Distribution of fireball and comet orbits in the semi-major axis versus eccentricity space, highlighting the classification according to Tancredi (2014) criteria. The data points are: black dots: meteoroids in orbits not similar to cometary orbits, green dots: meteoroids inside resonances, blue dots: meteoroids in Jupiter family orbits, magenta squares: comets in Centaur-type orbits, and red squares: Jupiter family comets. Several relevant lines are drawn.