Social media users were perplexed by unusual sighting in the viral video, with one saying "genuinely what is this." ...

Have you got a sharp eye? Put your vision to the test by trying this puzzle, which asks you to spot the plane in the sky. As aircraft tend to be huge, you shouldn't think it would be that difficult.

Legends of the Sky: The Liberty Plane is available to stream on pbs.org and the free PBS App, available on iPhone, Apple TV, Android TV, Android smartphones, Amazon Fire TV, Amazon Fire Tablet ...