How are solar system abundances used in cosmochemistry

We have now considered how the solar system abundances are determined and have discussed the uncertainties in the abundance numbers. Here we briefly discuss how these abundances are used in cosmochemistry. These uses will be discussed further in later chapters. 

The oxygen isotopic composition of the solar system is a key constraint for understanding the environment in which the Sun formed, the environment in the early solar system, and the processes that operated in the early solar system. Oxygen isotopic composition is also a key property by which we classify meteorites. Yet until very recently, we have not been able to make any measurement that could unambiguously tell us what the oxygen isotopic composition of the Sun, and by extension the solar system, really is. 

In this chapter, we have introduced solar system abundances and cosmic abundances of the elements and isotopes and briefly discussed their importance in cosmochemistry. The idea of cosmic abundances has been around for over a century and is rooted in measurements of many different celestial objects. Only in the last 20-30 years has our knowledge of the compositions of the solar system, of stars and molecular clouds in our galaxy, and of other galaxies grown sufficiently that we can now detect clear compositional differences between our solar system and other objects in the galaxy and the universe. 

Solar system abundances are a cornerstone of our understanding of the origin and evolution of the solar system and the elements from which it formed. To understand 

In the next few chapters, we will investigate these topics further. For example, in Chapter 5, we will introduce presolar grains and show how they can be used to investigate stellar nucleosynthesis and processes operating in interstellar space and in the early solar system, and in Chapter 7, we will discuss chemical and isotopic fractionation processes that operate in the solar system. 

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