Meteor Crater
Credit: Wikipedia photo by Shane.torgerson, CC BY 3.0.

Aerial view of Meteor Crater, which is about one mile (1.6 km) in diameter.[1] The parking lot and visitors center area can be clearly seen in the lower left.

Known as the best place to see where a meteor struck the Earth

It should actually be called "Meteorite Crater," since the term "meteorite" refers to a rock that is on or in the ground already, whereas a "meteor" is a rock that's still flying through space or through our atmosphere.[2]

If we want to be even more technical, it was actually caused by an asteroid and not a meteor. Meteors are by definition 10 meters (33 feet) or less in diameter, and the object that struck the Earth at this location tens of thousands of years ago was more like 45 meters (150 feet) across, clearly meeting the size requirement for being called an asteroid. And the more technical name for these craters is “impact crater.”[2][3]

Meteors and asteroids come from the materials that formed the planets, moons, and other entities (comets, asteroids, etc) in our solar system 4.5 billion years ago. Many originate in the asteroid belt between Mars and Jupiter, and sometimes they get knocked out of orbit and come over toward Earth.[2][3]

Lots of small meteors burn up in the atmosphere of the Earth every day, but big ones that can cause an actual crater to form in the ground are a lot less common. Also, the Earth's surface is 71% ocean, so a lot of meteors and asteroids never hit the land surface of the Earth, because they're more likely to splash in the water somewhere.[2][4][5]

Another factor reducing how many impact craters we see on the Earth's surface is erosion. Wind and especially water can wipe out craters, especially in areas such as rainforests. The best places a crater might form and be visible for a long period of time (tens of thousands to hundreds of millions of years) are a desert areas with little precipitation, or a very hard rocky surfaces that don't easily wear away.[4][5]

One final factor in impact crater disappearance on Earth is plate tectonics, which don't exist on the other planets in our solar system. Over tens or hundreds of millions of years, an impact crater might be eliminated due to movement of the plates, which the Earth's crust is divided into. For example, one plate could over time subduct underneath another. Also, earthquakes and volcanic eruptions can erase signs of impact craters.[4][5]

Meteor Crater at ground level
Credit: Wikipedia photo by Alan Levine, CC BY 2.0.

Ground level view of the crater, from the rim. The crater is about 600 feet (180 meters) deep. I've walked all the way around it, an easy hike of about three miles (5 km).[1]

Arizona's awesome meteorite crater

Meteor Crater is also called Barringer Crater. It is located about 40 miles (65 km) east of the town of Flagstaff, and has a visitors center and a gift shop and a platform you can walk out, plus you can walk the three miles (4.8 km) all the way around the crater rim.[1]

I’ve been to this one and walked all the way around it. The crater was created about 50,000 years ago, when an asteroid estimated at 150 feet (45 meters) across slammed into the Arizona desert. This was right in the midst of the most recent ice age, which came to an end about 11,700 years ago.[1][6]

At the time the impact occurred, the Colorado Plateau (the physical feature where the meteor hit) was cooler and damper than it is now, more like grasslands than desert, and would have had animals like woolly mammoths, American lions, American cheetahs, saber-tooth cats, and giant ground sloths, although probably not any humans.[7]

The impact is thought to have been the equivalent of 150 times the force of the nuclear weapon dropped on Hiroshima, Japan during World War II. Modern nuclear weapons are much more powerful, although the energy released in this impact was still greater than two modern nuclear bombs.[1]

Another way to view the force of the impact that created Meteor Crater is that it is the equivalent to the amount of energy released in a 7.3 earthquake – although rather than being released deep in the ground over a minute or more, as in an earthquake, it was an instantaneous explosion on the surface.[8]

It was a man named Daniel Barringer who first suggested the crater was caused by an asteroid striking the Earth, and not volcanic activity as had previously been supposed. This original guess, that it was a volcano, was not bad because known volcanoes exist in Arizona near Flagstaff, one of which erupted less than 1,000 years ago.[1]

The impact crater hypothesis was proven to be correct in 1960 by Eugene Shoemaker, who discovered rocks in the crater that cannot be created through volcanic actions, but only under the enormous pressure of an asteroid striking the Earth.[1]

The present day crater is about 4,000 feet (1,200 meters) across and 600 feet (180 meters) deep from the rim, and the rim stands about 150 feet (45 meters) above the surrounding desert landscape. The crater is often said to be the very best-preserved of any impact crater on Earth, with few on Earth, of about 170 known, comparing.[1]