Cometary origin of carbon, nitrogen and water on the Earth

Two independent assumptions are substantiated; firstly, that the Earth accreted from dust particles that were hot enough not to contain any volatiles; secondly, that after the accretion was finished, all the volatiles of the biosphere, including the atmosphere and the oceans, were brought by a cometary bombardment.The first assumption is based on the empirical evidence that the planets originated from minor bodies. These minor bodies were generated by accumulation of fine dust particles, which sedimented from the gas of the solar nebula. We will demonstrate that, when the particles from the Earth's zone were separated from the nebular gas, they were close to 1000 K and at a thermochemical equilibrium with this gas. This implies that almost all carbon, nitrogen and water remained in the gas phase, respectively as CO, N2 and steam. Since there was no volatile left in the minor bodies, they could produce neither atmosphere nor oceans.The second assumption is based on the existence of the giant planets in the outer reaches of the solar system. Over there the solar nebula was very cold; the minor bodies were generated by accumulation of frosty particles and became cometary nuclei containing a large amount of ice and volatile stuff. When the giant planets' embryos reached a mass of 10 to 20 terrestrial masses, the orbits of billions of minor icy bodies were perturbed enough to send some of them to the inner solar system. A model shows that the icy bodies which hit the Earth are more than enough to explain the whole biosphere, including the atmosphere and the oceans.