Software
I have worked with and developed different scientific software suites to interpret observed astronomical data and generate theoretical models that describe the life of a (variable) star that vibrates in its natural frequencies. Such vibrations/oscillations cause the star to periodically dim and brighten, which can be observed in astronomical data products, such as the photometric light curves (of specific variable stars) that I have studied in my doctoral dissertation - these were observed by the NASA Kepler space telescope.
Writing (research) software is one of my passions, and I regularly like to challenge myself to learn more about different (typically astrophysical) software suites/different programming languages.
If you share this passion and want to develop your own (research) software, I highly recommend reading and applying the FAIR (Findable, Accessible, Interoperable and Reusable) principles for Research Software (FAIR4RS principles, which are described in this Nature publication).