Spectacle in the Night
A fireball streaked across the skies of Spain and Portugal late last week, creating a brilliant display of green, blue, and white light that lit up the night sky like daylight, according to Space. At around midnight, the fireball shot through the atmosphere, leaving a luminous trail in its wake. Videos shared widely on social media captured the spectacular sight, as the celestial object blazed through the night.
Origin and Speed
Meteors, or rocky debris from space, frequently enter Earth's atmosphere at high altitudes. But the object that streaked over the Iberian Peninsula last weekend was moving at an unusually fast speed—approximately 100,000 miles per hour (160,934 kilometers per hour)—about twice as fast as a typical meteor. Experts believe its peculiar trajectory suggests it was a fragment of a comet, an icy celestial body that formed during the early days of our solar system. It broke apart about 37 miles (60 kilometers) above the Atlantic Ocean, and no fragments reached the ground, according to the European Space Agency.
Cometary Connection
Comets are known to shed debris that creates meteor showers, said Meg Schwamb, a planetary scientist at Queen's University Belfast. "We have major meteor showers throughout the year as the Earth passes through clouds of debris from comets," Schwamb said. For example, the Perseid meteor shower visible each August is the result of Earth passing through debris from the comet Swift-Tuttle. These meteor showers illuminate the night sky in a similar manner to the fireball seen last weekend.
Atmospheric Interaction
As the fireball hurtled through the atmosphere, the air in front of it was compressed and heated, causing it to ablate, break apart, and disintegrate. This process releases light and shock waves, if the object is large enough. Schwamb speculates that the object that created the fireball over Spain and Portugal was somewhat larger than the meteors typically seen in meteor showers, which is why it was so bright.
Significance for Planetary Defense
In addition to its dazzling display, the breakup of the cometary fragment could help experts develop ways to protect Earth from larger asteroids. Scientists are concerned that undetected, potentially hazardous objects could detonate high above cities. For example, a 55-foot (16.8-meter) meteor exploded over the Russian city of Chelyabinsk in 2013, undetected beforehand. Its airburst was equivalent to nearly 500,000 tons of TNT, resulting in widespread damage and injuring around 1,200 people.
Early Warning Systems
However, a new generation of observatories set to come online in the next few years, including the Vera C. Rubin Observatory in Chile, could detect millions of previously unknown, faint asteroids. These observatories will significantly enhance scientists' ability to track potential threats and provide valuable warnings.
Summary
A bright green fireball illuminated the skies of Spain and Portugal last weekend, leaving a vivid trail of light that lit up the night like daylight. The object, believed to be a fragment of a comet, traveled at an unusually high speed and disintegrated about 37 miles above the Atlantic Ocean. This spectacular event highlights the potential hazards posed by undetected asteroids and the need for improved early warning systems to protect Earth.