a)
Our solar system took a long time to form, 4.6 billion years ago. Our system formed just like all the other systems in the universe, from a nebula. A nebula is a cloud of gas/dust gives birth to stars. As a nebula collapses on itself, from a disturbance like a supernova explosion, it begins to heat up in the center and compress, this takes about 100,000 years (1, 2). After this it begins to cool slightly and form a star (1). As the energy begins to cool around it partials, like rocks and ice, start to revolve around the star. The partials begin to collide to form larger partials some the size of boulders or asteroids (1). Some of these boulders are big enough to have a gravitational pull and begin to pull particles in by toward it, making it bigger (1). This takes about 100 million years after the nebula has cooled, then another 100 million to form into around 10 or so planets revolving around a star (1).
b)
Many events let to the creation of the earth we know today. Earth formed roughly 4.57 billion years ago, this was also about the time our moon formed (3). Then about 3.9-2.5 simple life forms like bacteria and algae began to form on Earth, releasing oxygen into our atmosphere (4). Oxygen continued to build in our atmosphere and more life forms began to form (2.5 million to .5 million) (4).
c)
Index Fossils can be used to determine time sequences. Depending on the layer of the rock and the rock/fossil observed they can determine the age of the fossil and other things about earth’s history (5, 6). The farther down in the earth’s crust the fossil/rock is the older the fossils is (5).
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