In case you weren’t convinced that humanity was doing enough to destroy Earth you were always safe in the knowledge that an asteroid apocalypse would probably finish the job.
Unfortunately, a new study has found that the likelihood of a fiery ball from space wiping us off the face of the planet is actually far less than we thought, as our atmosphere is protected by an invisible shield.
Researchers had long known that meteors often blow up as they reach the surface of the Earth, but had never been able to pin down why this was the case.
Now NASA’s Planetary Defense office (coolest job ever) have been looking at the Chelyabinsk explosion - that happened over a remote area in Siberia in 2013 - and injured hundreds of people.
The meteorite brought with it the same force as a small nuclear weapon, so when it entered Earth’s atmosphere it created an understandably huge shock blast.
When researchers later recovered the debris from the blast, they found only 2,000 tons of material - when the meteor itself was estimated to be as large as 10,000 tons.
This means that something must have happened in the upper atmosphere that allowed it to disintegrate in this way.
They found that when a huge ball of rock comes hurtling towards Earth, the high-pressure air in front of it seeps into pores and cracks, pushing the body apart and causing it to explode.
Professor Jay Melosh, said: “There’s a big gradient between high-pressure air in front of the meteor and the vacuum of air behind it. If the air can move through the passages in the meteorite, it can easily get inside and blow off pieces.”
In order to reach these findings, the team used a unique computer code that allows both solid material from the meteor body and air to exist in any part of the calculation.
“Most of the computer codes we use for simulating impacts can tolerate multiple materials in a cell, but they average everything together.”
“Different materials in the cell use their individual identity, which is not appropriate for this kind of calculation,” said Melosh.
While we can breathe a sigh of relief that this mechanism may protect Earth’s inhabitants from small meteoroids, as the dinosaurs know only too well, large ones likely won’t be bothered by it and will fly straight through.
For those city-sized objects humanity will need to come up with its own plan, something that NASA’s Planetary Defense office is already working on.