The newest known example of a rare type of object in the Solar System – a comet hidden among the main-belt asteroids – has been found and studied by Planetary Science Institute (PSI) Senior Scientist Henry Hsieh. Discovered to be active on July 7, 2021, this asteroid (248370) 2005 QN137 is just the eighth main-belt asteroid, out of more than half a million known main-belt asteroids, confirmed to not only be active, but to have been active on more than one occasion. This behavior strongly indicates that its activity is due to the sublimation of icy material. As such, it is considered a so-called main-belt comet, and is one of just about 20 objects that have currently been confirmed or are suspected to be main-belt comets.