The number of unexplained flying objects that many eyewitnesses believe are ships of aliens traveling to Earth seems to be on the rise. The last UFO sighting took the form of a strange black ring in the sky over Denver (USA), writes express.co.uk.
It seemed that the whole city was observing an unusual object, but the exact explanation of what it is is still a mystery.
From the trail of fireworks to the activity of volcanoes, many explanations have been given on the Web.
The famous Taiwanese ufologist Scott Waring gave his explanation for the bizarre ring phenomenon. He suggested that the black ring is the outline of an alien ship.
According to the ufologist, the UFO moved so quickly in the air that it left a black ring of smoke around it.
However, the description under this YouTube video contains a much more reasonable explanation for this phenomenon. The author believes that the strange "ring" is a byproduct of the pyrotechnics used during the supercross competition at Mile High Stadium (Denver, USA).