As the solar wind bombards the surface of our Moon, it embeds fragments of the raw stuff of the
Sun into particles of metal in the lunar soil. Some soil was brought back by the Apollo missions. By analysing these tiny particles with an ion microprobe, we can measure the proportions they hold of the two rare types of elemental oxygen. These proportions are different between the asteroids and the rocky planets. Will this measurement from the primordial source, the
Sun, be able to change our understanding of how the planets formed? With
Trevor Ireland of the
Research School of Earth Sciences, I analysed samples of lunar soil returned by the Apollo missions.