ROCKS SMACKING EARTH
More frequent than before
WASHINGTON — Giant rocks from space are falling from the sky more than they used to, but don’t worry.
For the past 290 million years, large asteroids have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study in Thursday’s journal Science.
But no need to cast a wary glance up. Asteroids still only smack Earth on average every million or few million years, even with the increased crash rate.
NASA’s list of potential big space rock crashes shows no pending major threats.
The biggest known risk is a 1.3-km-wide asteroid with a 99.988% chance it will miss Earth when it passes in 861 years.
“These events are still rare and far between that I’m not too worried about it,” said study lead author Sara Mazrouei, a University of Toronto planetary scientist.
Mazrouei and colleagues in the United Kingdom and United States compiled a list of impact craters on Earth and the moon that were larger than 20 km wide and came up with the dates of them.
Outside scientists are split about the research, but Harvard’s Avi Loeb said the case was convincing.
Humans might not have emerged without mass extinctions millions of years ago, Loeb said in an email, adding, “but this enhanced impact rate poses a threat for the next mass extinction event, which we should watch for and attempt to avoid with the aid of technology.”