September 03, 2015: Onlookers were confounded by a strange whisp of cloud in the early morning sky of Florida, left by the launch of an Atlas V rocket carrying a US Navy satellite.

For astonished onlookers it seemed like a UFO, an alien phenomenon lighting up the skies in Florida.

But though a massive teardrop-shaped light did come from a spacecraft, the explanation is far less exciting than the spectacle.

The stunning bubble was actually the trail of an Atlas V rocket being launched from Cape Canaveral about 6am yesterday local time.

If you look closely, you can see the rocket itself as a tiny speck at the front of the spectacle.

The smoke trail was illuminated by the rising sun, creating a brilliant sight above a nearby airport, where it was filmed by traveller David Lopez.

"What the f--- is that?" Lopez can be heard saying.

"That's crazy, bro."

The United Launch Alliance rocket was taking a Navy military satellite into space.

© ninemsn 2015