A mysterious 'UFO' seen in the sky over Moscow has sparked speculation that the city has been visited by an alien spacecraft.The pyramid-shaped object was said to have remained for hours over the Red Square in the Russian capital.The fuzzy grey shape was apparently captured on film in at least two separate videos – one filmed during the daytime and another at night – which became an online sensation.But sceptics suggested there would be thousands of videos, rather than just two, if the object really had remained in the skies for hours.Full story: SkyNews