Lunar Capture

Origins of the Earth's Moon


Two hundred and fifty million years ago at a time known as the Permian Extinction (Permian-Triassic Boundary), a devastating event struck Earth. This event caused some 90% of Earth’s species and perhaps 95% of all marine species to go extinct (1). It appears that a variety of things combined to “cause” the Permian extinction. The central event, however, was a massive volcanic eruption which pumped huge quantities of flood basalts onto the Earth’s surface. This volcanic episode is known today as the Siberian traps. The formation of the Siberian traps put massive quantities of pollutants into the atmosphere and oceans, compromising most environments on Earth. In a very short time, and for millions of years to come, life on Earth struggled to survive.

It is apparent that the Siberian Traps played a pivotal role in the Permian Extinction. But what drove this very energetic eruption and why did life struggle for so long afterwards? The answers may lie beyond the Earth itself.

The Earth and Moon actually form a binary pair, in other words, a dual planetary system. When the Earth is thought of not as a single planet, but as part of a system, it is possible to produce a model which can explain the Permian Extinction and its aftermath. The Close Approach Lunar Model (CALM) proposes that the Moon’s original orbit, which was expanding originally, eventually through dissipation of heat and/or a large impacts, was slowed and began to spiral back in towards the Earth. As the Moon’s orbit then began to decay inwards the moon reached a point when it approached the Earth for a very close, short, and energetic time, only to be repelled (44) out again to its present position. This close approach triggered tidal heating on the Earth, producing the Siberian Traps. It also caused mixing of a preexisting two layer ocean, increased tidal erosion, and strong tidal surges. All of these features are important factors in the Permian Extinction event. In addition, some of the Earth’s atmosphere was stripped away, increasing life’s exposure to the radiation of space. With the thinning protection of the shielding atmosphere, life on Earth struggled on the brink of extinction for nearly 5 million years.

As life began to rebound, a new world was forming. The CALM postulates that most of the energy of the Moon’s approach was dissipated as heat into the Earth’s interior. This stored heat manifested itself through the re-energization of plate tectonics, beginning in the Triassic, which ultimately lead to the runaway green house scenario of the Jurassic period. The heat produced by the Moon’s close approach worked steadily over the next 250 million years to transform the physical shape of the Earth’s continental landmasses. The history of life on Earth reflects to this day the slowly dissipating energy left from the event of near lunar approach at what is the Permian-Triassic Boundary.