In 2006 Hsieh & Jewitt published the discovery of several main belt asteroids observed to have tails (just like comets do), which activate when nearest the Sun (just like comets do). In this paper, Licandro et al. test the origins of two so-called “main belt comets” by looking at spectra.
Observational astronomers often need data from sophisticated, expensive, and rare telescopes perched on top of mountains or the edge of space. The authors of this paper showcase a totally different technique that harnesses a Yahoo! image search to figure out the orbit of a comet.
Compositional investigations of comets have suggested that they are “icy dirtballs,” so would it be possible to detect traces of hydrogen and oxygen if they were flung from one stellar system into the atmosphere of another star?