Euclid uses a method called 'step-and-stare to scan the night sky, which allows it to combine a bunch of separate measurements to form a larger image. Ultimately, scientists believe this will yield the largest cosmological survey ever conducted in visible and near-infrared light. [Euclid faces some setbacks during commissioning](https://www.space.com/euclid-guidance-light-sensor-setbacks-commissioning-dark-universe) Credit: ESA. Acknowledgement: Work performed by ATG under contract for ESA.