We present a comprehensive study of the nightside discrete electron aurora phenomenon on Mars, utilizing observations from EMUS onboard EMM. The oxygen emission at 130.4 nm is by far the brightest FUV auroral emission line observed at Mars. We identify auroral pixels in OI 130.4 nm disk observations, with higher sensitivity than previously possible. Our statistical analysis reveals regional, SZA, local time, and seasonal dependencies of auroral occurrence. Higher occurrence of aurora is observed in regions of open magnetic topology and vertical crustal magnetic fields. Aurora occurs more frequently closer to the terminator and is more likely on the dusk versus dawn sides of the night hemisphere. A pronounced auroral feature appears close to midnight local times in the southern hemisphere, consistent with the “spot” of energetic electron fluxes previously identified in the MGS data. The auroral spot is more frequent after midnight than before. Additionally, some regions on Mars are “aurora voids” where essentially no aurora occurs. The non-crustal field aurora exhibits a seasonal dependence, with major enhancements around Ls 235° (near perihelion) and Ls 30°. This is in line with the seasonal variability in ionospheric TEC observed by Mars Express, which is in turn related to the variability of solar irradiance and thermospheric density. Aurora occurrence also shows an increase with the rise of Solar Cycle 25. These observations not only shed light on where and when Martian aurora occurs, but also add to our understanding of Mars’ magnetic environment and its interaction with the heliospheric environment.