Saturday, February 11, 2006

Moon Nearly Split In Two 4 Billion Years Ago

By Elaine Meinel Supkis

The great lava flows that discolor the surface of the moon that faces the earth was the super lava flow from a single impact that tore nearly through the moon, permanently deforming both the back by depressing it and the front with a big bulge.

Planetary scientists have found the remains of ancient lunar impacts that may have helped create the surface feature commonly known as the "Man in the Moon."

Findings by a team at Ohio State University suggest that a large object actually hit the far side of the moon about 4 billion years ago, and it sent a shock wave through the Moon's core and all the way to the Earth-facing side. When the crust recoiled, the Moon's surface displayed the markings of the encounter.
Many mysteries of the moon are being probed by unmanned missions. One of the more interesting probes mapped the gravity fields on the moon and came up with some surprises.

Click here for the NASA data which I used for my schematic drawing.
Unfortunately, the article I cited here from Space isn't all that informative so I decided to hazard some guesses here. The gravity hole that is roundest and biggest and I presume, deepest, is Mare Orientale. It also has quite a lava flow from it that is directional, namely, it poured out towards the South Pole.

On the other side of the moon lie the huge lava flows that make up the Mare complex there. If you look at the moon, there are no huge craters there, instead, all the earliest impact points are covered by a massive lava flow punctuated by a few random craters of much later origin. This lava flowed into some of the older craters made by large objects which is why they seem fragmented but it is probable that all the lava flow on the Near Side of the Moon comes from this singular impact.

Evidently, the mantle of the moon on the far side was shoved in so deep, a part of it penetrated deep into the core. If this object hitting the Moon was any larger, it possibly could have shattered the Moon. The Moon is much smaller than the earth so the ratio of objects hitting vs planetary surface makes the Moon much more vulnerable to damage. I wonder if Venus had a moon, too, but it was annihilated in the earliest years as tons of debrie fell back into the sun when the sun pulsed out a lot of the hard matter that it was born in, for we now know, all stars are born in the dark realms where all the dirt and dust and fairly large objects congregate. Once a star begins goes "nuclear" all the dirt surrounding it is shoved away.

Since a lot of this dirt was falling towards the sun when it hit us, I would suppose the closer to the sun an object was, the more it was hit by incoming debrie? We have pictures of Mercury and it is wall to all impact zones. It is amazing it remained intact, considering everything. Since the Moon orbits the earth, has it played the role of mine sweeper for us? Taking the brunt of the debrie coming in? One wonders.

Another oddity of our planet which might make it pretty hard to replicate! We are "lucky" on so many levels.

And I am glad we have a moon or we wouldn't have tides and it might have made life on earth harder to evolve since tides are a changable environment which means more solutions, more niches. Also, how else can women have menstral periods if we had no moon?

On the other hand, I hated those. Ick. Oh well, at least it looks pretty up there.

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