As seen in impact craters all over our planet, there have been many Earth-shattering hits made by meteorites and comets over the eons — including two remarkable lakes in Greece which many researchers believe are the result of two meteorites hitting the surface there 10,000 years ago.
Still filled with water, they look almost like artificial ponds. But, like many other impact craters around the world, at least 190 of which are still visible today, they appear to be the result of enormous hits our Earth has sustained as it catapults through space.
The Greek lakes, known as the lakes of Zerelia, in the region of Magnesia, are still filled with water today. That isn’t always the case with impact craters, however, and some craters are completely visible in their entirety, showing clear impact marks that demonstrate the unfathomable velocity of celestial objects that sometimes come all the way through our atmosphere and strike the Earth.
Known as “the twin space lakes,” the Greek craters may not be among the largest such formations on our planet, but they are striking in their nearly perfectly round shapes, which appear like eyes when viewed from the sky.
Located just a few kilometers outside the city of Volos and four kilometers (2.5 miles) from the town of Almyros, the two lakes are only 250 meters from each other, but were likely created by the tremendous impact of the space rock that catapulted through the Earth’s atmosphere.
According to scientists, approximately 10 thousand years ago, a meteorite hit the Earth, split into two and created the two twin craters, which then filled with water — and the lakes are still there today. Further research is needed to place them onto on to the world list of verified meteorite-made craters, but they are on a list of probable such sites.
Most meteors break up as they plunge through atmosphere
Contrary to what many might believe, the space rocks that blast through Earth’s atmosphere aren’t imposing in size at all, typically. They’re actually fairly small, with most measuring around 3 feet (1 meter) across, according to NASA.
Thanks to our dense atmosphere, most space rocks that are smaller than 82 feet (25 meters) in diameter won’t make it down to Earth, NASA says. The incredibly high speeds at which these objects are hurtling through space heat up the gases in the atmosphere, which actually burn them up.
Asteroids, meteors and meteorites have some important differences. Asteroids are small, rocky objects that orbit the sun. Although asteroids orbit the sun like planets, they are much smaller than planets.
Most of them live in the main asteroid belt — a region between the orbits of Mars and Jupiter, according to NASA. For example, some asteroids are found in the orbital path of planets. This means that the asteroid and the planet follow the same path around the sun. Earth and a few other planets have asteroids like this.
When asteroids, sometimes more prosaically called space rocks, encounter the atmosphere, they are then called meteors; when they make it to the ground, they are called meteorites. The pieces that do make it through usually cause little or no actual damage on the ground.
“The atmosphere protects us from impacts,” at least usually, says Paul Chodas, the director of NASA’s Center for Near Earth Object Studies at the Jet Propulsion Laboratory (JPL) in Pasadena, California, in an interview with Live Science.
Let’s take a look at some of the spectacular impact craters on Earth where meteors have made an indelible mark on our planet in the past 4.5 billion years of its existence.
The Chelyabinsk meteor
For most of us today, the recent meteorite impact that took place in Chelyabinsk, Russia, in 2013, was a wake-up call in that it could have landed anywhere on Earth and killed a great number of people if it had not hit exactly where it did — in a lake outside the city.
The shock wave alone after it hurtled through the skies and smacked into the frozen lake shattered windows and caused a good many injuries in Chelyabinsk, although thankfully no fatalities.
The meteor, which was originally 56 feet (17 meters) wide, measured a mere 1.5 meters (five feet) at the moment of impact, because so many parts of it burned up on entry. It landed in a lake, so it didn’t create a crater in the earth but rather in the lake bed.
Chelyabinsk meteor hurtled through atmosphere at 50 times the speed of sound
Most of the mass of the original meteor, which scientists now believe weighed between 12,000 — 13,000 metric tons, broke up on its journey through the atmosphere, as can be seen in the spectacular contrails it left in the sky as it did so, according to Gerhard Drolshagen, a physicist who specializes in near-Earth objects (NEOs) at the University of Oldenburg in Germany and who is the former director of the United Nations’ Space Mission Planning Advisory Group.
It entered Earth’s atmosphere going approximately 19 km per second, or 42,502 mph — an almost unfathomable 50 times the speed of sound.
Some smaller fragments also survived, which have been studied extensively, according to a report from the 45th Lunar and Planetary Science Conference in 2014.
But as we can see from the 190 known impact craters on Earth’s surface, some even larger meteorites have made it through our atmospheric “blanket” protecting the planet, and have caused untold damage.
The Earth Impact Database shows that of all those that are known to have hit the ground, most of the recorded meteorites have touched down in North America (32%), followed by Europe (22%) and then Russia and Asia (16%).
The largest three impact craters on Earth
Of the known impact craters, 44 measure 12 miles (20 kilometers) across or larger. The largest three to have hit either on land or water are the following:
1. The Vredefort crater in South Africa
At an incredible 99 miles (160 km) wide, this crater was likely created about 2 billion years ago, according to NASA’s Earth Observatory. Based on what’s left of the rim of the formation, scientists believe that the meteorite that caused it was 6 to 9 miles (10 to 15 km) in diameter, according to Chodas. “That’s bigger than the one that killed the dinosaurs, but long before dinosaurs,” he notes.
Drolshagen explained to Live Science “it is expected that if an object is bigger than 1 km (0.6 miles), it could have global effects.” That would certainly make the asteroid that created the Vredefort crater equal to the one that ended up killing the dinosaurs, Chodas states. “The impact would likely have caused fires all around the world, and a tremendous amount of dust would have been thrown up into the atmosphere” altering the climate up to years beyond the event, he noted.
2. The Chicxulub crater — formed by the infamous meteorite that killed the dinosaurs
Located on Mexico’s northward-curving Yucatan Peninsula, this crater is nearly the size of the South African formation, but it has of course gone down in history as evidence of the fateful event 66 million years ago which killed the dinosaurs that once dominated our planet.
It is of a similar size, at 112 miles (180 km) wide, according to NASA’s Earth Observatory, the handiwork of a gigantic meteorite that measured an incredible 7.5 miles wide (12 km) and which blasted down into the Earth’s crust to a depth of half a mile.
The crater is now partially on land, with most of it under the sea. The cataclysmic explosion, which hurled megatons of dirt and debris into the atmosphere, led to the extinction of 75% of the animal species that were alive at that time, including all the dinosaurs.
The airborne dust and debris blanketed the Earth for years, blocking out sunlight and almost wiping out the entire food chain of the planet. The flying dinosaurs, such as pterodactyls, which did survive the actual blast, most likely starved not long afterward, according to Chodas.
3. Sudbury Basin in Ontario, Canada — now an asteroid mine
This much-lesser known crater is the third largest crater on Earth and one of the oldest as well, at 1.8 billion years old. According to a study published in the journal Terra Nova in 2014, it may not have been a meteorite that created the gigantic crater but rather a giant comet, which consisted of a mixture of rock and ice.
Another giant amongst all the space debris to make it all the way through the atmosphere and hit the Earth, it measured between 6 and 9 miles in diameter.
Now, there is a prosperous nickel and iron mining industry in the Ontario crater. But there is an otherwordly aspect to this otherwide prosaic mining activity, because as Chodas notes “What they are really mining is leftover asteroids.”
Barringer Creater named after the man who created hypothesis of crater impacts
The Barringer Crater is not only of the largest craters of all but it has the distinction of being the first crater on Earth to be recognized as having occurred as the result of a meteorite. It is a very young crater, as these things go, created approximately 50,000 years ago in what is now the US state of Arizona.
Geologist Daniel Barringer, who lived from May 25, 1860 to November 30, 1929, was the first person to prove the existence of impact craters on the Earth. This spectacular site has now been renamed the Barringer Crater in his honor.
The crater, which almost looks like it was made yesterday because of the extreme dryness of the climate in Arizona, is a popular tourist attraction. There is a Meteor Crater Visitor Center on the north rim which displays a fragment of the original meteorite, which was found at the bottom of the crater.
The formation was made by a nickel-iron meteorite which originally measured a staggering 160 feet (50 meters) across.
More asteroids were “flying around” during formation of the solar system
Shaun Wright, a professor from Arizona State University, says of Barringer “Since it’s only 50,000 years old, geologically speaking, that’s like it happened yesterday. If this had occurred 100 million years ago, these rocks would be weathered and it would be harder to trace what had happened to them.”
The morphology of the area, with gigantic boulders that were thrown up from the depths of the earth dotting the crater, was even used by astronauts while training for their lunar mission back in the 1960s. Since they were not trained geologists, the crater was an invaluable resource in teaching them how to recognize the many geological features that are common to all craters, something that would stand them in good stead as they explored the Moon.
Despite the youth of the Barringer Crater, it is apparent to even casual observers that most such gigantic impacts occurred many eons ago, and that is indeed the case. As Chodas explains, “A lot of the big ones are really old, because in the early days of the solar system, there was a lot more debris flying around and impacts were happening much more frequently.
“You see the Moon covered with craters — the Earth would look the same if it weren’t for oceans and erosions,” he adds. Obviously our planet is pockmarked with craters from asteroid impacts, and there may well have been even larger craters formed than we cannot see today.
The Earth Impact Database shows that of the 44 largest craters that were formed from impacts from space rocks of all kinds, 39 of them were created more than 10 million years ago, with just one of them, Kara-Kul in Tajikistan, made less than 5 million years ago.
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