Watch: Strange blue light an 'invasion from space'

Airport workers were left scratching their heads after spotting what looked like a giant UFO in the sky.

The incredible footage, believed to have been filmed at Miami Airport, led to those on the tarmac whipping out their camera phones to snap the strange phenomenon.

"Check that out, woah, it's going to hit the plane," shouts one man, as the strange blue shape moves through the sky.

The person recording then moves position to show that the object is quite clearly moving through the night sky.

After being shared on LiveLeak, it led to people discussing just what the strange blue light was in the sky.

User RamJ described how it was "the invasion from space", while another unnamed user says it is 'possible comet fragment with a high content of water and frozen gasses'.

Many of those commenting on the clip believe it is something entirely normal.

One user says it is a "Florida rocket launch", and another agrees, saying the "plume is from a hydrogen powered rocket engine, water vapor condenses in the high altitude forming a cloud of ice crystals reflecting light from the sun which, from this viewpoint, is below the horizon."

Although it is not known when this footage was shot, on June 24 the Atlas V rocket was fired off from Cape Canaveral Air Force Station.

The rocket was fired into orbit loaded with a Navy satellite.