Holes in the Earth: 170 and Counting

At last count, there were more than 170 known impact craters on our planet, according to the Earth Impact Database maintained by the University of New Brunswick in Canada. These puncture wounds are littered over every continent, as well as the seafloor.

There would be countless more if it weren't for Earth's constant remodeling. Plates shift, mountains form, volcanoes erupt and erosion washes over the planet's surface, continually hiding the evidence of most craters.

"If there was no erosion or tectonic activity, we would look like the moon," said Lucy Thompson, a geologist at the University of New Brunswick. "The moon is just pockmarked with impact craters." - space