A strange half-moon or boomerang-shaped UFO was captured on video as it flew out of one of Mexico’s most active volcanos. According to a UFO expert, the footage is definitive proof that the volcano is being used as an alien base.

The video of the incident was captured by YouTube user ColourUFO through the live camera networks monitoring the Popocatépetl volcano located in central Mexico.

In the video, which is over 45 minutes long, the volcano can be seen spewing clouds from its crater. During its display of volcanic activity, a glowing object appeared near its base and began to slowly move upwards toward the sky.

The object, which had a distinct crescent shape, maintained slow speeds as it cruised across the side of the volcano. It continued moving upwards until it completely disappeared in the sky.

Scott Waring of ET Data Base noted that the UFO was almost half as big as the crater of Popocatépetl. Since the crater has a diameter of 1,970 feet, he estimated that the UFO could be about 787 feet-long.

For Waring, the footage can be regarded as clear evidence of the alien activity within the volcano. Like other UFO enthusiasts, he believes that a UFO base is situated about 3 miles below the active volcano.

The claims regarding the existence of the volcano’s alien base may have stemmed from similar sightings in the past.

In 2013, the Mexican media company Televisa, which at that time monitored the activities of Popocatépetl, filmed a UFO as it flew toward the volcano and entered its crater.

Marc Dantonio, the chief photo and video analyst for the Mutual UFO Network said that the video was authentic after analyzing it.

“What I think is that this is not likely a fake,” he told Huffpost. “I think, for the moment, this is a genuine image capture.”

“This is a low light camera which allows volcanologists studying the footage to see any incandescence on the flank of the volcano in night shots,” he added. “As such, any brighter lights that are captured will appear very bright, as the one planet/star indicates.”