Abundances of the chemical elements in the Solar System hinge, in part, on the way stars make the elements (or stellar nucleo-synthesis). This current model originated as a result of the atomic age.
Splitting the atom, and recognizing the processes within the hydrogen bomb, gave scientists the tools to understand processes in the Sun. Thus, in 1957, came the ground-breaking publication by Margaret Burbidge, Geoffrey Burbidge, William Fowler and Fred Hoyle in the journal Reviews of Modern Physics. (The theory would earn professor Fowler a Nobel in 1983 and ensured for the other authors a ‘rock-star status.’)
The theory explains, in no uncertain terms, how the chemical elements are synthesized in the stars. Thus the theory evolved (in the years since publication) as a fundamental work in the sciences.
Solar System Origins
When the Solar System came to be (4.5 billion years ago), the Universe was 10 billion years old. According to theory, stellar nucleo-synthesis created all of the elements which we currently know. Our stellar nursery (possibly 10-to-50 light years away) had just ejected the pre-solar system elements an energetic mass of proto-stellar dust and gas.
The elements comprising the Solar System (consisting of carbon, hydrogen, helium, oxygen, silicon, sulfur, nitrogen, iron, calcium, phosphorus and heavier elements) were then compressed into what is now the Sun and planets. The process of Solar System birth influenced how the chemical elements and their compounds would be distributed throughout the Solar System.
A primary influencer was – and still is – the temperature (or the current placement of life from the Sun). Ultimately, the role of temperature affects how and where liquid water would be found and the type of atmosphere found on a planet. The four inner planets: Mercury, Venus, Earth and Mars, are ‘terrestrial’ planets and contain (with the exception of Venus) water or ice. Each has an atmosphere that has evolved from its earliest times.
On the Earth, oxygen is present is present in one of two forms: compounded with other elements (H2O, CO2, NO2 and other elements), or in molecular form O2. However, the Earth’s atmosphere changes in an on-going process; one that is complex and that is fraught in ongoing experimentation, simulation and reality.
Early Earth: Developing the Atmosphere
Imagine our Earth in its early stages of development; the early Earth possessed a reduced atmosphere (or very little oxygen) at first. The early organisms of Earth may have utilized hydrogen gas or methane gas as a source of ‘respiration.’ Using that notion of early life, the ’bio-molecular machinery,’ may have been radically different, and the spark that enabled our evolution is shrouded behind experimentation and speculation.
What we do know is that, in part, oxygen became dominant for life due to the process of photosynthesis. Research findings, at this point, speculate upon the reasons for photosynthesis.
The fodder for speculation lies in the ‘whys’ for the process—from a reducing atmosphere to an oxygen-rich atmosphere. Was there a sudden and catastrophic asteroid or comet impact? Did the temperature of the planet rise to the point where ‘natural evolutionary processes’ aided in the establishment of photosynthesis?
Life and Universal Elements: Bio-chemical Origins and Ongoing Questions
Traces of an impact or evolutionary processes seem difficult to pin-down currently. However, the processes of life may occur elsewhere in Universe, independently of outside processes. It is our unwillingness to accept the truths at face-value that guides further research into our bio-chemical origins.