Meteorites

In 1969, the Murchison meteorite fell in rural Australia; pieces of the meteorite were collected very soon after it fell, limiting terrestrial contamination.

http://www.astrosurf.com/lombry/Images/meteorite-murchison.jpg

Murchison is a carbonaceous chondrite meteorite -- it has lots of carbon in it. In fact, it also has amino acids!

Amino acids in most carbonaceous chondrites are racemic (remind yourself what this means).

However, the amino acids in Murchison are not found to be racemic, but rather dominated by the left-handed form. Recall that life on Earth uses exclusively left-handed amino acids!

There are at least two different implications of this:

  • This might be additional evidence for the possibility that either life or the complex building blocks necessary for life were delivered to the early Earth, rather than formed here; or
  • Conditions in the early Solar System may have been conducive to producing left-handed amino acids, for example from polarized light from the young Sun.

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