Theories are a collection of scientific data that is generally accepted and reproducible. Theories are a result from several repeated experiments, but theories are not based on a single hypothesis. Several hypotheses are tested and appraised to become a well accepted theory. Theories may also be revised over time and can predict what may happen in the future. On the other hand, theories are not proven facts.
Mars is just a fraction the size of the Earth, so it cooled more rapidly. And as it cooled, its molten iron core hardened. As a result, Mars stopped generating its magnetic shield. And, according to one theory, this left its atmosphere to be scoured away by the solar wind.
Basically the first part is when the Euglena starts swimming to the light direction.
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In the mantle/////////////////////////////////
The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere. Carbon is released back into the atmosphere when organisms die, volcanoes erupt, fires blaze, fossil fuels are burned, and through a variety of other mechanisms.