Space Forum / Astronomy / July 2008

Selene having once impacted Earth, and obviously having survived that
encounter as a captured binary planet, is like most all moons of
Jupiter are captured by means other than directly interacting with the
hidden surface of Jupiter.  Perhaps Jupiter itself is the merger or
combining of two or three significants planets, whereas all sorts of
secondary stuff most likely got created.

This is not simple physics that can be so easily roughed out on the
back of some used envelope.

Public owned supercomputers and their fully interactive 3D orbital
simulators as based entirely upon the regular laws of physics can
accomplish these complex encounters, such as an icy Selene
lithobraking itself by way of surviving a glancing blow off mother
Earth which was also rather icy at the time.  To such encounters,
Earth is 98.5% fluid.

Saul and other disinformation spewing DARPA spooks and moles know this
is true.  Their pretend-atheism of being Zionist/Nazis cloaked as
something other, is proof positive in of itself that we're being
continually lied to by those in charge of our private parts.

Brad Guth Brad_Guth Brad.Guth BradGuth

Maybe it was a combination of two of these ideas?

When the planets were but protoplanets, it wouldn't
have taken a Mars-sized object to collide with the
debris that would become Earth and Moon to result
in our double-planet system.  There were a whole lot
of objects in weird trajectories back then, and even a
fairly small asteriod or comet could have caused some
material to be ejected from protoEarth.

Here is where this idea breaks off into two possible
events, both very similar.  If the early NEO (near-
Earth object) came from the direction of the Sun, then
the debris that broke off and became planet Selene
probably would have headed out into a slightly larger
orbit than Earth's orbit, a bit farther from the Sun.  If
the NEO came from the other direction, heading in the
general direction of the Sun, then the protoSelene
materials would have probably been pushed into an
orbit that was just a bit nearer to the Sun than Earth's
orbit.

Whichever way this happened, the collision would have
had to be forceful enough to send the protoSelene dust
far enough away so that the Sun's gravitational impact
on Selene would be much stronger than protoEarth's
impact.

Now, if protoSelene had been sent to an orbit farther
from the Sun than protoEarth (this was the most likely
event as you'll see in a minute), the protoEarth debris
would be going a bit faster than the protoSelene dust.
Since protoEarth's speed was just a little bit faster
than protoSelene's speed, it would have taken many,
many, many revolutions of the two protoplanets going
around the Sun before Earth would catch back up to
Selene.

And if Selene was sent to an orbit just a bit inferior to
Earth's orbit (just a bit closer to the Sun), then Selene
would have been traveling a bit faster than Earth. And
it would have taken a lot of orbits around the Sun for
Selene to finally get all the way back around and catch
up to Earth.

I think it's a little bit more likely that the colliding NEO
came from the direction of the Sun and split off the
Selene material from protoEarth to an orbit that was
farther from the Sun.  Here's why...

If Earth was a little closer to the Sun, then when Earth
finally came back around to catch up to Selene, the
Sun's gravitational influence would add to Earth's and
help Earth capture Selene.  Of course, depending on
how far away from Earth planet Selene actually was
(at its nearest approach) it may have taken the Earth
several "near misses" before finally capturing Selene.
And each time the Sun would help Earth bring Selene
a little closer to Earth.

And if Selene had been in an orbit that was closer to
the Sun, Earth's gravitational influence would probably
lose the tug of war with the Sun, and Selene might
still be out there in its own "near-Earth orbit" orbit
around the Sun.  So Selene's orbit was probably a bit
farther from the Sun than Earth's orbit.

Eventually, the faster Earth caught up to a Selene that
was near enough to capture.  The speeds of Earth and
Selene would not have been all that different, and the
capture would have been fairly smooth.  This would
account for 1) the near-circular orbit of Selene around
the Earth, 2) the fact that Selene appears to be made
mostly of mantle-type materials with very little iron or
other Earth core materials, and 3) the nearness of the
orbit of Selene to the ecliptic and how far away its
orbit is from Earth's equatorial plane.

In light of this, it might be more correct to say that the
Earth and Moon "captured each other".  It would have
been much like a man and woman dancing.  The
woman dances in toward the man, who "captures" her
and then the two begin to spin around, the man more
or less in place while the lady "revolves" around a
common center of gravity that lies slightly within the
man's chest.

So this proposal of "Moon origin" uses the "collision
theory", although not a collision with a Mars-sized orb,
but rather a smaller object, that dispersed the outer
material of protoEarth into a near orbit.  And the
dispersed debris accreted/coalesced to become planet
Selene.

In addition, this proposal also uses the "capture theory",
although not the type of capture one usually pictures in
one's mind.  Instead of a capture from some wild-angle
trajectory, which would be impossible given Selene's
large mass and the nearness to a circle of its orbit
around the Earth, a capture from a "near-Earth-orbit"
orbit would have been not only possible, but very likely
(as long as Selene hadn't been pushed to an orbit that
was too far away from Earth's orbit).

The NEO that originally collided with protoEarth would
have had to be on a trajectory that was very near to
the ecliptic to make the Selene debris coalesce so near
to the ecliptic.  But that's not too much of a stretch,
because back then, it's likely that the vast majority of
rogue objects that could have collided with Earth and
the others that left craters on Selene were probably
also part of the original accretion disk and would have
naturally orbited the Sun on or near the ecliptic.  This
NEO would have been large enough to do what i have
described, and yet not so large that it would disturb
protoEarth's near-circular orbit around the Sun.

So what do ya think, Bert... 2 out of 3?  I don't like the
idea of protoEarth and protoSelene emerging as whorls
very near each other.  This idea would seem to lead to
Selene having core materials much more similar to
Earth's core, more iron and such.

So down with the double-whorl idea and up with both
the collision and capture ideas, with the differences i
noted, of course.

To give credit where credit is due, let me note here
that it was Ralph Hertle who, here in alt.astronomy,
first voiced the idea of Earth and Moon forming into
orbits that were near each other, and then eventually
they captured each other to share a common, stable
barycenter orbit around the Sun.

happy days and...
  starry starry nights!

$2 a can?  The bar I go to charges $3.50 a bottle for Bud Light!

Gas is still under $4 a gallon.

Saul Levy

Cactus Saul  You did not have to shout out that I'm an alcoholic. People
think alcoholic are drunks. Stager slur their words fall down. Oooops a
thought just jumped in I am a ALCOHOLIC   Bert