Comet hits Earth's atmosphere, flies over Spain, Portugal before burning up - ESA

A comet streaked across the sky above Spain and Portugal over the weekend as it impacted Earth's atmosphere, eventually burning up over the Atlantic Ocean, the European Space Agency (ESA) confirmed. 

Footage of the comet in Spain and Portugal on Saturday were spread over social media, where it can be seen in the form of a blueish-green ball of fire flashing through the night sky. This includes one shared by the ESA, which it originally described as a meteor flying over the city of Caceres in Spain. 

White at first appearing to be a meteorite, the ESA later confirmed that it was a small piece of a comet, something backed up by a preliminary analysis by Andalusia's Institute of Astrophysics. The comet fragment flew through the air at 45 kilometers per second, which is over 131 times the speed of sound.

Fireball update!It appears that this object was a small piece of a comet.We estimate that it flew over Spain and Portugal travelling at ~45 km/s before burning up over the Atlantic Ocean at an altitude of ~60 km.The likelihood of any meteorites being found is very low. https://t.co/OZdo37QsFX

— ESA Operations (@esaoperations) May 19, 2024

To put that speed into a more relatable comparison, it would take less than a second for this comet to have traveled the entire distance of a marathon.

Are comets dangerous? 

The ESA said that the comet burned up in the atmosphere as it entered, likely burning up 60 kilometers up in the air. As such, it is very unlikely that any fragments - meaning meteorites - would be found, even if it had landed on the ground and not in the ocean. 

This is the ultimate fate of most asteroids and comets that enter the atmosphere, harmlessly burning up in the sky. 

However, what is also notable is that no one had seen this comet coming. 

In response to a query by science journalist Dr. Robin George Andrews, the ESA confirmed that the comet had not been tracked or reported prior to impact. 

Hello! It was definitely not tracked or reported prior to impact. We are currently checking whether there is any 'precovery' information (i.e. if we can find it in any existing data retrospectively).

— ESA Operations (@esaoperations) May 19, 2024

While the field of planetary defense has advanced enough that we can see most asteroids and comets heading toward Earth, there are many that go unnoticed, sometimes due to flying through a blind spot. 

Comets themselves are, like asteroids, massive objects in space. But while asteroids are huge bodies of rocks and minerals, comets are formed of mostly dust, gas, and ice. They are also surrounded by a cloud of gas called a coma, which is what forms its tail. 

They can, in theory, be dangerous, should a large enough comet come barreling towards Earth - just as an asteroid can be dangerous. However, the field of planetary defense has seen scientists make strides towards protecting the Earth from these scenarios, should one ever happen in the future. NASA's Double Asteroid Redirection Test (DART) mission, which successfully altered an asteroid's orbit, is currently the most promising method of keeping the Earth safe from dangerous space hazards.

Reuters contributed to this report.