A meteor shower detected in February was likely caused by an undiscovered comet that could pose a threat to the Earth, a U.S. astronomer said on Monday. The debris may have been shed by a long-period comet, said Peter Jenniskens, of the Search for Extraterrestrial Intelligence (SETI) Institute. He added however that astronomers did not know whether the comet "has already passed us by or is still on approach." "The meteors are in a very compact cluster, not wider than our measurement uncertainty. They move in essentially the same orbit," he wrote in reply to questions sent by RIA Novosti. He confirmed his earlier prediction of their possible return in 2016 or 2023, and after that not again until 2076. Jenniskens heads the Cameras for Allsky Meteor Surveillance (CAMS) project, which has been monitoring the San Francisco Bay Area's night skies with low-light video cameras in an effort to map meteor showers. The comet that produced the meteor shower is unknown. "This comet survived some prior passages through the inner solar system to get in the orbit where it is now, so the comet is likely still there," Jenniskens said. The video techniques used in the research make it possible to detect much more diluted trails from comets that have somewhat longer orbital periods, he said.