Italian researchers have packed up a new solar instrument, driven it carefully across the continent by road rather than risk it in an aircraft hold, and readied it for one of the more nerve-racking experiments in physics: a test that has to succeed on the first attempt, during the total solar eclipse that sweeps over Europe on 12 August. The device, called the Circular Slit Spectrometer, or CISS, will point at the Sun from the Javalambre Astrophysical Observatory in Spain, directly under the path of totality. The appeal of an eclipse is simple, and it is the reason these events remain such prized natural laboratories. CISS is not a coronagraph, the kind of instrument that manufactures its own eclipse by blocking the disc. Even as European scientists lean on a rare natural eclipse as a proving ground, Europe’s space agencies are busy engineering artificial ones.