Are there aliens on the moon? Alien hunters has spotted a mysterious disc flying past the surface of the moon. The alleged UFO was captured during a live stream video of the lunar surface on Dec. 3 of the Miami Observatory in Florida.

During the video, a dark disc-shaped object appeared on the moon's surface. The video was posted by YouTube user UFOVNI UFO Sightings with the title "UFO crossing the moon."

The alleged UFO sighting has prompted many UFO experts to speculate that the mysterious disc-shaped object is not just a trick of the eye, because it has appeared in different photos which refutes the assumption that it's just a coincidence.

'It's not a man-made object, because there are not solar panel wings on it to gather energy," speculates Scott C. Waring on his website, via Daily Mail. "There are no antennas on it for transmitting, also the surface is not completely round, but has a rough edge to it. Looks like a bio-mechanically grown UFO."

Meawhile, in other alien sightings, some alien enthusiasts believe that they have finally found an evidence of architecture on Mars. The theorists claim that they have, in fact, spotted towers on the red planet that are as high as three miles.

The alleged sighting was noted by the YouTube channel Mundodesconocido, saying: "Investigating on some Mars images, we have recently found a row of huge towers located in the Martian area of Terra Meridiani. Due to their peculiar features, we believe that they have an artificial origin. In the following video, we will show you all the amazing information, evidences as well as animated 3D models that will allow you to evaluate correctly the information we propose."

Excited as the idea of alien life existing outside Earth might be, these news should be taken with a grain of salt until humanity and science has reached a point to prove that they do exist.