Researchers have tried to conduct those tests for decades, but there's always been a problem. It is all too easy to contaminate the meteorite with amino acids from Earth, creating a bias in the results. Things changed during the spring 1995 semester, when Cronin taught a course in the ASU Honors College. He learned of an intriguing suggestion by William Bonner, an organic chemist at Stanford University, regarding neutron stars. Neutron stars are all that is left after a star has exploded in a supernova.
Neutron stars emit circular polarized light.
This means that the stars' light waves describe a narrow spiral as they travel. The light waves can spiral to the left or to the right. Left-handed organic compounds tend to absorb light waves spiraling in one direction. Right-handed compounds tend to absorb those spiraling in the other direction. Bonner and others had therefore proposed that circular polarized light emitted by a neutron star could have influenced molecular handedness in the great cloud of interstellar gas and dust from which the sun and its planets formed more than 4.5 billion years ago.