Planetary geologists have measured the relative quantities of oxygen isotopes in samples from the Earth, the Moon, Mars, and meteorites, but were long unable to obtain reference values for the isotope ratios in the Sun, believed to be the same as those of the primordial solar nebula.
Planetgeologer har målt den relative oxygenisotop-mængde i prøver fra Jorden, Månen, Mars og meteoritter, men har ikke kunnet skaffe referenceværdier for isotopforholdene i Solen, der menes at være det samme som i den oprindelige soltåge.