Although we weren’t here to observe the birth of our own solar system, astronomers have developed a relatively informed picture of how it likely happened, based on observations of our present-day home and the infant planets forming around other stars. But every so often, something throws a wrench in our theories, and that may have just happened — researchers have discovered interesting new properties of Saturn and its moons that contradict our current models for how the solar system formed.
In a paper accepted November 28 to the journal Icarus, researchers from the Planetary Science Institute, the University of Arizona, NASA Ames Research Center, and the U.S. Geological survey report their measurements of isotope ratios in the Saturn system. Isotopes are atoms of a single element with the same number of protons and electrons, but differing numbers of neutrons. Studying the abundance of certain isotopes helps astronomers piece together an object’s history. Some isotopes were more or less common, particularly in certain areas of the solar nebula as it formed planets; others are more likely to stick around or appear after processes such as heating or evaporation. These researchers found that, based on spectroscopic observations of the Saturn system from Cassini, the water in Saturn’s rings and moons is surprisingly like the water on Earth — an unexpected result, given their disparate locations. Even stranger, the water on Saturn’s moon Phoebe (and only Phoebe) is unlike the rest of the water in the Saturn system, suggesting it formed even farther out in the solar nebula, rather than in place around the ringed planet.
