In this talk, I will present some of the activities performed during the commissioning phase of the Near Infrared Spectrometer and Photometer (NISP), one of the two scientific instruments aboard Euclid, following the launch of the satellite in July 2023. In particular, I will discuss the calibration of the sixteen infrared detectors composing the NISP focal plane, a crucial step to guarantee stable and reliable observations in space. I will also show how the NISP measurements can be exploited not only for observing distant galaxies, but also for monitoring the energetic particle environment surrounding the spacecraft. By analysing the signals produced by charged particles interacting with the detectors, we identified a clear correlation between Euclid measurements and Solar activity, especially during periods of enhanced Solar proton flux. These results highlight both the sensitivity of space telescopes to space weather and the importance of accurately identifying and monitoring spurious signals in astronomical observations.