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Earth was born dry until a cosmic collision made it a blue planet

sciencedaily.com

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Re: Earth was born dry until a cosmic collision made it a blue planet

#191

Post by gtowey »

shireboy wrote: post #4

This could mean in the Drake equation ne -number of planets capable of life- is very small. A planet has to be hit with a comet big enough to deliver a large amount of water but not so big or fast to destroy it. And be in the Goldilocks zone of the star. Also the mass of the planet would play a part - gravity of more massive ones would be more likely to capture a comet. But again, too massive and I could see that ham…

If Mars contained significant amounts of water in its past as we suspect, that would mean we have n=2 just in our own solar system.

Re: Earth was born dry until a cosmic collision made it a blue planet

#192

Post by gcanyon »

ElFitz wrote: post #123
scarmig wrote: post #76

Earlier quoted context omitted.

It does assume that life must be associatable with a planet. It's a plausible assumption, but you could also hypothetically have life develop on a star itself or its remnants, comets, clouds of interstellar gas. Maybe even something more exotic than that (dark matter? some weird correlated statistical properties of the quantum foam?)

Andy Weir’s Project Hail Mary had an interesting take on that.

I was bothered by the nearly a-scientific-ness of PHM. The story was nicely done in general, but it feels like he pretends to be hard science fiction when he's really Star Trek-level.

Re: Earth was born dry until a cosmic collision made it a blue planet

#193

Post by brianpan »

ricksunny wrote: post #110

>was rich in volatile elements essential for life, such as hydrogen, carbon and sulphur. Today years old on learning that 'carbon' is a 'volatile element'. (I come to learn that astrogeology has a unique definition of volatile). • The summary's own source article points makes no reference to carbon being volatile. • The wikipedia article for 'volatiles' in the astrogeological sense makes no reference to carbon being…

Astrophysicsts would also call these "metals" (anything heavier than helium) so don't read too much into it. :D

https://sentinelmission.org/astrophysics-glossary/metallicit...

Re: Earth was born dry until a cosmic collision made it a blue planet

#194

Post by crazygringo »

macintux wrote: post #179
crazygringo wrote: post #165

Earlier quoted context omitted.

So? We build nuclear power plants and it's not exactly easy/efficient to extract uranium. Hard things are done all the time. Having coal/oil is pretty irrelevant in terms of whether a civilization can build spacecraft.

"and when we drain the planet dry of easily-accessible fossil fuels we’ve deprived any successor civilization of its opportunity to escape the planet." Successor. Whoever comes along after we've done ourselves in.

Huh? "We" is the human race, whatever civilization. What point are you trying to make? What I said stands, exactly how I said it.

Re: Earth was born dry until a cosmic collision made it a blue planet

#195

Post by shaky-carrousel »

shireboy wrote: post #4

This could mean in the Drake equation ne -number of planets capable of life- is very small. A planet has to be hit with a comet big enough to deliver a large amount of water but not so big or fast to destroy it. And be in the Goldilocks zone of the star. Also the mass of the planet would play a part - gravity of more massive ones would be more likely to capture a comet. But again, too massive and I could see that ham…

Not so much, because both Venus and Mars also have water. So whatever gave Earth water is common enough to also give it to the other inner planets.

Re: Earth was born dry until a cosmic collision made it a blue planet

#197

Post by PepperdineG »

howieburger wrote: post #73
buran77 wrote: post #45

Earlier quoted context omitted.

The equation itself makes no assumptions. But anyone trying to calculate something with it must. The last five factors in the equation will be filled in by assumptions based entirely on one data point, life on Earth. From your link: ne = the average number of planets that can potentially support life per star that has planets. fl = the fraction of planets that could support life that actually develop life at some poi…

Those variables come with embedded assumptions they are essential and meaningful to discovery of life and civilization elsewhere in the universe. For all we know civilization exists inside our car battery. Why assume it only exists on planets. It's not explicit in it's assumption but implicit assumption the equation is meaningful.

>For all we know civilization exists inside our car battery.

Rick Sanchez uses a microverse battery

Re: Earth was born dry until a cosmic collision made it a blue planet

#199

Post by watersb »

What are the chances of the Earth forming yet remaining dry?

Exoplanet surveys that I've seen in popular press can see rocky, dry planets. I'm not sure if that's just a selection bias in our current technology or if Earth with ocean and atmosphere is relatively rare.

Re: Earth was born dry until a cosmic collision made it a blue planet

#200

Post by quotemstr »

mr_toad wrote: post #148
quotemstr wrote: post #127

Earlier quoted context omitted.

Planetary collisions happen all the time . All of Mercury, Venus, Earth, and Mars in our solar system had them. We can see their signatures in other solar systems too: see https://en.wikipedia.org/wiki/List_of_extrasolar_planetary_c... Whatever the great filter is, it's not planetary-scale collisions during the accretion phase of solar system formation.

A couple of dozen collisions out of 6000+ known exoplanets. Not exactly common, but not freakishly rare either.

Those are just the ones we caught in the act. That we can see 6,000+ means that there are many more we don't see.
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