“Don’t Look Up” (2021), “Moonfall” (2022), “Armageddon” (1998) and “The Good Dinosaur” (2015) all share the same central character: an asteroid. Last month, it seemed as if Earth’s own story would soon be introducing a new guest.
Asteroid 2024 YR4 was first discovered Dec. 27, 2024, by ATLAS, a NASA-funded telescope.
ATLAS, the Asteroid Terrestrial-impact Last Alert System, scans the sky every single night looking for potential celestial assailants. The telescope entered public consciousness in August 2024 when it spotted asteroid 2024 PT5. This mini-moon sojourned around the Earth for a couple of months before reembarking on its journey into deep space.
Millions of asteroids meander throughout our solar system, a majority of which congregate in the asteroid belt between Mars and Jupiter. Rarely does a large asteroid ever hit our Earth.
Thomas O’Grady has been an observational astronomy instructor at Ohio University for over 30 years. He explained the nature of asteroids in relation to Earth.
“They say something like almost 50 tons a day of meteorite material enters the Earth's atmosphere and makes it to the earth surface,” O’Grady said. “(A lot) of them are tiny things, but they add up because they're always coming in.”
Occasionally — about every 1,000 years — problems occur when these “things” aren’t as tiny.
“We probably cross the path of orbits all the time, but if the asteroid isn't anywhere nearby when we cross the path, that's like crossing the street when the car is three miles away, no big deal,” O’Grady said. “But, if you cross the street when the car is 10 seconds away, you better watch out.”
The case of 2024 YR4 was different from the visiting mini-moon. Early last month, a stream of articles were released warning of an impending crash and dated for December 2032. Estimated to be about 180 feet across, the asteroid is not large enough to create a mass extinction event, but big enough to do some serious damage.
With a 2.3% chance of collision, the asteroid was deemed a “city-killer” by science websites. Magazines theorized where the asteroid could hit, and mass media outlets kept the public updated with each shift in its path.
Then, the chance of impact dropped to near-zero thanks to further investigations by NASA’s research team at the Center for Near-Earth Object Studies.
Now, with only a 1 in 120,000 odds of impact, asteroid 2024 YR4 has become yesterday’s news. Although this event may seem out of the blue, it actually happens semi-frequently, and when it does, it is usually big news.
Everyone knows about the “big one,” as O’Grady refers to it, which happened 66 million years ago and wiped out the dinosaurs. Yet, there have been others throughout history that have made a big splash (sometimes literally) around the globe.
“The Tunguska event in 1908 knocked some guy out of his rocking chair on his front porch hundreds of miles away,” O’Grady said.
In remote Siberia, the explosion flattened 80 million trees. Residents, as far as 20 miles away, felt the Earth shake and heard the thunderous impact of the asteroid. It took two decades for an expedition to reach the impact site.
In February 2013, an asteroid exploded over Chelyabinsk, Russia. This event was captured on cameras around the city, including on car dash cams. The blast injured around 1,500 people.
In 2024, a meteor lit up the skies over Portugal and Spain. Thought to be a piece of comet gone rogue, videos of the spectacular event went viral on most major social media platforms.
It is clear that reactions to asteroid events have changed over the last century. What once took decades to study is now monitored in real time, millions of miles away from the Earth.
“Serpent Mound is the largest serpent effigy built anywhere on the planet Earth,” O’Grady said. “Serpent Mound is built up on top of a bluff, and the reason that bluff is there, it's part of the impact from a meteor 250 million years ago. It's been being eroded ever since then.”
Serpent Mound is located southeast of Hillsboro, Ohio, an hour outside of Cincinnati. Geologists continue to study the large impact crater to learn more about Earth’s history.
Our Earth is shaped by the impacts of million-year old meteors and asteroids. It is not often that the planet is threatened by a “city-killer,” but the possibility remains ever-present.
NASA’s Double Asteroid Redirection Test mission successfully altered an asteroid’s path in 2022, proving that planetary defense is possible. DART, and other efforts, ensure that if an asteroid like 2024 YR4 approached the planet, we wouldn’t be left scrambling for solutions.
For now, 2024 YR4 is just one of the millions of space rocks drifting through the void.
