The Guardian - It is a scenario beloved of Hollywood: a huge asteroid, several miles wide, is on a collision course with Earth. Scientists check and recheck their calculations but there is no mistake – civilisation is facing a cataclysmic end unless the space rock can be deflected.
It may sound like science fiction, but it is a threat that is being taken seriously by scientists.
Earlier this year, researchers estimated that asteroid YR4 2024 had a 3.1% chance of hitting Earth in 2032, before revising that likelihood down to 0.0017%. This week, new data suggested it was more likely to hit the moon, with a probability of 4.3%.
If that happens, the 53- to 67-metre (174ft-220ft) asteroid previously called a “city killer” will launch hundreds of tonnes of debris towards our planet, posing a risk to satellites, spacecraft and astronauts.
Before that, in April 2029, 99942 Apophis – an asteroid larger than the Eiffel Tower – will be visible to the naked eye when it passes within 32,000km of Earth. This attention-grabbing close encounter has prompted the UN to designate 2029 as the international year of planetary defence.
When it comes to apocalyptic asteroid strikes, there is precedent, of course. Most scientists believe such an event hastened the demise of non-avian dinosaurs 66m years ago.
“This is something that happens,” said Colin Snodgrass, a professor of planetary astronomy at the University of Edinburgh. “Not very often, but it is something that happens. And it’s something that we could potentially do something about.
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