An asteroid discovered more than 100 years ago may not be an asteroid at all, but an extinct comet that is coming back to life, according to new observations.

The night of December 11, Steve Larson with the Catalina Sky Survey (CSS) at the University of Arizona was searching for potentially hazardous asteroids when he came across what looked like a comet — a faint, wispy tail surrounding a bright, starlike core. Four images taken over the course of 30 minutes revealed the object was moving relative to the background stars.

"Its brightness of a total magnitude of 13.4 visual, which is about 900 times fainter than the faintest star you can see in a clear, dark sky, led me to suspect that it was a known comet, but I checked the comet database and got nothing," Larson said.

According to Larson, comets are thought to be a major source of Earth's water, and "extinct" comets may be useful resources for space exploration.

Further investigation revealed that the object was a known asteroid called (596) Scheila, discovered in 1906. The extraterrestrial rock is tumbling through space alongside thousands of similar objects in our solar system's main asteroid belt, roughly between the orbits of Mars and Jupiter, out of the ecliptic plane in which most planets and asteroids travel.