De systemate orbis cometici, deque admirandis coeli characteribus

The first part of his work () followed Galileo's ideas on comets. The second part () consisted of four main sections. The first concerns the classification of nebulas. Hodierna classified the objects into three types according to their resolvability. Luminosae, or star clusters to the naked eye, Nebulae, or clusters that appeared nebulous to the naked eye, but which were resolvable in his telescope, and Occultae, which did not resolve even with the aid of his telescope. The second part is a list of 40 nebulae, of which roughly 25 have been identified as known objects, the others having too unclear a description for a modern identification. The third section is an attempt at a unifying theory of celestial objects, and the fourth concerns Copernican heliocentrism. ==Discoveries==

Hodernia is credited with several first descriptions, discoveries and rediscoveries: These discoveries were part of an attempt at compiling a sky atlas, Il Cielo Stellato Diviso in 100 Mappe, but the work was never completed. ==References==