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This is Chapter 7, Creation of the Universe, of the outline of a book that I plan to write on Progressive Creation.
There were three main theories on the origin of the Moon: it formed in place, it formed elsewhere and then was captured, and it was ejected from Earth (Ward & Brownlee, pp.229- 230; Whitehouse, 2001, pp.238-239). The most popular theory was the first, that the Moon had formed cold and grew by accretion (Ward & Brownlee, p.229; Whitehouse, 2001, p.239). However, in 1969, Apollo 11 returned lunar surface rocks which indicated that the Moon had a highly improbable origin (Ward & Brownlee, p.229), that no one had thought of (Whitehouse, 2001, pp.239-240; Whitehouse, 2001, pp.239-240). These moon rocks lacked volatile elements, which vapourise when heated (Whitehouse, 2001, pp.241). They contained an over-abundance of sideophile, or `iron-loving', elemnts (Whitehouse, 2001, pp.241). Indeed, the lunar rocks were similar in composition to the Earth's mantle (Whitehouse, 2001, pp.241).
Eventually it was realised in 1984, after computers simulations that the formed by an impact by a Mars-sized planet with the newly forming Earth (Ward & Brownlee, p.230; Ross, 1998, p.32; Whitehouse, 2001, p.245-). This impactor also had a rocky crust and an iron core like Earth (Whitehouse, 2001, pp.246,251-254). When the two planets collided, their metallic cores coalesced to form Earth's core while portions of the mantles of both bodies was ejected into orbit and aggregated to form the Moon (Ward & Brownlee, p.231; Whitehouse, 2001, p.250). The Moon then spiralled outward which it continues to do (Ward & Brownlee, p.231; Whitehouse, 2001, p.25).
This single event, blew away Earth original opaque, toxic atmosphere, increased the mass of the Earth enough to retain by gravity a large quantity of water vapor, and it stabilised the tilt of Earth's axis (Ross, 1998, p.32; Ward & Brownlee, p.234; Whitehouse, 2001, p.257). In order to produce such a massive moon, the impacting body had to be the right size, the right composition, it had to impact at the right point on Earth, and the impact had to have occurred at just the right time in Earth's growth (Ward & Brownlee, p.230; Ross, 1998, p.32; Whitehouse, 2001, p.246).
So the Earth we now live on is Earth Mk. II, Earth Mk. I being a much smaller and different world that we could never have lived on (Whitehouse, 2001, pp.237,244). And having a large moon may be a key characteristic necessary for a life-permitting Earth-like planet (Ward & Brownlee, p.234; Whitehouse, 2001, p.257). Without the impact driving a lot of water off permanently into space, sea level may have been thousands of metres higher than it is, with little, if any dry land (Whitehouse, 2001, p.259). In addition, the Moon may have deflected or intercepted asteroids that otherwise would have collided with Earth and changed the course of life's history (Whitehouse, 2001, p.258). [top]
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Created: 8 August, 2003. Updated: 10 February, 2005.