Delsemme A H
Department of Physics and Astronomy, The University of Toledo, OH 43606, USA.
Adv Space Res. 1995 Mar;15(3):49-57. doi: 10.1016/s0273-1177(99)80063-5.
Empirical evidence of the accretion temperature for undifferentiated meteorites coming from the asteroid belt, combined with any reasonable temperature gradient extending from the asteroid belt to the Earth's zone, suggests that the Earth accreted from very hot dust grains that were degassed from all volatile elements and depleted in labile compounds. Isotopic evidence from the atmospheric noble gases also shows that no primary atmosphere has survived on the Earth. The only possible source for the atmosphere and the oceans is therefore the cometary bombardment that is predicted as the inescapable consequence of the formation of the giant planets. This implies that comets are the only source of organic carbon, nitrogen and water, hence of the total biosphere of the Earth.
来自小行星带的未分化陨石吸积温度的经验证据，结合从小行星带延伸到地球区域的任何合理温度梯度，表明地球是由非常热的尘埃颗粒吸积形成的，这些尘埃颗粒已从所有挥发性元素中脱气，并贫化了不稳定化合物。来自大气惰性气体的同位素证据也表明，地球上没有原始大气留存下来。因此，大气和海洋的唯一可能来源是彗星撞击，这被预测为巨行星形成不可避免的结果。这意味着彗星是有机碳、氮和水的唯一来源，因此也是地球整个生物圈的唯一来源。
