suppose solar system only had sun and earth?

"bubba griffith" <fatsgrobnik.DeleteThis@hotmail.com> wrote in message
news:1112582420.588500.269160@g14g2000cwa.googlegroups.com...
 > suppose the solar system only had the sun and our planet. no jupiter,
 > no mars, no venus, no nuttin' except sun and earth. would life still
 > be viable on earth? or, do we need other planets to balance things
 > out? why and how?
 >

Having a large gas giant or two further out helps suck up a great deal of
the potentially life-destroying asteroids that may otherwise splatter us off
the face of the earth.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

"Dorothy J Heydt" <djheydt.RemoveThis@kithrup.com> wrote in message
news:IEEL4t.E7H@kithrup.com...
 > In article <1112582420.588500.269160.RemoveThis@g14g2000cwa.googlegroups.com>,
 > bubba griffith <fatsgrobnik.RemoveThis@hotmail.com> wrote:
 >
 > or, do we need other planets to balance things
  > >out? why and how?
 >
 > Why should we? Remember Carl Sagan's line about how the
 > gravitational effect of Mars overhead in the sky at your birth is
 > a tiny fraction of the gravitational effect of the obstetrician
 > standing right next to you.
 >

"But how can that be? Mars is so much bigger than the doctor!"

or

"But dearie, it isn't the gravity. Its the Zodiacal influence of Mars that
determines your life."


*crawls off into a corner snickering*

--
Multiversal Mercenaries. You name it, we kill it. Any time, any reality.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

On Mon, 4 Apr 2005 03:46:05 GMT, djheydt DeleteThis @kithrup.com (Dorothy J Heydt)
wrote:

 >In article <1112582420.588500.269160 DeleteThis @g14g2000cwa.googlegroups.com>,
 >bubba griffith <fatsgrobnik DeleteThis @hotmail.com> wrote:
  >>suppose the solar system only had the sun and our planet. no jupiter,
  >>no mars, no venus, no nuttin' except sun and earth. would life still
  >>be viable on earth?
 >
 >If there was ONLY the sun and the earth AND NOT THE MOON, the
 >earth would be more like Venus and life-as-we-know-it would be
 >highly unlikely.

That statement seems a bit categorical considering how few Earthlike
planets we've had to compare our models of planetary formation to. Is
there any reference to back it up besides Niven's say-so? Even if it
really is the case, consider how little atmosphere Mars has despire
having no moons worth speaking of, and then size the planet in
question so that it's whatever intermediate size between Mars and
Venus that gives just the right atmospheric thickness.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

On Mon, 4 Apr 2005 14:24:01 +1000, "John" <junk RemoveThis @junk.com> wrote:
 >"bubba griffith" <fatsgrobnik RemoveThis @hotmail.com> wrote in message
 >news:1112582420.588500.269160@g14g2000cwa.googlegroups.com...
  >> suppose the solar system only had the sun and our planet. no jupiter,
  >> no mars, no venus, no nuttin' except sun and earth. would life still
  >> be viable on earth? or, do we need other planets to balance things
  >> out? why and how?
  >>
 >
 >Having a large gas giant or two further out helps suck up a great deal of
 >the potentially life-destroying asteroids that may otherwise splatter us off
 >the face of the earth.

This solar system doesn't have asteroids, though, so Lonely Earth
would be fine. One wonders where they all went after the Solar
system's formation, though, I'd expect there to be a lot of them
considering there were no other planets to soak them up. Something
smells artificial about this setup. <!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

"John" <junk.DeleteThis@junk.com> wrote in message
news:d2qfh2$ceb$1@perki.connect.com.au...
 >
 > "bubba griffith" <fatsgrobnik.DeleteThis@hotmail.com> wrote in message
 > news:1112582420.588500.269160@g14g2000cwa.googlegroups.com...
  > > suppose the solar system only had the sun and our planet. no jupiter,
  > > no mars, no venus, no nuttin' except sun and earth. would life still
  > > be viable on earth? or, do we need other planets to balance things
  > > out? why and how?
  > >
 >
 > Having a large gas giant or two further out helps suck up a great deal of
 > the potentially life-destroying asteroids that may otherwise splatter us
off
 > the face of the earth.
 >
 >

But there would be no comets and asteroids either.

Life itself might be viable, but would be more difficult, and intellectual
development of an intelligent species might well be very stunted.

The main problem of the "Sun and Earth only" scenario is its implausibility
in light of what we now think we know about solar-system formation. But if
you accept it for the purpose of a story, then physically the first
difficulty is that the rotation axis of Earth is more of a free parameter
that can vary chaotically, leading to drastic ice ages, etc. The Moon tends
to hold the Earth in a narrow range of axial inclinations. Mars, without a
large moon, can have much larger tilts than its current value of around 23
degrees; up to 50-60 degrees.

The second difficulty is that any intelligent life that develops is going to
have a very difficult time escaping from the idea of the geocentric model
and may never develop proper astronomy. Without a Mars, whence comes a
Kepler? Without astronomy, a Newton could never get started, because there
would be no mental analogy of a falling apple and falling Moon. Only by
making the leap to telescopic astronomy and discovering binary stars,
parallax and the doppler shift of stars during the annual cycle would
challenges to the predominant view be possible. (Pretty hard to do; it took
humans nearly 250-300 years from the invention of the telescope to get this
far.)

Also, there would be no eclipses to stimulate astronomical thought.

--
Mike Dworetsky

(Remove "pants" spamblock to send e-mail)<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

Bryan Derksen wrote:

 > On Mon, 4 Apr 2005 14:24:01 +1000, "John" <junk RemoveThis @junk.com> wrote:
 >
  >>"bubba griffith" <fatsgrobnik RemoveThis @hotmail.com> wrote in message
  >>news:1112582420.588500.269160@g14g2000cwa.googlegroups.com...
  >>
   >>>suppose the solar system only had the sun and our planet. no jupiter,
   >>>no mars, no venus, no nuttin' except sun and earth. would life still
   >>>be viable on earth? or, do we need other planets to balance things
   >>>out? why and how?
   >>>
  >>
  >>Having a large gas giant or two further out helps suck up a great deal of
  >>the potentially life-destroying asteroids that may otherwise splatter us off
  >>the face of the earth.
 >
 >
 > This solar system doesn't have asteroids, though, so Lonely Earth
 > would be fine. One wonders where they all went after the Solar
 > system's formation, though, I'd expect there to be a lot of them
 > considering there were no other planets to soak them up. Something
 > smells artificial about this setup.

There's a huge asteroid field between Mars and Jupiter. Presumably if
Jupiter wasn't there the early solar system bombardment would have
prevented early life from forming (or a stable atmosphere). The
Shoemaker-Levy comets and those like them could have hit the Earth as well.

The comment about the moon-Earth orbital is probably on target - Mars
goes through periodic changes in its geoid that Earth doesn't (with a
possible exception in the late Proterozoic, ca. 800 million years ago).

The reason Venus is like it is has nothing to do with the solar system -
Venus's internal engine is slowing down so mantle convection ceased to
clean the atmosphere of CO2 and SOx.

I suppose there is nothing fundamentally wrong with the premise that
there would be a single planet-star solar system, although one might
think that there would be a lot of debris to boot (i.e. take the
distribution of planet sizes in our current solar system and make Earth
the largest, then the next largest would be smaller than Mercury).

N<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

 > The main problem of the "Sun and Earth only" scenario is its
 > implausibility

Current ideas of the Moon's formation seem equally implausible. See
_The Big Splat_

 > in light of what we now think we know about solar-system formation. But
 > if
 > you accept it for the purpose of a story, then physically the first
 > difficulty is that the rotation axis of Earth is more of a free parameter
 > that can vary chaotically, leading to drastic ice ages, etc.

Yes, see _What if the Moon didn't Exist?_ an interesting book.

rms<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

 > _The Big Splat_, _What if the Moon didn't Exist?_ an interesting book.

I wanted to add _The Once and Future Moon_, one of the best books on the
physical moon and it's geology there is.

rms<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

 >This solar system doesn't have asteroids, though, so Lonely Earth
 >would be fine. One wonders where they all went after the Solar
 >system's formation, though, I'd expect there to be a lot of them
 >considering there were no other planets to soak them up. Something
 >smells artificial about this setup.

The Milky Way is a huge asteroid belt in our solar syatem<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

Dorothy J Heydt wrote:
 > In article <1112582420.588500.269160.RemoveThis@g14g2000cwa.googlegroups.com>,
 > bubba griffith <fatsgrobnik.RemoveThis@hotmail.com> wrote:
  >>suppose the solar system only had the sun and our planet. no jupiter,
  >>no mars, no venus, no nuttin' except sun and earth. would life still
  >>be viable on earth?

 > If there was ONLY the sun and the earth AND NOT THE MOON, the
 > earth would be more like Venus and life-as-we-know-it would be
 > highly unlikely

That theory enjoyed a vogue about thirty years ago, but I understand it
to have been abandoned.

Messing with counterfactuals is always problematic. One could suppose
that, /sans/ other planets, there would be no sweeping of space crud,
and the Earth would be subject to constant bombardment. Or one could
suppose not.

--
John W. Kennedy
A proud member of the reality-based community.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

Bryan Derksen wrote:
 > On Mon, 4 Apr 2005 03:46:05 GMT, djheydt.TakeThisOut@kithrup.com (Dorothy J Heydt)
 > wrote:
 >
 >
  >>In article <1112582420.588500.269160.TakeThisOut@g14g2000cwa.googlegroups.com>,
  >>bubba griffith <fatsgrobnik.TakeThisOut@hotmail.com> wrote:
  >>
   >>>suppose the solar system only had the sun and our planet. no jupiter,
   >>>no mars, no venus, no nuttin' except sun and earth. would life still
   >>>be viable on earth?
  >>
  >>If there was ONLY the sun and the earth AND NOT THE MOON, the
  >>earth would be more like Venus and life-as-we-know-it would be
  >>highly unlikely.
 >
 >
 > That statement seems a bit categorical considering how few Earthlike
 > planets we've had to compare our models of planetary formation to. Is
 > there any reference to back it up besides Niven's say-so?

It was a real theory before it was Niven's, but I think it's been abandoned.

--
John W. Kennedy
"Those in the seat of power oft forget their failings and seek only the
obeisance of others! Thus is bad government born! Hold in your heart
that you and the people are one, human beings all, and good government
shall arise of its own accord! Such is the path of virtue!"
-- Kazuo Koike. "Lone Wolf and Cub: Thirteen Strings" (tr. Dana Lewis)<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

bubba griffith wrote:
 > suppose the solar system only had the sun and our planet. no jupiter,
 > no mars, no venus, no nuttin' except sun and earth. would life still
 > be viable on earth? or, do we need other planets to balance things
 > out? why and how?


Jupiter acts as a "goalie" for lack of a better term. Planet killing
asteroids get sucked in by Jupiter's gravity pool and either become
moons or get destroyed. Without it Earth would have been wiped out
millions of years ago.

But that's 5th grade astronomy. Everyone knows that, except you Gaza.

- Jordan<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth? 

rms <rsquires DeleteThis @flashREMOVE.net> wrote:

  > > The main problem of the "Sun and Earth only" scenario is its
  > > implausibility
 >
 > Current ideas of the Moon's formation seem equally implausible. See _The
 > Big Splat_

I believe some astronomer once said that the best explanation for the
Moon and its many anomalies is observer error: it doesn't actually
exist.
--
Aaron Davies
Opinions expressed are solely those of a random number generator.
"I don't know if it's real or not but it is a myth."
-Jami JoAnne of alt.folklore.urban, showing her grasp on reality.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: suppose solar system only had sun and earth?