Biomarkers in the atmosphere

A short-wavelength shield achieves protection of chemistry on the surface of the Earth or the initiation of chemistry in a prebiotic Earth or Titan. Essential it may be but there is an alternative - the photic zone. 

Radiative heating Scale height Chapman layers 

Structure of the planets that form around a local star 

Formation of a planet by accretion and the fractionation of the molten rock to form a metal core 

The capture of the moon by collision between the Earth and another large co-orbiting planetesimal with all of the consequences of a close moon larger tidal rise and fall 

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Barakat, A.O. (2002). PAHs and petroleum biomarkers in the atmospheric enviromnent of Alexandria City, Egypt. Water, Air and Soil Pollution, 139, 289-310. 

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