“Miracle Planet: The Violent Past” Video Questions 1. Through what process is Ea
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Question
“Miracle Planet: The Violent Past” Video Questions 1. Through what process is Earth thought to have grown to its present size? 2. Why doesn’t Mars still hold water or an atmosphere? Why does Earth? 3. How are bacteria found in salt crystals from Permian salt lake deposits in the SW-US linked to the survival of early life on Earth? 4. If the Earth’s surface was continually heated during the Archean Eon, then what is a plausible explanation for archaea found in rocks dated as 3.8 Ga? By what mechanism could life have survived? 5. What is the significance of the anaerobic bacteria found in the water-covered rocks deep within mine shafts of South Africa?
Explanation / Answer
In accordance with Chegg policy I am answering the first question kindly ask other as separate question
1) Early Earth was a very different place to the planet we inhabit today. Initially the planet didn't have a crust, mantle and core, and instead all the elements were evenly mixed. There were no oceans nor continents and no atmosphere. Meteorite collisions, radioactive decay and planetary compression made Earth become hotter and hotter. After a few hundred million years the temperature of Earth reached 2,000C - the melting point of iron - and Earth's core was formed.
At this point much of the Earth was molten and there may have been a magma ocean at the surface. Gradually the Earth cooled and the planet settled out into a core, mantle and crust. This layering of the planet helped to trigger plate tectonics at the surface, and the Earth began to look a little more like the planet we know today.
Most geologists think Earth's atmosphere and oceans arrived about 4bn years ago - the product of multiple volcanic burps. Alternatively, they may have come from comets colliding with Earth and releasing water and gases at the surface.
Earth's early atmosphere didn't contain much oxygen and was very different to the one we have today. Nonetheless, the atmosphere and oceans enabled life to get a foothold, and the first single-celled organisms evolved about 4bn years ago.
Gradually these algae changed the composition of Earth's atmosphere, munching their way through carbon dioxide and water, and releasing oxygen. By about 2.5bn years ago significant amounts of oxygen had built up in Earth's atmosphere. The scene was set for complex life to evolve.
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