Point-like cosmic-ray density in VIS during a low M-class solar flare. The cosmic rays are caused by X-rays impinging onto the detectors after penetrating Euclid’s sunshield in some gaps between the solar cells, causing characteristic geometric patterns. During rare but bright X-class flares, up to 25% of the VIS detector area must be masked. The location of the pattern and its shape depends strongly on the LoS of VIS towards the Sun through the sunshield, and thus on the spacecraft’s attitude.