On Jan. 14 of last year, an Air Canada pilot flying from Toronto to Zurich, Switzerland, woke up from a nap to see an alarming sight out the cockpit window: what appeared to be a flying object (presumably another plane) flying directly at him. He immediately took evasive action, sending the jet into a steep, sudden dive that injured 16 people and almost resulted in a midair collision with another aircraft flying 1,000 feet lower.

It was a terrifying, bizarre event over the Atlantic Ocean, but what makes it even stranger is that, according to a new report from the Transportation Safety Board of Canada, the pilot was reacting to an optical illusion. The pilot thought it was a UFO -- quite literally, an unidentified object flying at the plane. Yet there was no aircraft, identified or otherwise: The pilot had instead seen reflected sunlight from the planet Venus.

Depending on when you measure it (since everything in the universe is in constant motion), Venus is between about 25 million and 162 million miles away. Yet the pilot thought that it was close enough to pose an imminent threat of collision. How could the pilot's estimate of the light's distance to the plane be off by at least 25 million miles? How could an experienced airline pilot mistake a planet for a plane?

It's actually not that difficult to understand and has implications for other UFO sightings.

Not ALL other UFO sightings, though. To read more, click here.