WHAT KILLED THE DINOSAURS?

The object that caused Earth’s last mass extinction may not have been an asteroid

Researchers are fairly certain that the object known as the Chicxulub impactor ended the dinosaurs’ reign over Earth 66 million years ago when it crashed into the planet. The huge impact released energy equivalent to the detonation of 21 to 921 billion nuclear bombs, so it wasn’t just the dinosaurs that bore the brunt of the devastation. The impact sparked what geologists call the Cretaceous-Tertiary (K-T) extinction, an event that saw the elimination of around 80 per cent of the planet’s animal species.

Evidence of this violent impact is found in Earth’s geological record, most strikingly in the shape of a 150-kilometre (93-mile) wide and 19.3-kilometre (12-mile) deep crater carved into our planet at the Yucatán Peninsula in Mexico. Yet despite the wealth of information about this collision between Earth and the Chicxulub impactor, there are still mysteries surrounding the object itself and the processes that caused it.

One of the most pressing puzzles that surrounds the Chicxulub impactor is just where this 80-kilometre (50-mile) wide ‘planet killer’ came from, and the details of its journey to

Earth. The source of this mystery is the fact the impact rate for the main suspects – both main-belt asteroids and long-period comets – are just too low to account for the Chicxulub event.

Unlocking the mysteries of the Chicxulub impactor is the goal of Abraham ‘Avi’ Loeb of the Harvard-Smithsonian Center for Astrophysics and Amir Siraj, an astrophysicist at Harvard University. Their work implies that the solution to this puzzle may reveal that the asteroid that killed the dinosaurs wasn’t an asteroid at all – rather it could have been a piece of ‘shrapnel’ originating from a long-period comet that was dragged from its position at the edge of the Solar System and violently ripped apart. The research could also show that the threat to Earth from objects falling from space is more considerably significant than currently estimated.

“In the early 1980s, Luis Alvarez, a Nobel laureate in physics, and his son, geologist Walter Alvarez, made the breakthrough discovery that the Chicxulub impactor and the global extinction that occurred around the same time were connected,” Siraj tells All About Space. “This sparked intense scientific interest in understanding the origin of the impactor. But the more that theorists looked at the puzzle, the stranger it became.”

Loeb and Siraj are the authors of a paper published in the journal Scientific Reports documenting one possible origin for the Chicxulub impactor, its journey to our planet and how this was influenced by the Solar System’s other bodies. The duo’s model confirms that the object could

“long-period comets may also pose long-term hazards to humans and Earth’s biosphere”

Manasvi Lingam