Nobody is safe. Ever. Anywhere.
“The Day the Sands Caught Fire” is the title of an article one of us published in Scientific American in 1998 (Wynn and Shoemaker, 1998) about the Wabar asteroid impact event of 1863. This was a Hiroshima-explosion-sized impact in the middle of the remote Empty Quarter of what is now modern Saudi Arabia. As far as we know, no one died and nothing went extinct.
The Chicxulub Event about 65 million years ago, however, wiped out the dinosaurs. (Not all of them died, actually; modern-day birds, tortoises, and alligators, among others, are their direct descendants.) That Chicxulub object (there are still arguments about whether it was an asteroid or a comet) was about 10 km (6 miles) in size. The Wabar object was quite a bit smaller – about the size of a small house. It smacked down in the middle of the driest and hottest desert in the world (the temperature reached 610C (1420F) one mid-morning while I ran a magnetometer profile over the largest two craters (Wynn, 2002).
While small by comparison with the Chicxulub object, the Wabar object still caused startling damage. Geologic and geophysical mapping show that it raised a mushroom cloud to at least the stratosphere; molten glass rained down at least 850 meters (900 yards) away. The object apparently broke up in the lower atmosphere and created at least three craters that we could still see between the moving saif dunes (“saif” is Arabic for “sword,” and these dunes are called this because their top edge appears like a giant sharp blade sweeping across the desert). Calculations show that the asteroid (94 percent iron and 4 percent nickel, plus a little copper, cobalt, and iridium) brought with it a kinetic energy equivalent to, or greater than, the Hiroshima atom bomb. The Wabar impact site is similar in all ways to the Sedan and other medium nuclear bomb craters in the Nevada Test Site, save one: there is no residual radiation. There is shocked quartz, there is an asymmetric ejecta field, and there are other minerals that suggest temperatures momentarily reaching over 10,000 C. If you could have seen it happen, it would have been a magnificent sight – but you would likely not have survived the experience.
Here’s a crucial point: Wabar happened in 1863. Gene Shoemaker (the father of astrogeology) and I mapped the field site together and we made a bet. We both agreed that the site was very young, much younger than the ~6,200-year previous estimate from fission-track dating. During a raging sandstorm one night we collected sand unexposed to light since the impact on some 1930-era samples collected by Philby (Philby, 1933), from below the impact rim of one of the craters. If the Wabar site was older than a Qur’anic reference to a destroyed city named ‘Ubar, then I owed Gene a steak dinner. If it was younger than that, he owed me a Thai coconut sticky-rice dessert, and the dinner too, if he felt like it. Sadly, Gene was killed in a car-wreck 300 km north of Alice Springs in Australia in 1996, before the thermo-luminescence dating results came back. It turns out the impact site was less than 250 years old. Details for the 1863 date are in our Scientific American article (November 1998 issue; link above).
Whew. A “city buster” hit the Earth 150 years ago? Imagine that.
Another crucial point: I have partial records that suggest that at least FIVE “city busters” like this hit the Earth (Wynn, 2002a). There were impacts in 1863 (Wabar, Saudi Arabia), 1908 (Tunguska, Russian Siberia), 1930 (Río Curacá, Brazil-Peru border), 1935 (Rupununi, British Guyana), and in 1947 (Sikhote-Alin, Kamchatka, Russian Far East). At least five times in a century these huge kinetic-energy bombs have crashed into the Earth – and that’s just on the 29% of it that is on land that we can see evidence for (https://water.usgs.gov/edu/earthhowmuch.html). Fortunately, every one of these fell in very remote areas. I published another article in 2002 (Wynn, 2002b) that showed that these things happen far more frequently than even a radical like Gene Shoemaker had suspected.
Over one-third of the total human population, nearly 2.4 billion people, lives within 100 km (60 miles) of an oceanic coast (https://science.nasa.gov/earth-science/oceanography/living-ocean). The reason? Because the weather is more moderate near an ocean. Remember that at least 71 percent of the Earth’s surface is ocean. Something like 20,000+ tons of TNT equivalent detonating under an ocean is a near-perfect tsunami-maker, comparable to tsunamis generated by subduction earthquakes. If the hit centered on your city, it would mean a relatively clean death by comparison to everyone around it.
One final point: We cannot easily “see” these things coming. They have to be really big before enough light scatters off them to be picked up by Earth-based telescopes, and you would need many “picks” before you could calculate a reliable orbit. By the time you could actually see a Wabar-sized object coming, it would already be over. Since the Earth has substantial gravity, one of these things flying even close to the planet will be drawn towards us, gravity being what it is. We can’t use radar to spot these things, either. The energy of a radar beam falls off as the distance squared, and even if the beam was 100 percent reflected, the reflected beam would have only the energy reflected, and then that falling off as the return distance squared. Mankind doesn’t have radar systems with enough energy to do this; if we did, it would fry everything in the sky flying through its beam.
What does this all mean? It means we are helpless beneath the sky. It means we do not control our future. You can get fairly good warning of a volcanic eruption, but a supervolcano the size of Yellowstone (United States), Toba (Indonesia), or Veniaminof (Aleutians) going off could still take the few survivors on our world back to the Stone Age. We can get a shorter warning for a hurricane, a really short warning for a tornado, and just seconds to minutes warning for a subduction mega-earthquake – or for one of these bombs from the sky.
But you can store a year’s supply of food and water with the intent to help your family and your neighbors survive a near hit. If you do that for your whole neighborhood, you can reasonably call yourself a Christian – being Christ-like. This is the real reason behind why members of the Church of Jesus Christ gather a year’s supply of food and water: to be Christ-like and take care of their neighbors, as well as themselves, in case of a disaster.