The Solar and Heliospheric Observatory, a joint mission between the European Space Agency and NASA, was not designed to find comets — its original goal was to study the Sun from its deep core to the outer layers of its atmosphere. But nearly 25 years since its launch, data from this space-based solar observatory has led to the discovery of well over half of all known comets — upwards of 3,950 new comets found. The huge number of SOHO-discovered comets comes thanks to a combination of well-designed instruments, a long lifespan, the hard work of citizen scientists and a little bit of luck.