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• 1 2016-04-05T10:08:05+00:00 Composition of the solar system 9 plain 2019-12-29T14:53:58+00:00 There is another way in which we can examine the content of the solar system and that is by composition.  What was the mixture of elements from which the sun, the planets and well, us, were made?  Our sun consumes about 600 million tons of hydrogen per second, so we need lots of H to keep it going.  As we will see in module 5 we life forms are primarily composed of Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulfur so we need an adequate amount of that.  And we wander about on the rocky surface of a planet with an iron rich core which means we also needed those ingredients. If the solar system had not possessed the right mixture of ingredients, we would not exist in our current form.  So what is that mixture?
  
  The technical term that is used for this mixture is the “Cosmic abundance”.  It is beyond the scope of this course to elaborate how it comes about, but if you would like to learn more about abundance of the chemical elements, check here because it is actually a really fascinating story full of exploding stars. Most commonly this mixture is displayed as a relative abundance with increasing atomic number (the number of protons within the atoms nucelus) on one axis and a logarithmic scale (each tick is a factor of 10 more than the tick below it).  The reason for this presentation is that there are far more hydrogen and helium atoms than any other components in the solar system.  You will also notice that abundance generally decreases as atomic number increases.  There is relatively little of the heavier elements such as gold, which may be one of the reasons why we value this shiny yellow metal so much.  There is also a relatively significant spike in iron abundance and that explains why we have iron-rich cores within our terrestrial planets.
  
  If you prefer a representation of the cosmic abundance as a percentage-based bar graph, you may prefer this graph of a few select elements and their classification as elements.  In module 5 we will see that several elements are essential for the formation of life and these are identified as well in this figure.