When Galileo trained his telescope on the moon in 1609 and discovered that circular craters dominated its topography, astronomers began to wonder how they formed. Some astronomers, such as Franz von Gruithuisen, a German from the early 19th century, suggested asteroid effects as the cause. But most have rejected this theory on the basis of one simple, extremely confusing fact: the craters of the moon are almost perfect circles. And as someone who threw a rock into the ground can tell you, this is not what an impact scar should look like. Instead, the mark will be elongated, oval and tangled. (Gruithuisen probably did not help his case by also claiming that he saw cows grazing on moongrass in these craters.) Astronomers can further deceive any theorists, but can make up small mountains in the middle of every depression. Thus, for 300 years, the majority of astronomers and physicists believed that (1) cows did not graze on lunar pastures, and (2) lunar volcanoes, rather than meteors, packed its face.
Then, in the early 1900s, astronomers like the Nikolai Morozov of Russia* begins with the observation of newly developed high explosives and makes a rather astonishing discovery: large explosions differ in different ways from cast rocks, but the most ominous – at least for the survival of our species – leaves their circular craters, regardless of their angle of incidence. As Morozov wrote in 1909 after conducting a series of experiments, asteroid impact would “throw away the surrounding dust in all directions, regardless of their translational motion in the same way that artillery shells do when they fall on loose ground.”
Before Morozov was discovered, astronomers were aware that asteroids could be devastating. “The fall of a volcano even ten kilometers in diameter … would have been enough to destroy the organic life of the earth,” said Nathan Shaler, dean of Harvard’s Lawrence Scientific School and a proponent of volcanic theory. , written in 1903. But most believe it was a purely theoretical exercise, in part because, as Shaler noted in his defense of the lunar volcanism theory, the existence of mankind proved that this kind of impact could not occur.
Morozov’s calculations changed that. Once you know the origin of the scars on the moon, you do not have to be an astronomer – or even own a telescope – to come to the sobering conclusion that asteroids have apocalyptic potential and that the impact of which is inevitable.
Shaler was in a way exactly wrong. An asteroid of almost the size he described done impact Earth and done erases the planet’s dominant species. Rather than wipe out humans, it cleared the evolutionary path for a plasma mammal with a hedgehog to eventually crawl, walk, and consider a camping trip to the apocalypse.
You can think the survival of your prosperous ancestor proves that a mammal with a larger brain like you would have a reasonable chance. Unfortunately, the foreman had a number of apocalypse-friendly adjustments that people have since lost. The forefather was able to survive on insects, drilling away from the heat and having fur to warm himself during the frozen decade thereafter. You can repeat some of the patriarch’s survival strategies. You can expand and expand your diet. But evolution has robbed you of others, and your conflicting thumbs may not be enough to save you when that bright star enters the Earth’s atmosphere at 12.5 miles per second.
Against the impact of velocity, the Earth’s atmosphere behaves like water. Smaller rocks – called meteors – hit the atmosphere like pebbles in a pond; they decelerate rapidly at high altitudes, or burn away in their friction with the air or decelerate to their terminal speed of 164 km / h. But the mountain-sized Chicxulub asteroid hits our atmosphere like a boulder in a pond. It maintains its velocity to the impact and immerses in the entire atmosphere within 60 seconds. The asteroid screams across Central America and gives a sonic surge that echoes across the continents.
It falls so fast that the air itself cannot escape. Under intense compression, the air almost immediately becomes thousands of degrees. Before the asteroid even arrives, purple and overheated air evaporates much of the shallow sea that covers the Yucatán in the late Cretaceous. Milliseconds later, the remaining rock dives through and falls more than 10 miles per second into the rock. At that moment, some almost simultaneous processes take place.
First, the striking meteor exerts so much pressure on the ground and the rock that it does not shatter or disintegrate, but rather flows like liquids. This radical effect actually makes it easier to visualize the formation of the crater, because the undulations of the earth almost exactly repeat the double splash of a cannonball in a backyard. The initial splash in all directions is followed by a delayed, vertical coil when the cavity created by the impact bounces back to the surface.