“The rebreathing of our exhaled air will without a doubt create oxygen deficiency and a flooding of carbon dioxide. We know that the human brain is very sensitive to oxygen deprivation. There are nerve cells for example in the hippocampus, that can’t be longer than 3 minutes without oxygen – they cannot survive. The acute warning symptoms are headaches, drowsiness, dizziness, issues in concentration, slowing down of the reaction time – reactions of the cognitive system.
Small clumps of debris gathered into larger clumps, which merged into small planets, which then collided to form larger planets.
Scientists estimate that Earth suffered around 10 of these giant collisions. Each altered the tilt of the Earth by knocking it one direction or the other. In the last of these encounters, a rocky orb roughly the size of Mars smashed into the Earth.
… Hamilton said that scientists may spar over the details of the collision, but they broadly agree on what happened next. The Mars-sized planet hit the Earth at such an angle and with such force that it sent pieces of both celestial bodies flying into space. That debris settled into orbit around the Earth and eventually coalesced into the moon.