Earth Meets Moon
The Earth and Moon are in a relationship just as two people might be in a relationship. We call this the Earth-Moon system. The Earth didn’t just meet the Moon one day, propose and then enter into a permanent relationship. There was, in essence, a courtship as the Earth “danced” with the Moon over time and eventually captured her.
How might capture have happened?
The Moon was in an orbit similar to that of the Earth. There were several gravitational interactions with some energy dissipated each time. The Moon and Earth developed a resonance or pattern. A resonance is a whole number ratio such as Pluto going around the Sun two times for every three times that Nepture orbits the Sun. In this case, the Earth probably went around the Sun once for every two times that the Moon orbited the Sun, always meeting back at the same point.
From this resonance, the Moon was captured into its current 28 day cycle. In order to make capture possible, we must understand that an energy sink needs to exist in order to dissipate energy from the Moon’s original heliocentric orbit. In the classic capture scenario of the Earth capturing the Moon in only a single interaction, a huge amount of energy would need to be dissipated. But, if the two were engaged in a “dance” with repeated interactions, far less energy would need to be lost. What would this “energy sink” look like? Could you see it at all or has it disappeared? The answer is evident everywhere and we are still experiencing this dissipation today throughout the Earth-Moon system.
The Model of Permian Tidal Heating
Both the Moon and Earth underwent significant change at what is recognized on Earth as the Permian Triassic (P-T) boundary. A modern capture model hypothesizes that capture brought the Moon near enough to the Earth to produce a secondary (tidal) heating event in the Earth-Moon system which can answer a multitude of the unexplained geophysical questions that exist in the Earth-Moon system.
Such an event would have provided the heat which initiated the formation of the lunar mare and Earth’s continental flood basalts beginning with the Siberian traps. This tidal heating correlated with the geologic history of Earth and impacts our understanding of plate tectonics and volcanism since the time known on Earth as the Permian.
The closer Moon would have caused mixing of the anoxic benthic layer with the oxygenated surface layer, of Earth’s Permian ocean, thus explaining a unique feature of the Permian marine extinction. Dissipation would have energized Earth’s tectonic system. The higher energy tectonic system would initiate the breakup of Pangaea and the spreading of the modern continents. The developing tectonic system would ultimately lead to the build up of atmospheric pressure during the Jurassic. This high density atmosphere allowed the dinosaurs to grow to their great size. As the tidal heating waned with the retreat of the Moon, the atmosphere thinned as less gas was being produced through volcanic activity associated with the energized tectonic system. During the Cretaceous period which ended with the disappearance of the dinosaur the beginning of seasonality can be seen in Earth’s climatic evolution for the first time.
The Moon has been slowly retreating from the Earth ever since the P-T boundary and the energy has been slowly dissipating. The seasonal Earth of today is a product of past tidal interactions between the Earth and Moon. Our modern Earth is a vital and dynamic body still reeling from a heating event that occurred in the not so distant past.