Truly a rare earth.

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u/j2m1s 4h ago

There are many other ways to leave the planet, it's not just chemical rockets, there is Project Orion which has the concept of using nuclear bombs detonating behind rockets in a controlled manner to send them to space for example, if they are intelligent life desperate to leave their star system knowing that they are going to die in it's red giant state, they would go out by even doing that!.