[pasmembers] Re: Life Beyond Earth
- From: Robert Ewing <rrewing9@xxxxxxxxx>
- To: pasmembers@xxxxxxxxxxxxx
- Date: Mon, 25 Aug 2014 11:53:05 -0700
Thanks Mike!
On Aug 25, 2014 9:43 AM, "CenturyLink Customer" <primefactory@xxxxx> wrote:
> Had to put my two cents in. Once the sun ignited it has varied little in
> output. Inside of Jupiter's orbit we have asteroids and zodiacal light
> which is dust not ices because of the stellar wind and light intensities.
> Even now this slowly strips rocky planets of their atmospheres and
> left only the heavier gases (no H & He). Comets begin to sublimate when
> they get closer than Jupiter and quickly lose their mass. Objects like the
> Earth are a very small target. The most important point against comets is
> because they formed outside our solar system they have isotopic ratios that
> do not match terrestrial values. Only Io is too hot to have ice of all the
> moons of the gas giants. Isotope ratios of ice on these moons are much
> closer to terrestrial values. Asteroids beyond Jupiter are also ice covered
> but not as thick as these moons. These satellites had close encounters with
> other moons that reversed the orbits of the smaller moon and would eject
> the more massive moon. I have given lectures on how the Earth was struck
> 1.8 billion years ago in the Pacific by a moon of Neptune that had a thick
> layer of ice and hydrocarbons that made it as large as Mars. You can double
> the amount of water the Earth has because the Moho is a buried
> mineralized ocean that is still trying to reach the surface through
> volcanics.
>
>
> Mike Marron
>
> ------------------------------
>
> *From: *"Robert Ewing" <rrewing9@xxxxxxxxx>
> *To: *pasmembers@xxxxxxxxxxxxx
> *Sent: *Sunday, August 24, 2014 8:02:10 PM
> *Subject: *[pasmembers] Re: Life Beyond Earth
>
> Sorry I forgot to mention that as the Earth was forming (early on) comets
> could have struck it and incorporated water into the Earth as well...the
> Earth would have to have accumulated enough mass however so that the escape
> velocity for water molecules would not be exceeded.....because the
> temperature was not cold at that point......hence difficult for liquid or
> ice to accumulate here......
> On Aug 24, 2014 7:53 PM, "Robert Ewing" <rrewing9@xxxxxxxxx> wrote:
>
>> Hey. Bob Ewing here, from PVCC.....
>>
>> I have always had a difficult time with the comet theory as well,
>> because, the Earth has been outgassing for 4 billion years plus; (ie:
>> volcanic activity); so there had to be primordial water inside the Earth
>> from it's formation from the solar nebula; although maybe in the form of
>> vapor.
>> H2O is actually a very common molecule in space. But, the Earth has been
>> struck by many comets as well, so certainly some of the water has come from
>> them ......hard to say what %
>>
>> Volcanoes emit steam (water) as the primary gas. CO 2 is usually second.
>>
>> There are hydrated minerals too and maybe some of these have been
>> recycled inside the Earth over time, as has sediment containing water
>> (marine). When this material is melted inside the Earth they would release
>> the water as steam...
>>
>> Complicated issue!
>>
>> :-)
>>
>> Bob
>>
>> On Aug 24, 2014 5:26 PM, "Alex Vrenios" <axv@xxxxxxx> wrote:
>>
>>>
>>> I just happened to watch the NOVA program, "Finding Life Beyond Earth."
>>> The focus seemed to be on some new thinking about how an exoplanet doesn't
>>> have to be in a "sweet spot," at that not-too-hot and not-too-cold distance
>>> from it's star, to foster life. There are other energy sources, like
>>> geothermal, e.g., that can suffice, admitting many other, more distant
>>> planets and moons to the potentially inhabited bodies in a solar system. A
>>> source of energy, water and organic compounds were referred to as the
>>> "trifecta" of life-forming ingredients.
>>>
>>> Pretty cool, but what caught my interest was the water.
>>>
>>> A long time ago, a budding young scientist (in a geology class, I think)
>>> asked one of those questions that stop internationally acclaimed scientists
>>> in their tracks, "Where did all that water come from?" Referring to the
>>> fact that about 3/4 of the Earth's surface is covered with water, yet there
>>> doesn't seem to be a reason for that.
>>>
>>> The answer for many years has been a bombardment from comets which, as
>>> we all believe, are made mostly of ice: the "dirty snowballs" of stellar
>>> objects. I think that that's a lot of comets! It never seemed to me to be a
>>> very satisfying solution, no pun intended.
>>>
>>> This NOVA program referred to an accretion disc as dust, gas *and*
>>> water. Wikipedia's definition is too vague. Britanica.com
>>> <http://britanica.com/> says "dust, gas and other tangled molecules." I
>>> don't remember hearing anyone state that water was a major component of the
>>> material from which planets may form before now. But then I'm not exactly a
>>> main-stream astrophysicist, so maybe some of you can elaborate...
>>>
>>> Alex
>>>
>>
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