That width is less than the distance I drive from my house to the grocery store. Why was that size of an asteroid able to cause such catastrophic damage?
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Its not necessarily about the impact but the consequences of it.
One event can trigger volcanos to errupt, this leads to huge clouds of dust which will take months or years to vanish. This will cool down earth, killing plants and trees and basically food for animals. Its a cataclysmic chain reaction.
Size isn’t the only part of the equation that matters though. A bullet is very tiny. However, if the bullet is moving very fast, it will have a lot of force when it hits your body.
In this case, the combination of the speed and size of the meteor was enough to blast tons of dirt and dust into the air. It basically covered the world in darkness, because not as much light could get through this dusty smoke that was covering the entire planet. And most of the plants on the planet died because they couldn’t get enough sunlight anymore. And the very large dinosaurs starved to death because they needed tons and tons and tons of food to survive, while smaller animals were able to survive because there were still enough plants that they could find what they needed to eat.
Our estimates are that the dust cloud created by the meteor impact would have lingered in the sky for over a year. Long enough, that many plants just died, and even more animals that were depending on those plants died too.
The dinosaurs being so big was sort of what doomed them.
You have a huge amount of kinetic energy. Like with a nuclear explosion but scaled up incredibly it threw millions of tons of debris into the air. The bigger pieces of debris quickly fell back onto the earth creating other smaller impacts. The sheer friction of all those pieces reentering the atmosphere heated the planet up like an oven so much of the surface was literally cooked. Then the smaller particles from the initial impact lingered creating a long, long winter and it blocked out the sun. This causes plants to die off.
There have been times that a big volcanic eruption caused mild global cooling for a short period of time. But the asteroid impact 65 million years ago was vast compared to a single volcanic eruption
Imagine an explosion so big that it is able to instantly vaporize both your house and your grocery store and turn all the air into super hot plasma. Just imagine how much destruction that would cause on the rest of the city and surrounding area. That is what happens when a meteor hits the atmosphere. But unlike an explosion which only takes a fraction of a second the meteor will continue to output that amount of energy all the way down through the atmosphere for minutes sending out shock waves and super hot plasma in all directions. And that is only as it descends down the atmosphere. When it hits the ground the impact is going to cause even bigger shock waves through the earth and turn the bedrock into hot magma. It will force the earth to bend out of the way from the impact. Your house and grocery store would only be at the center of the devastation, the bedrock under your feet would need to go somewhere, and the rocks it displaces would need to go elsewhere.
There have been a lot of studies done in the past few years concluding that this was not the only big impact around that time period; that there were other meteor/asteroid impacts of similar or even bigger size within a short time frame around that one.
Kinetic energy is 0.5mv^2, so is proportional to mass. Double the mass, double the kinetic energy.
Kinetic energy is proportional to the square of velocity. Double velocity, quadruple the energy.
Objects in solar orbit are generally going very very fast with respect to earth. So even an object with small mass has tremendous kinetic energy.
For example, the object that struck the Barringer crater in Arizona was only about the size of a 747 in terms of radius (but was much more massive being a non-hollow rock). https://en.wikipedia.org/wiki/Meteor_Crater?wprov=sfla1
That object struck with so much kinetic energy that the entire object not only _melted_ from the heat but _evaporated_ from the heat of the impact. So a hunk of iron bigger than a 747, at the moment of impact, turned into iron _gas_. Gases take up a lot more volume by mass than liquids and solids. Gases approximately follow the ideal gas law, PV=nRT, at any given moment. So at the moment of impact, temperature T spiked enough to turn solid iron into gas iron. So the left-hand side of this equation suggests that either pressure P or volume V had to spike also. But at the precise moment of impact, the meteor still occupied almost the same volume as the moment before. So it must have been pressure that spiked. So, the gas expanded explosively. By turning from a solid to a gas at the moment of impact, the meteor basically exploded into a huge cloud of iron gas.
As it expanded, the gas iron cooled into molten iron, which rained down for miles around the impact site.
Now apply the same thing to an object several miles across, and you get an event that shakes tectonic plates and lays down a layer of metal across the entire surface of the planet. The layer from the dinosaurs’ extinction event is known as the KT boundary.
> That width is less than the distance I drive from my house to the grocery store.
Phrasing it that way makes it sound small, but you could also phrase it as “If you gently set the asteroid on the Earth’s surface at sea level, its top would reach up higher than the tallest mountain range on the planet.” Imagine Mount Everest, but bigger, and then imagine it’s moving towards you at the speed of a rifle bullet—*except it’s actually moving twenty times faster than that.* It’s moving so fast it passes from the top of the atmosphere down to sea level in less than ten seconds.
Having decent estimates for the size and mass of the asteroid, it’s simple to calculate the amount of energy it delivered to the impact site using Ek=1/2mv^(2). Taking a low estimate of 4×10^15 kg and 20 km/s, the impact released 8×10^23 Joules of energy, the equivalent of almost two hundred million 1-megaton nuclear bombs piled up in one spot and detonated simultaneously.
The escape velocity of earth is 11km/s which is the lowest speed an object can hit earth if you ignore the atmospheric drag, On average the speed is 18km/s but it can be as high as 30km/s
The kinetic energy is E=m v^2 /2 where m is the mass in kg and c v the speed in m/s. TNT release released 4.6 million joules when it detonate. so if we solve 4.6 *10^6 =v ^2 /2 we get the speed when kinetic energy is equal to the explosive energy of the same amount of TNT. The answer is v=30m/s = 3km/s.
so the slowest impact is 11/3 = 3.6 time faster and the kinetic energy is 3.6^2 = 13 times larger. So the slower possible meteorite has the same energy as 13 it’s mass in TNT
What is the mass of a 10-15km asteroid? Let’s use a sphere with a 5km =5000 m radius. The volume is 4/3 pi r^3 so the volume is 5.2 * 10^11 cubic meter. Rock has a density of around 3 tonnes/m2 so the mass is around 1.5 * 10^12 tonnes. Multiple by 13 and we get the energy in tonnes of TNT 19.5 * 10^12 tonnes of TNT
Nuclear bomb yields are in tones of TNT and 1 megaton =1 million tonne = 1 * 10^6. This means the energy in the meteorite is more than 19.5 * 10^12 / 1 * 10^6 = 19.5 * 10^6 = 19.5 million atomic bomb with a 1 megaton yield. 1 megaton is a large strategic nuclear weapon that can destroy a city. The total energy in all nuclear weapons on is equal to around 3 000 1 megatons of bombs so we talk about 6500x more energy realized at once in one location This is a minimum energy calculation
I you look at the number from Wikiepada the estimated impact speed is 20km/s and 100 million 1 megatonne nukes.
It is the global fire storms and all the particles that then will be on the atmosphere and result in global winter a couple of years long when practically no sunlight reaches the ground that killed the dinosaurs and most other life on earth. Technically all dinosaurs did not die, birds are dinosaurs and their ancestors did survive.
Dinosaurs were stressed and losing species millions of years leading to the impact, which caused a huge tidal wave and severe climate change.
Some dinos survived and became Avians, so not totally wiped out.
the asteroid hit really really hard. 1 billion nuclear bombs going off at the same time. The heat from the explosion cooked everything around it. Then extremely hot rocks and boulders that bounced into the sky from the impact rained back down as lava bullets. These lava bullets were able to rain back down from very far away from impact. Another thing that rained back down was extremely hot ash that spread very far and suffocated life and caused wild fires. This ash combined with rain water in the clouds and rained back down as acid. The oceans became acidic killing marine life dust from the impact blocked out the sun and caused a cold winter
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