IBEX: Observing the Sun's Horizon

The Interstellar Boundary Explorer, or IBEX, is the first mission designed to map the entire region of the boundary of our Solar System. This region emits no light so, instead, IBEX measures the particles traveling inward from the boundary. IBEX's objective is to discover the nature of the interactions between the solar wind and the interstellar medium at the edge of our Solar System.