The radioactive element astatine, the name of which is derived from the Greek word for 'instability,' is so rare on Earth that it has not yet been investigated to any greater extent and, as a consequence, very little is known about it. Using artificially generated astatine, a physicist has now managed for the first time to experimentally explore one of its fundamental parameters, the ionization potential, and thus determine one of the most important properties of the rare element.