Has human activity altered the mass of the Earth?

No. If you traced every atom of bone tissue and building material back to its source, it would always return you to materials extracted from the earth. The earth has not increased its mass because of the biosphere, human manufacturing, or other processes internal to the surface of this planet. It has, however, gained mass because every year millions of pounds of meteoritic material crashes into the atmosphere and ground. But compared to the 10^27 grams of mass of the Earth, even this fantastic rainfall from space is completely negligible!


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All answers are provided by Dr. Sten Odenwald (Raytheon STX) for the
NASA IMAGE/POETRY project.