5+ Times the Earth Was Devastated by Meteorites
Meteorite impacts are actually more common than you might first think. While most do not lead to mass extinction events like the one that might have ended the dinosaurs, they are far from a rare event.
Here we investigate some of the biggest ones in history and find out just how regularly Earth is peppered by them.
What was the biggest meteor to hit Earth?
According to various sources, the largest yet discovered meteorite impact crater is the Vredefort crater in South Africa. This monster has a diameter of around 300 km and the impact occurred sometime in the Palaeoproterozoic era (around 2 billion years ago).
This geological era is one of the longest in Earth's history and is thought to have been the time that the Earth's continents first stabilized. But that is about as recognizable as the planet would be to us today.
The Earth's rotational rate was much faster than today and a day lasted around 20 hours. A year, at this rate, would last around 438 days.
Life on Earth was mainly microbial and the atmosphere would not have been pleasant at all. At some point, during this period the largest verified meteorite impact on Earth occurred.
Little evidence remains today as most of the impact crater has since been eroded away. But there is very striking evidence remaining of the event in the central dome of the impact site.
In 2005, the Vredefort Dome was added to the UNESCO World Heritage Site list because of its fascinating geological importance.
When was the last time a meteor hit Earth?
This is a more interesting question than it may at first seem. Our planet is actually regularly subject to meteorite impacts.
Most experts estimate that, on average, the Earth is struck between 5 and 10 times a year. Of course, most of these are very small and usually go completely unnoticed.
One of these hit Earth in December 2018. According to Popular Mechanics, this meteorite had the force of a nuclear bomb and nobody even noticed.
"Last December, the Earth had a very special visitor. According to NASA, a tremendous fireball exploded in the atmosphere, the second-largest in 30 years and the largest since the Chelyabinsk incident of 2013." - Popular Mechanics.
This meteorite exploded about 26 km above Earth's surface with the same force of about 10 Hiroshima atom bombs.
How often do meteorites hit Earth?
As we have already highlighted, meteorite impacts on Earth are actually something of an occupational hazard for our planet. To reiterate, it is estimated that between 5 and 10 meteorites a year end their days hitting our home planet.
Of course, many more actually miss us completely.
As scary as this sounds, most meteorites burn up in Earth's atmosphere during entry but those that do make it through tend to hit unpopulated areas or the Earth's extensive oceans.
But, as we know, Earth's history is littered with evidence of much larger and more deadly impacts. Most of these would have been devastating events for Earth's biosphere with some notable ones causing or contributing, to mass extinction events.
Thankfully, these monster meteorite impacts are very rare events. On average, asteroids with 1 km diameters strike Earth every 500,000 years or so.
True monsters of around 5km + diameter strike Earth approximately every 20 million years.
What happens when a meteorite hits Earth?
This completely depends on the size of the meteor in question. For smaller ones (less than 1 km in diameter), they tend to either burn up in the atmosphere or explode at high altitude (bolides).
But for larger ones, the event can be pretty serious for the planet. For example, if a 10 km-sized meteor were to hit Earth the result can be devastating.
According to Cornell University, it doesn't actually matter where it hits (land or sea) would not be slowed down to a significant degree. When it makes an impact with the Earth's surface it would release pretty much all of its energy in one go.
This would vaporize the meteorite and a large part of the Earth's crust at the impact site. Rock, dust and molten material would be thrown high into the air.
Pressure waves and seismic activity would flatten trees and other structures close to the impact site.
A crater would form within moments of around 10 km in diameter. Some ejecta would be released back into space, but the rest would rain down over a large radius around the impact site.
This material is intensely hot and would create wildfires for miles around. But that is just the start.
Over the following months and years, a combination of dust from the impact, and fires would choke the Earth's atmosphere. This would block the amount of sunlight that could reach Earth's surface putting any surviving plants and trees under intense stress killing most plant life on Earth.
With little or no plant life to consume the food chain would soon completely collapse. Many animals would quickly perish.
It would lead to mass extinction on Earth akin to the Late Cretaceous mass extinction that killed the dinosaurs.
What are the largest meteorite impacts in Earth's history?
With all that in mind, you might be wondering what the largest meteorite impacts ever in Earth's history are? The following list is far from exhaustive.
1. Vredefort, South Africa
As previously mentioned, Vredefort crater in South Africa is the largest confirmed meteorite impact event in Earth's history. It occurred around 2 billion years ago and left a crater about 160 kilometers wide.
This would have been a truly devastating event.
2. Sudbury Basin, Ontario, Canada
Hitting Earth about 1.8 billion years ago, this is one of the world's largest meteorite impact sites ever discovered. It is also one of the world's oldest impact structures.
The Sudbury Basin crater has an estimated diameter of 130 kilometers. Geological surveys have found debris from the crater over an area of about 1,600,000 km2 most of which have been thrown about 800 km from the impact site.
3. Chicxulub, Yucatan Peninsula, Mexico
Probably the most famous meteorite impact in Earth's history, Chicxulub is another of our planet's largest meteorite impacts. It has entered the public eye as the main culprit for ending the dinosaurs.
The crater has an estimated diameter of between 150 and 300 km. If larger estimates are correct, this could have been larger than Vredefort.
Most estimates of the meteorite's size range from between 11 to 81 km.
4. Popigai, Siberia, Russia
Popigai in Siberia, Russia is another of Earth's largest meteorite impact events. Estimated to have hit Earth about 36 million years ago, the site is littered with impact diamonds.
The crater has an estimated diameter of 90 km and is thought to have contributed to the Eocene-Oligocene extinction event.
5. Manicouagan, Quebec, Canada
Smacking into Earth about 215 million years ago, Manicouagan Crater's meteorite is another of Earth's most deadly impact events. The resulting crater that formed has an estimated diameter of 100 km.
The present-day Lake Manicouagan now sits in what is left of the impact site. It is estimated the meteorite was about 5 km in diameter.
The impact crater is so large it can actually be seen from space and is colloquially called the "Eye of Quebec".