For centuries, mankind has peered into the heavens at our
moon and wondered where it came from, how it came to orbit
around the Earth, what it is made of, and why there are so
many similarities and differences in the earth and
the moon's composition.
The Earth's moon is unusually close to the Earth and is a key
to life on our planet.
It governs the oceans tide cycles, which may have been
necessary to prepare for the first stages of Life in oceans.
But it's origin has been the subject of a number of
different theories.
The current leading theory is that a planetoid about the size
of Mars smashed into the Earth some four and a half billion
years ago, blasting off a chunk of the early, still developing
Earth.
And the remains of both planets came together to form the moon.
This has become known as the giant impact Theory.
Astrogeologist have recently come closer to proving the
theory by a scientific examination of Earth.
And lunar rocks brought back by the Apollo missions.
Evidence is suggesting that even life on Earth may not have
been possible without a cataclysmic event.
Early in the Earth's history,
giant cataclysmic impacts are not new to our solar system.
It is generally thought that the planet Uranus, which is
tilted on its side, got that way as a result of at least one
impact maybe to buy a planet-sized object in its
history.
Other planets in our solar system have also shown signs of
gigantic impacts.
The planet Venus has been the subject of such collisions.
Venus, however, doesn't have a moon like ours.
So the question arises, why not?
If Venus suffered such a similar impact as Earth, why
doesn't it have a moon to?
There are several scientific explanations for this, which
include experiments on how large the Rogue Planet would
have to have been
at what speed it was traveling when it impacted at what angle
did it in act.
What effects did Gravity have on the remnants of the impact?
Perhaps there was a second impact, or maybe a newly
forming Moon, simply spiraled back into the planet.
Such occurrences were common during the early formation of
our solar system.
These questions apply to the Earth to when trying to
determine what kind of impact would have been large enough to
produce enough debris to form the moon without destroying the
Earth completely, and also destroying the Rogue Planet
Thea at the same time.
The Earth was subjected to dozens of such collisions
during its formation.
The planets in our solar system were created by collisions
between small dwarf planets orbiting the newborn son.
These collisions cause smaller planets to melt together and
form larger and larger planets.
One theory is that the Earth and the moon were created at
the same time as a result of a collision between two of the
larger form planets.
The Rogue Planet, which is thought to have impacted with
the Earth, was named theia after the mythical Greek Titan
Thea who gave birth to the Moon.
Goddess saline.
According to the giant impact Theory, there were many more
planetoids other than Earth orbiting around our sun.
During the solar systems development.
Theo, which is believed to have been the size of Mars, is
thought to have formed at the same time as the Earth and
orbited our son to Thea grew larger, however, making its
orbit unstable, and eventually it collided with the Earth.
In the last days of Planet formation, a body as big as
Pluto probably also smashed into Earth after the planet had
been clobbered by Thea.
Some theorists suggest that this is what could have knocked
the Earth off its axis this by 10 degrees where it is today.
Thea is thought to have struck the Earth at an oblique angle
of about 45 degrees.
When the Earth was nearly fully formed,
a significant amount of mantle material from both planets
would have been ejected into orbit around the Earth.
It is estimated that about 20% of Thea's Mass would have ended
up as debris orbiting the Earth.
And about half of this would have coalesced into the moon.
Scientists are trying to determine ermine if this
Collision was a big Splat, where the Rogue Planet simply
merged with the Earth on impact ejecting enough debris to form
the moon, or whether it was a hit-and-run where a sizable
chunk of the earth and part of the Rogue planet formed
the moon.
And the Rogue Planet continued on its way still out there
somewhere.
The moon at that time was thought to have been very close
to the Earth.
It would have appeared 15 times as large as it does today, and
would have had four thousand times the pull on the earth.
And it does now.
It began moving away from the earth and continues to do so
today,
launched in 2008 NASA's stereo solar Observatory probes flank
the sun on opposite sides.
They are entering an area where they will be able to search for
any remnants of Thea, which may still be orbiting inside our
solar system.
Did Thea survive its impact with Earth?
If Theo collided directly with Earth, instead of barely
swiping it in the Collision, speed was higher than
originally assumed the mm a have been totally destroyed.
If, however, Thea was larger than Mars hit the Earth with a
glancing slower motion blow and simply tore off material that
formed the Moon,
it would have survived this hit-and-run and went on its way.
Is there then on its way to Interstellar space, never to
return?
Or was Thea sent into a trajectory that would
eventually bring it back into our solar system for another
encounter with the Earth?