A bright comet fragment lit up the skies over parts of Spain and Portugal over the weekend, treating stargazers to a rare spectacle.

The European Space Agency (ESA) shared a video captured by its "fireball camera" on X (formerly Twitter) on Sunday of what it described as a "stunning meteor".

The agency said the blue light streaking across the sky over the western Spanish city of Caceres — near the Portuguese border — was travelling at roughly 45 kilometres per second.

But two hours later, the ESA took to X once again to inform the public the meteor was in fact a "small piece of comet".

"The likelihood of any meteorites being found is very low," it added.

That means it is unlikely the comet hit the Earth's surface.

The ESA estimates the comet burned up over the Atlantic Ocean at an altitude of 60km.

The Spanish Calar Alto astronomical observatory also said a preliminary analysis by Andalusia's Institute of Astrophysics revealed the object had a "cometary origin".

Scientists at the CSIC (Spanish National Research Council) estimate the fireball streaked across the atmosphere for 500km "before going extinct".

Videos filmed from several cities and towns in both countries were circulating on social media.

During a concert in the Portuguese city of Barcelos, the object was filmed streaking across the sky as the singer performed.

One Lisbon resident, Bernardo Taborda, told Reuters he was walking around the city with friends when the sky suddenly turned bright green.

"It almost looked like daylight … we all looked back and saw it," Mr Taborda said.

"It felt like a movie, we all looked at each other and we were stunned."

Story By: ABC with wires

Original Story link: https://www.abc.net.au/news/2024-05-20/blue-green-comet-spain-portugal/103868608