BIO 200 Lecture 2: Lecture 2a Notes - The History of Earth
25 Sep 2016
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Large rotating cloud of dust, rocks, and gas that existed prior to the formation of. Predominately composed of hydrogen and helium produced in the big bang, as well as heavier elements ejected by supernovas a. iii. 4. 6 billion years ago nearby star was destroyed in a supernova a. iii. 1. Most of the mass inside the disk became concentrated in the middle and began to heat up a. iii. 3. This heat led to nuclear fusion of hydrogen into helium a. iii. 3. a. Led to the formation of the sun a. iv. Meanwhile, perturbations caused by the collision of matter remained in the disk a. iv. 1. As gravity caused matter to condense, the rest of the protoplanetary area began separating into rings a. iv. 3. Successively larger fragments began colliding together and became larger objects destined to become planets a. iv. 4. Earth emerged as the protoplanets approximately 150km from the new sun a. iv. 4. a. Earth took 10-20 million years to complete (approx.
