UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS

When walking or driving somewhere new most people would take a map or a GPS device to find their way around. Planetary scientists usually make maps of the surfaces of planetary bodies to understand surface features. For the most part, the magnetospheres (space environments) of the planets are invisible. We have to use instruments that detect particles and magnetic fields to find our way around, like using senses of taste, smell and touch to understand where we are inside a magnetosphere.

Dione is a moon of Saturn, discovered in 1684 by the Italian astronomer Giovanni Cassini. Over 300 years later, planetary scientists including Andrew Coates and Geraint Jones from MSSL-UCL, have discovered that Dione has a weak exosphere near its surface (at planets with denser atmospheres, the exosphere is the outermost layer of its atmosphere). This exosphere is very very thin, about a million billionth of the Earth's atmospheric density. The work shows that the exosphere contains molecular oxygen - the same form of oxygen as in Earth's atmosphere. This gives us important information about how the atmosphere is produced.