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The deserted metropolis waited for the asteroid to strike. A giant space rock entered the atmosphere, heading straight for the eastern seabboard of the USA. As it comes through the atmosphere, we would see something as bright as the sun getting brighter and at speeds of maybe 20 km/s or so. That's something like 18 times faster than the speed of a bullet coming out of a rifle. This asteroid was headed towards the most populous city in America. And when it impacts, it would deliver more energy than a thousand Hiroshima nuclear bombs.
It would level some of the most expensive real estate in the world in seconds. There would be a crater where Central Park used to be. I actually don't even like thinking about this of how horrible it would be. This is beyond the worst disaster the world would have ever faced. There's nothing in our history that would have done this much damage so quickly and so devastatingly. The story of the asteroid and the Earth's fight back started 7 years ago here in Arizona. the Catalina Sky Survey. Guardian of Heaven's Greg Leonard drives to Mount Lemon Observatory near Tucson.
He's on the hunt for asteroids and comets. We are the Watchers of the Skies for the planet. We literally represent the first line of defense against potentially incoming asteroids. And I want to emphasize the words planetary defense. This is not in the benefit for one nation. This is for the entire planet. Greg takes a series of images over a 20inut period. Stars don't move in the photos, but asteroids and comets do. Aha. We can see four points of light tracking across the background of the stationary stars. This one is moving very quickly across the sky. So, this tells me this is a real near-Earth asteroid candidate.
It's one of over 27,000 near-Earth asteroids, or NEAs for short, discovered by the early 2020s. The huge gravity of Jupiter can rip space rocks from their home in the asteroid belt. Some race outwards away from the sun. NEAs head inwards, occasionally towards Earth. We didn't know it back in September of 2022, but these were our first images of a deadly incoming asteroid. It's relatively close to Earth's neighborhood. We don't know exactly how far it is yet, but it's close enough where its motion across the sky appears rapid.
The discovery of an NEA set a series of planet protection protocols in motion. Step one, enlist a global team of experts to investigate the asteroid's orbit. We had some of the brightest minds, some of the best telescopes, some of the biggest supercomputers working to protect Earth, collaborating across language barriers, across international borders to protect humanity. This International Planetary Defense Team was tasked with discovering if the distant object would become a serious threat to Earth.
Their first job, determine if the NEA's orbit would intersect with our own. Orbits are a little like roads, right? You've got a path that something follows and they can intersect. You can have a crossroads. Now, typically, if only one object is there, that's not a big deal. But if you have two objects approaching that intersection at the same time, they could collide. And that's the danger from asteroids. The team of scientists tracked the asteroid for 4 months. Over time, you can build up observations. You can gradually narrow down the possible number of orbits. Then determine whether there's any chance of a future impact. But the asteroid is orbiting the sun.
The Earth is orbiting the Sun. And there's this dance going on. Sometimes the asteroid is near the Earth and we can observe it. It's bright. Other times the asteroid is on the other side of the sun. We can't observe it at all. We were lucky. The asteroid was visible throughout the fall of 2022. However, our observations of the space rock's orbit showed a very real possibility that it would slam into Earth in just 7 years. Astronomers gave the incoming asteroid a suitably appropriate name, APEP. APE was the Egyptian god of chaos. So that's a fairly good name for an asteroid that could hit the Earth because that's exactly what would happen. You would have chaos,
destruction, and death. A catalog of devastation to be unleashed on Earth. But just how bad would the impact be? January 2023. Asteroid APE was on a collision course with Earth. Step two in our planetary defense. Know your enemy and build up a picture of the asteroid. APE was 1,800 ft wide, five times the length of a football field. Its huge size bumps it up into a new category of asteroids.
APE was what we refer to as a PHA, a potentially hazardous asteroid. We're talking about something that is a third of a mile across. This is enormous. An 1800t wide asteroid is about 112 million metric tons. That's over 300 times the weight of the Empire State Building. Computer simulations of the impact of an asteroid that massive hitting a city revealed extraordinary levels of destruction. An 1,800 ft diameter asteroid that would create uh a crater that's 3 or 4 miles across um 1,600 ft deep. It would have a radiation blast wave that would set things on fire for about 20 miles. But no sooner would things be lit on fire.
There would be a 500 mph wind radiating out, leveling buildings, knocking down trees, destroying highways. 100 miles away, you'd still feel a magnitude 7 earthquake. It's not easy to say what is going to kill you first. It's probably going to be simply the flash of energy. There's so much heat from this thing that you can be vaporized. If you somehow survive that, then there's going to be the blast wave that will pulverize anything in its path.
