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Question about early Earth



 
 
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  #1  
Old February 6th 06, 11:21 PM
blue.planet blue.planet is offline
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Default Question about early Earth

Was the Moon in a close Earth orbit essential in preventing a runaway greenhouse effect like we see on Venus. The Earth was much more volcanically active in it's youth and would have put out much more CO2 and other greenhouse gases. Did the Moon siphon off much of the Earth's atmosphere in earlier times.

I'm trying to figure what sort of planets we'll be looking for in the future that will be possible candidates for life outside our solar system. Obviously the gas giants we've found in close orbit around other stars couldn't support life. Would being in the right orbit around the right sized star be enough to create the conditions for terrestrial type life, or is a double planet like our Earth-Moon neccessary?

Last edited by blue.planet : February 7th 06 at 01:30 AM.
  #2  
Old February 10th 06, 07:10 PM posted to sci.space.science
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Default Question about early Earth


blue.planet wrote:
Did the Moon siphon off much of the Earth's
atmosphere in earlier times.


No. Earth's gravity is substantially stronger than the moon's, so the
moon couldn't pull away atmosphere.

IIRC, oceans are pretty good about sucking up excess CO2.

Would being in the right orbit around the right sized star be
enough to creat the conditions for terrestrial type life, or is
a double planet like our Earth-Moon neccessary?


I don't think it's necessary, but it can help. At a minimum, a large
moon helps by minimizing random flips in a planet's tilt, which can
have drastic effects on the environment.

Mike Miller

  #3  
Old February 13th 06, 05:49 AM
blue.planet blue.planet is offline
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Quote:
Originally Posted by
blue.planet wrote:
Did the Moon siphon off much of the Earth's
atmosphere in earlier times.


No. Earth's gravity is substantially stronger than the moon's, so the
moon couldn't pull away atmosphere.

IIRC, oceans are pretty good about sucking up excess CO2.

Would being in the right orbit around the right sized star be
enough to creat the conditions for terrestrial type life, or is
a double planet like our Earth-Moon neccessary?


I don't think it's necessary, but it can help. At a minimum, a large
moon helps by minimizing random flips in a planet's tilt, which can
have drastic effects on the environment.

Mike Miller
thanks for the info Mike
  #4  
Old February 20th 06, 09:27 AM posted to sci.space.science
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Default Question about early Earth


blue.planet wrote:
Was the Moon in a close Earth orbit essential in preventing a runaway
greenhouse effect like we see on Venus. The Earth was much more
volcanically active in it's youth and would have put out much more CO2
and other greenhouse gases. Did the Moon siphon off much of the Earth's
atmosphere in earlier times.

I'm trying to figure what sort of planets will be looking for in the
future that will be possible candidates for life outside our solar
system. Obviously the gas giants we've found in close orbit around
other stars couldn't support life. Would being in the right orbit
around the right sized star be enough to creat the conditions for
terrestrial type life, or is a double planet like our Earth-Moon
neccessary?


--
blue.planet



blue.planet,
there exists an "ecosphere" or "goldilocks" region around every star
where a planet can have liquid water... Venus is just inside this
region so it never cooled down enough for liquid water to exist...
water is much more erflective than land surface.. so this might be
another important reason for the earth to cool down. On venus all wate
exists in the form of water vapour.. and water vapour IS a greenhouse
gas.. So it would aid in heating up the planet and not cooling it down.
By the way, your hypothesis of the moon siphoning off gas from the
Earth is unlikely. Sure, the moon was a lot closer to the Earth but it
served to increase tidal force on Earth and also volcanic activity(for
eg Io, Jupiter's moon has volcanic activity attributed to massive tidal
forces from Jupiter). So a closer moon would aid volcanic activity and
not stop it...as for your other question, a double planet may be a
necessity as studies have shown that the moon helps stabilize the
Earth's orbit and reduce wobbling about its axis and moderate the
seasons. However until we find another planet with life bearing
conditions WITHOUT a large satellite it remains to be proved......
Gautham Ram. you can contact me at
Looking forward to hear from you..

  #6  
Old February 24th 06, 09:49 PM posted to sci.space.science
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Default Question about early Earth


blue.planet wrote:
Was the Moon in a close Earth orbit essential in preventing a runaway
greenhouse effect like we see on Venus. The Earth was much more
volcanically active in it's youth and would have put out much more CO2
and other greenhouse gases. Did the Moon siphon off much of the Earth's
atmosphere in earlier times.


In the 60s it was speculated that the Moon is the reason the Earth's
atmosphere isn't like that of Venus. The idea was that, even though
its gravity is so much less than Earth's, it would perturb enough
molecules to escape velocity over time that the amount of atmosphere
would be depleted. Larry Niven picked up on that and incorporated it
into at least two stories. It was never a widely held hypothesis, and
since it was first proposed better modeling indicates that Venus' fate
was sealed simply by its proximity to the Sun.

I once asked about that here years ago, and Henry Spencer said that a
lot of science speculation that Niven used in his stories came from
Tommy Gold, an iconoclastic astronomer who was part of the steady state
universe crowd (with Fred Hoyle) and also is known for having gotten in
a row with NASA during Apollo. All of this is from memory and possibly
way inaccurate.

  #7  
Old February 26th 06, 02:22 AM posted to sci.space.science
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Default Question about early Earth

If you read the original work on this issue, you find it applies
very well to the Earth in the solar system, and not at all outside the
solar system.


Oh, good, that'll be handy for some sci-fi projects I'm working on.
Less need for every habitable planet to have big moons.

Do you have a link to the original work?

Mike Miller

  #8  
Old February 26th 06, 09:33 PM
blue.planet blue.planet is offline
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First recorded activity by SpaceBanter: Feb 2006
Location: Canada
Posts: 18
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Quote:
Originally Posted by
In the 60s it was speculated that the Moon is the reason the Earth's
atmosphere isn't like that of Venus. The idea was that, even though
its gravity is so much less than Earth's, it would perturb enough
molecules to escape velocity over time that the amount of atmosphere
would be depleted. Larry Niven picked up on that and incorporated it
into at least two stories. It was never a widely held hypothesis, and
since it was first proposed better modeling indicates that Venus' fate
was sealed simply by its proximity to the Sun.

I once asked about that here years ago, and Henry Spencer said that a
lot of science speculation that Niven used in his stories came from
Tommy Gold, an iconoclastic astronomer who was part of the steady state
universe crowd (with Fred Hoyle) and also is known for having gotten in
a row with NASA during Apollo. All of this is from memory and possibly
way inaccurate.
Larry Niven is probably where I got that idea.

It's interesting to read that the moon actually stabilizes the Earth and makes it more habitable. Also that liquid water may have played an important role in reflecting solar radiation to keep the world cool.

Thanks.
  #9  
Old March 15th 06, 08:43 PM posted to sci.space.science
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Default Question about early Earth

wrote:
Was the Moon in a close Earth orbit essential in preventing a runaway
greenhouse effect like we see on Venus. The Earth was much more
volcanically active in it's youth and would have put out much more CO2
and other greenhouse gases. Did the Moon siphon off much of the Earth's
atmosphere in earlier times.


As we learn more the answer increasingly seems to be that the earth
was "unstable" before life became so dominant. Prior to this there were
a number of complete freeze-overs where the entire planet was covered in
ice. It is believed C02 built up from volcanoes, causing rnaway
greenhouse and melting the ice. The CO2 would then be react chemically
with the now-open oceans, scrubing it back out.

lot of science speculation that Niven used in his stories came from
Tommy Gold, an iconoclastic astronomer who was part of the steady state
universe crowd (with Fred Hoyle) and also is known for having gotten in
a row with NASA during Apollo.


No, pretty good actually. Gold was the guy that got onto TV by
claiming the moon probes would sink in the miles-thick dust on the moon.
OF COURSE it's miles thick, its been there practically forever and
there's no mechanism to solidify it back into rock like there is here.

So they built the landers and tested. Nope, no problem. But Gold
wouldn't stop even when confronted by direct counterexample. The TV
robots eventually gave up listening to him -- something that no longer
happens unfortunately.

He still turns up, unnamed, in various creationist books. Why?
Because the lack of thick dust on the moon means it can't be very old,
right?

Maury
 




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