"A possible explanation" When low on the horizon, the spectrum of color contained in starlight could be refracted by the air and dispersed by turbulence. In simpler terms, the colors contained in starlight don't all reach the human eye at the same time. The phenomenon creates the illusion of a flashing light changing colors. Sine added that a star seen at tree level could easily "disappear" or move below the tree tops. As for the lights movement, it could simply be an optical illusion which occurs when the human eye has no reference point to help frame an object. The object may, therefore, appear to bob and weave in the sky. "I'm not saying that's the case, but it is one possibility," Sine said. He also said similar sightings come from Alberta when the planet Venus appears in the sky. It sometimes appears to emit colored lights and move around. Sine's organization, which has been investigating UFO sightings since 1994, keeps records of all the reports it receives. He said the other NWT sighting the group received was from Yellowknife last summer. Originally, the Calgary-based organization only looked into Alberta UFO sightings. WIth the rise of the Internet, Sine said his group has been looking into sightings all over the world.