Comet"s Tail

David You said it all when you said "No one knows" That means you and I
can discuss this with an open mind. We have to think the solar system
had to be much larger(a cloud) before the sun became a star. Gravity
might have tamed much chaos in the early phase of the solar system.
Possibly comets are showing how chaotic it was. Their exotic orbits,and
being much bigger could have caused great collisions with smaller
rock planets(knocking them out of proper orbit) What would have happened
to Earth if it was hit the way Jupiter was hit by the Levy Shoemaker
comets? Bert

During a perfect moment of peace at Sun, 05 Oct 2003 07:09:11 GMT,
"Painius" interrupted with:

It seems to me that such an impact would throw debris off
in many directions, and i find it a stretch to believe that the
greatest part of this debris would clump back together
before our Sun's fusing and the ensuing solar wind blowout.

The issue is that, given known laws of Newtonian Physics, you can work
backwards to find the mass and angle of impact required to to do
exactly what is required. That is, the material is not flung every
where and reforms into the Moon.

One of the problems with the moon is that its regolith is very similar
in composition to the ealiest rocks on Earth. Original ideas where
that both bodies formed form the same material but it's harder to make
that work than the impactor theory.

HTH. HAND.

During a perfect moment of peace at Sun, 05 Oct 2003 07:09:11 GMT,
"Painius" interrupted with:

It seems to me that such an impact would throw debris off
in many directions, and i find it a stretch to believe that the
greatest part of this debris would clump back together
before our Sun's fusing and the ensuing solar wind blowout.

The issue is that, given known laws of Newtonian Physics, you can work
backwards to find the mass and angle of impact required to to do
exactly what is required. That is, the material is not flung every
where and reforms into the Moon.

One of the problems with the moon is that its regolith is very similar
in composition to the ealiest rocks on Earth. Original ideas where
that both bodies formed form the same material but it's harder to make
that work than the impactor theory.

HTH. HAND.

"David Knisely" wrote in message om...

"Painius" wrote in message...
...

"David Knisely" wrote in message m...

. . . The theory is that the Earth was hit by a large body possibly as
big as Mars very early in its history or as it was forming. The
debris released into space from that impact eventually collected into
what would eventually form the moon. Computer simulations of such an
event have shown that the idea does work if conditions are right. The
impactor released a tremendous amount of energy that altered the form
of the material ejected from the impact point, depleting it of a
number of the more volatile elements and changing its minerology to
some extent. Thus, the lunar rocks would *not* be identical to the
rocks found on the surface of the Earth. Its not a bad theory at all,
but a workable one which may, in fact, be true.

David Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org

While i realize that this is the leading hypothesis and has
withstood over 25 years of scrutiny, and while i am sorry
to report that i have no better ideas about the origin of our
mysterious Moon, i *still* don't like this theory.

If we accept this theory as correct, then we are accepting
that a large, perhaps Mars-sized, object collided with the
early Earth and produced enough debris thrown out into
space to clump back together and form the Moon.

It seems to me that such an impact would throw debris off
in many directions, and i find it a stretch to believe that the
greatest part of this debris would clump back together
before our Sun's fusing and the ensuing solar wind blowout.

It probably did throw debris off in many directions, and it probably
did throw off a good deal more mass than the moon currently has. As I
stated, some may have gone into solar orbit, while a lot probably just
fell back onto the primitive proto-earth. All that is required
however is that enough mass is left over in some kind of irregular
orbital band that it can eventually come together to form a body the
size and mass of our moon. The solar wind only blows out very fine
debris (heavier stuff blown into solar orbit actually experiences drag
and gets pulled down towards the sun). Once in orbit, the debris would
begin to collect around the largest remaining fragments.

I also have a problem with it clumping back together so
close to the ecliptic, only 5 degrees off.

There is not a real problem with this, as the entire solar system
formed from a large irregular cloud to yield objects orbiting along a
similarly-narrow plane. Such a cloud of debris would have a plane of
mean angular momentum, although individual fragments would undoubtedly
have components of the motion somewhat perpendicular to the plane.
After collisions and interactions canceled out the components of
momentum perpendicular to the plane of the mean motion, you would be
left with a similar narrow plane or belt of debris. Again, computer
simulations of such an impact and debris release have shown that it is
possible to form a moon-like body in orbit around the Earth with this
collision model.

These are two very long stretches for me as regards this
Moon origin theory.

No more than the "stretch" required to slow-down and capture a
moon-sized body from a solar orbit into a Earth orbit which was much
closer to the Earth than it is now. Evidence from the distant past on
the length of the Earth's day, as well as current measurements of
lunar recession, shows that this is true. Without some other
substantial interaction or drag, doing this kind of orbital braking
and capture requires a very stringent set of conditions which are
somewhat unlikely to say the least. Such a close pass would more
often result in either just a change in the form of the solar orbit of
the incoming body, or a collision with the Earth, rather than capture
into a stable (and *close* in) orbit. Most objects which are captured
into orbit around another body are usually in distant outer orbits, as
the energy required for such a capture is much smaller than that
needed to put a body into a close orbit. Evidence has shown that
large-scale impacts were common in solar system during its formation
as well as during its early history. The collision theory is no more
far-fetched than the other theories of the origin of the moon.

I sincerely hope that astronomers have not made a final
decision on this and have consequently stopped thinking
on the matter. To me, the origin of our Moon remains a
delicious mystery!

Astronomers can't make a "final decision" on it, since there is no way
to be certain which theory (if any) is correct. However, unlike
Bert's assertion of it being a "fairy tale", the impact theory is just
as valid as any capture one. Clear skies to you.

David Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org

Thanks, David, after reading this and more on the theory, i
must accept it as the most plausible of the Moon-origin
theories.

I saw recently where scientists believe that it was this very
collision that formed the Moon that also may have given
Earth the type of atmosphere (reducing) that it needed to
form living things. This leads to the ideas... "no Moon, no
Life," and that if a large satellite or binary planet system is
required for life, this may lower the chances of finding life
elsewhere in the galaxy...

Would appreciate hearing your thoughts on this!

happy days and...
starry starry nights!

--
Ode Man Dying

So I fear I'm not long for this planet my friends,
And I'll miss you the moment I leave,
After that I've no clue just what happens my friends,
And I ask only that you don't grieve.

For I've lived a long life full of loving my friends,
And in this much I know you'll believe...
There is nothing on Earth more important my friends,
Than the loving relations you weave.

Paine Ellsworth

"David Knisely" wrote in message om...

"Painius" wrote in message...
...

"David Knisely" wrote in message m...

. . . The theory is that the Earth was hit by a large body possibly as
big as Mars very early in its history or as it was forming. The
debris released into space from that impact eventually collected into
what would eventually form the moon. Computer simulations of such an
event have shown that the idea does work if conditions are right. The
impactor released a tremendous amount of energy that altered the form
of the material ejected from the impact point, depleting it of a
number of the more volatile elements and changing its minerology to
some extent. Thus, the lunar rocks would *not* be identical to the
rocks found on the surface of the Earth. Its not a bad theory at all,
but a workable one which may, in fact, be true.

David Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org

While i realize that this is the leading hypothesis and has
withstood over 25 years of scrutiny, and while i am sorry
to report that i have no better ideas about the origin of our
mysterious Moon, i *still* don't like this theory.

If we accept this theory as correct, then we are accepting
that a large, perhaps Mars-sized, object collided with the
early Earth and produced enough debris thrown out into
space to clump back together and form the Moon.

It seems to me that such an impact would throw debris off
in many directions, and i find it a stretch to believe that the
greatest part of this debris would clump back together
before our Sun's fusing and the ensuing solar wind blowout.

It probably did throw debris off in many directions, and it probably
did throw off a good deal more mass than the moon currently has. As I
stated, some may have gone into solar orbit, while a lot probably just
fell back onto the primitive proto-earth. All that is required
however is that enough mass is left over in some kind of irregular
orbital band that it can eventually come together to form a body the
size and mass of our moon. The solar wind only blows out very fine
debris (heavier stuff blown into solar orbit actually experiences drag
and gets pulled down towards the sun). Once in orbit, the debris would
begin to collect around the largest remaining fragments.

I also have a problem with it clumping back together so
close to the ecliptic, only 5 degrees off.

There is not a real problem with this, as the entire solar system
formed from a large irregular cloud to yield objects orbiting along a
similarly-narrow plane. Such a cloud of debris would have a plane of
mean angular momentum, although individual fragments would undoubtedly
have components of the motion somewhat perpendicular to the plane.
After collisions and interactions canceled out the components of
momentum perpendicular to the plane of the mean motion, you would be
left with a similar narrow plane or belt of debris. Again, computer
simulations of such an impact and debris release have shown that it is
possible to form a moon-like body in orbit around the Earth with this
collision model.

These are two very long stretches for me as regards this
Moon origin theory.

No more than the "stretch" required to slow-down and capture a
moon-sized body from a solar orbit into a Earth orbit which was much
closer to the Earth than it is now. Evidence from the distant past on
the length of the Earth's day, as well as current measurements of
lunar recession, shows that this is true. Without some other
substantial interaction or drag, doing this kind of orbital braking
and capture requires a very stringent set of conditions which are
somewhat unlikely to say the least. Such a close pass would more
often result in either just a change in the form of the solar orbit of
the incoming body, or a collision with the Earth, rather than capture
into a stable (and *close* in) orbit. Most objects which are captured
into orbit around another body are usually in distant outer orbits, as
the energy required for such a capture is much smaller than that
needed to put a body into a close orbit. Evidence has shown that
large-scale impacts were common in solar system during its formation
as well as during its early history. The collision theory is no more
far-fetched than the other theories of the origin of the moon.

I sincerely hope that astronomers have not made a final
decision on this and have consequently stopped thinking
on the matter. To me, the origin of our Moon remains a
delicious mystery!

Astronomers can't make a "final decision" on it, since there is no way
to be certain which theory (if any) is correct. However, unlike
Bert's assertion of it being a "fairy tale", the impact theory is just
as valid as any capture one. Clear skies to you.

David Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org

Thanks, David, after reading this and more on the theory, i
must accept it as the most plausible of the Moon-origin
theories.

I saw recently where scientists believe that it was this very
collision that formed the Moon that also may have given
Earth the type of atmosphere (reducing) that it needed to
form living things. This leads to the ideas... "no Moon, no
Life," and that if a large satellite or binary planet system is
required for life, this may lower the chances of finding life
elsewhere in the galaxy...

Would appreciate hearing your thoughts on this!

happy days and...
starry starry nights!

--
Ode Man Dying

So I fear I'm not long for this planet my friends,
And I'll miss you the moment I leave,
After that I've no clue just what happens my friends,
And I ask only that you don't grieve.

For I've lived a long life full of loving my friends,
And in this much I know you'll believe...
There is nothing on Earth more important my friends,
Than the loving relations you weave.

Paine Ellsworth

In message ,
Painius writes

I saw recently where scientists believe that it was this very
collision that formed the Moon that also may have given
Earth the type of atmosphere (reducing) that it needed to
form living things. This leads to the ideas... "no Moon, no
Life," and that if a large satellite or binary planet system is
required for life, this may lower the chances of finding life
elsewhere in the galaxy...

Interesting! I thought current theory was that the early Earth didn't
have a reducing atmosphere, but the sort of nitrogen/carbon dioxide mix
that Mars and Venus still have.
Apparently the latest variation on the "Big Splat" is that the Earth was
hit by a much bigger object than previously thought, and before it had
reached its full size.
--
"It is written in mathematical language"
Remove spam and invalid from address to reply.

In message ,
Painius writes

I saw recently where scientists believe that it was this very
collision that formed the Moon that also may have given
Earth the type of atmosphere (reducing) that it needed to
form living things. This leads to the ideas... "no Moon, no
Life," and that if a large satellite or binary planet system is
required for life, this may lower the chances of finding life
elsewhere in the galaxy...

Interesting! I thought current theory was that the early Earth didn't
have a reducing atmosphere, but the sort of nitrogen/carbon dioxide mix
that Mars and Venus still have.
Apparently the latest variation on the "Big Splat" is that the Earth was
hit by a much bigger object than previously thought, and before it had
reached its full size.
--
"It is written in mathematical language"
Remove spam and invalid from address to reply.