The blue fireball made the Spanish sky as bright as day

The fireball from the comet debris moving at 160,934km/h emitted blinding white, green and blue light near midnight.

Fireballs lit up the Spanish sky last weekend. (Video: ABC News)

On May 18, people across Spain and Portugal had the opportunity to witness a fireball explode right above their heads, according to Space . Near midnight, the fireball streaked across the sky , leaving behind a brilliant trail. Footage widely shared on social networks captures the scene of white, green and blue light from the fireball making the night sky as bright as day.

Stony meteorites frequently pass through Earth's atmosphere at high altitudes. But last weekend, the object appeared in the sky of the two countries moving at breakneck speed, about 160,934 km/h, more than twice as fast as a normal asteroid. Experts believe that its flight path is quite strange because it is a fragment of a comet, an icy body formed in the early days of the Solar System. It broke up 60km above the Atlantic Ocean and no debris reached the ground, according to the European Space Agency.

According to Meg Schwamb, a planetary astronomer at Queen's University Belfast, it is not uncommon for comets to create meteor showers . "We have many large meteor showers throughout the year, which result when the Earth passes through a cloud of comet debris ," Schwamb said. For example, the Perseid meteor shower that occurs every August results when Earth passes through the remnants of comet Swift-Tuttle. Those meteor showers light up the sky in a similar way to the object that caught fire last weekend.

The blue fireball fell on Spain.

The air in front of the object compresses and heats up, causing it to erode, crack and break up. The destruction process releases light and shock waves if the object is large enough. Schwamb speculates that the object that created the fireball in Spain and Portugal was slightly larger than the meteorite often seen in meteor showers, so it was brighter.

In addition to the blinding light, the breakup of the comet fragment could help experts develop ways to protect Earth from large asteroids. Researchers fear that some missed celestial bodies that are not detected in time will explode with dangerous impact above the city. For example, the 16.8 m meteorite that exploded above the Russian city of Chelyabinsk in 2013, was not detected in advance. Its mid-air explosion was equivalent to nearly 500,000 tons of TNT, causing widespread damage and injuring at least 1,200 people.

However, a new generation of observatories coming online in the next few years, including the Vera C. Rubin observatory in Chile, could detect millions of previously unknown faint asteroids.