Greg Leonard, a professor at the University of Otago’s School of Surveying (New Zealand) and senior research specialist at the NASA-funded Catalina Sky Survey project, has said there is 100-percent possibility of an asteroid hitting Earth.
Speaking to science writer Bryan Walsh for his new book on the history of extinction, called ‘End Times: A Brief Guide to the End of the World’, Leonard conceded that the chances of being killed by an asteroid are less than dying from a lightning strike.
“But I also know that if we do nothing, sooner or later, there’s a one hundred percent chance that one will get us,” he added. “So I feel privileged to be doing something.”
Leonard said that when a large near-Earth object ends up on a collision course with the planet, humanity will need a little more than intelligence-gathering to avoid a disaster.
Earth is constantly bombarded by cosmic dust and high-energy particles, but asteroid impacts are observed rarely and always become quite an event.
About once a year, according to NASA’s Jet Propulsion Laboratory, a car-sized asteroid enters Earth's atmosphere and burns up before reaching the surface, causing no damage.
A space rock measuring between 25 meters and one kilometre in size is likely to cause local damage to the impact area, while an asteroid larger than one kilometre would be likely to cause serious damage to the world's climate – but such catastrophes are estimated to occur just a few times in every million years.
A collision with an object larger than five kilometres is thought to be damaging enough to cause mass extinctions – as was the case with the Chicxulub impactor, which hit the Earth just off what is now the Yukatan Peninsula 66 million years ago, wiping out some three-quarters of the planet’s plants and animals, including all non-avian dinosaurs.