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Possible exposure of Earth to dense interstellar medium 2-3M years ago

nature.com

11–20 of 66 posts

Re: Possible exposure of Earth to dense interstellar medium 2-3M years ago

#11
are there no tree fossils from that era that can show one part of the year being different from the rest?

I remember reading that dinosaur meteorite was discovered to have fallen in spring by those marks

surely regular pattern of getting in-out of heliosphere be noticeable?

Re: Possible exposure of Earth to dense interstellar medium 2-3M years ago

#12
post #8

Presumably it has happened before in the history of the earth but it would be interesting to know what effects it had on life on earth and, by extension, the arrival and development of modern humans.

Before the history of the earth?

>... before in the history of the earth...

Re: Possible exposure of Earth to dense interstellar medium 2-3M years ago

#13

Very interesting paper! Proposes (with lower bound of 1.3% chance) that the solar system may have passed through a local interstellar cloud, which would have caused the heliosphere to shrink to smaller than the orbit of the earth (0.22 au) some 2-3 mya. This may have affected the Earth's atmosphere and climate. Scroll down for some cool illustrations of a simulation showing how the heliosphere would have been tiny wi…

That's one of those fun astronomy topics that is mind boggling to think of the forces involved to diminish the effect of Sol's solar radiation to that level.

Re: Possible exposure of Earth to dense interstellar medium 2-3M years ago

#14

Why does this make me feel a little dirty and exposed ? Like, who knows what kinda alien DNA strands or spores are carried by the ISM?! I wonder if it would be possible to track biodiversity increases caused by the transit? Assuming there is biological material in the ISM, perhaps some of it made it into our biosphere! Very fun!

Maybe it was a large cloud of mushroom spores:

https://en.wikipedia.org/wiki/Panspermia

Re: Possible exposure of Earth to dense interstellar medium 2-3M years ago

#15
post #6

Every square meter of a space ship passing through this at the speed of light would interact with ~3e13 hydrogen atoms per second. I don't know if I did this correctly but that's only ~27kJ per second of mass energy. I thought it would be a lot more.

> I thought it would be a lot more.

Yet another example of just how big space is, and how empty atoms are

Re: Possible exposure of Earth to dense interstellar medium 2-3M years ago

#16

Why does this make me feel a little dirty and exposed ? Like, who knows what kinda alien DNA strands or spores are carried by the ISM?! I wonder if it would be possible to track biodiversity increases caused by the transit? Assuming there is biological material in the ISM, perhaps some of it made it into our biosphere! Very fun!

Remember, modern humans appeared around 1.5-2M years ago, so this event, geologically speaking, happened shortly before the arrival of modern humans. Perhaps this event had something to do with us evolving.

Re: Possible exposure of Earth to dense interstellar medium 2-3M years ago

#17

Why does this make me feel a little dirty and exposed ? Like, who knows what kinda alien DNA strands or spores are carried by the ISM?! I wonder if it would be possible to track biodiversity increases caused by the transit? Assuming there is biological material in the ISM, perhaps some of it made it into our biosphere! Very fun!

Remember, modern humans appeared around 1.5-2M years ago, so this event, geologically speaking, happened shortly before the arrival of modern humans. Perhaps this event had something to do with us evolving.

Do you mean Homo Erectus or Homo Sapiens? Sapiens arrived around 300k years ago, according to Wikipedia. Erectus did indeed arrive around 2M years ago.

https://en.wikipedia.org/wiki/Human

https://en.wikipedia.org/wiki/Homo_erectus

Re: Possible exposure of Earth to dense interstellar medium 2-3M years ago

#18
post #6

Every square meter of a space ship passing through this at the speed of light would interact with ~3e13 hydrogen atoms per second. I don't know if I did this correctly but that's only ~27kJ per second of mass energy. I thought it would be a lot more.

> I thought it would be a lot more. Yet another example of just how big space is, and how empty atoms are

Every time i even remotely have the illusion of understanding it gets upended. I think that’s why i like it so much

Re: Possible exposure of Earth to dense interstellar medium 2-3M years ago

#19
post #6

Every square meter of a space ship passing through this at the speed of light would interact with ~3e13 hydrogen atoms per second. I don't know if I did this correctly but that's only ~27kJ per second of mass energy. I thought it would be a lot more.

In the space-ship's frame, it would be a lot more.
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