The asteroid that wiped out the dinosaurs set off an intense heat wave that briefly boiled the Earth’s atmosphere – but it didn’t burn off all the plants.
Humanity has not been unlucky enough to observe at first hand the effects of a large impact, so to investigate whether a massive asteroid would spark off a global wildfire we had to turn to the laboratory. We have modelled, for the first time, the heat generated by the impact and what it meant for the planet’s plants. Our research is published in the Journal of the Geological Society.
This all happened 65m years ago at the end of the Cretaceous period, when dinosaurs still roamed the earth. Suddenly, between 60 and 80% of all living species became extinct. Until the 1980s, this catastrophic loss of life was a mystery, but then scientists found a clue – traces of the element iridium in rocks of this age. Iridium generally falls to Earth with extraterrestrial objects. This suggested a massive asteroid collided with the planet and that this could be responsible for the mass extinction.
Ten years later, scientists found the 65m year-old, 180km wide, Chicxulub crater on the Yucatan Peninsula in Mexico, which finally provided the smoking gun that could explain the apparent chaos at the end of the Cretaceous era. A crater that wide suggests that an asteroid or comet approximately 10km wide hit the Earth.
The impact would have released a huge amount of energy – equivalent to more than a billion Hiroshima bombs. The asteroid itself was vaporised as it smashed into the Earth and in doing so vaporised and blasted out particles of the rock that it hit.
A huge glowing ball of hot rock and vapour rushed up from the impact site at huge speeds, ejecting it way above the atmosphere up into space. As it hit the cold of space it decelerated, cooled and rained back through the atmosphere, re-solidifying and forming tiny droplets of rock known as “spherules”.
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