What would it take for the K-T event to happen again as well as the possibility?
The K-T extinction event is thought to be caused by the impact of an asteroid around 10 km in diameter.1 However, mass destruction of life on Earth does not require an asteroid that large. It has been theorized that for an asteroid to cause the extinction of humans on Earth, it would need to be at least 1 km in diameter. Asteroids of this size are estimated to impact the Earth around every 500,000 years.2
Asteroid impacts are an ever-present threat to life on Earth. An asteroid impact of significant size is just as likely to happen tomorrow as it is to happen 300,000 years from now.3 In fact, there have been several “near misses” in the past several years, such as 2004 FH passing within 40,000 km of Earth in 2004 and 2004 FU162 passing within 6500 km of Earth, also in 2004.
There are even asteroids which we have detected to have a chance of impacting the Earth in the future. These asteroids include 2007 VK184, which has a 1 in 2940 (.034%) chance of impacting the Earth in 20484, as well as (29075) 1950 DA, which, depending on the direction of its polar rotation, has either a 1 in 300 chance of impacting Earth in 2880.5 It should be noted that 2007 VK184 is around 130 m in diameter and so would probably not have the capability of eliminating human life on Earth. However, (29075) 1950 DA has a diameter around 1.1 km to 1.4 km, and so would probably cause the extinction of the human race upon impact.
