Jonathan Toner is a planetary geochemist who studies liquid water formation in extreme environments on Earth and beyond. Liquid water is essential for life-as-we-know-it, so understanding the formation and properties in extreme planetary environments tells us if life is possible there. Major planetary research sites of interest include Earth, Mars, Enceladus (a moon of Saturn), Europa (a moon of Jupiter), and Ceres. Jonathan uses several approaches to investigate salty water at extreme conditions. In the laboratory, he measures the properties and conditions under which water is possible. He also researches liquid water formation in planetary analog environments on Earth, such as the McMurdo Dry Valleys in Antarctica. Finally, it’d be hard to get to a place like Mars, so he uses numerical models to predict liquid water formation and associated minerals on planetary bodies.