Welcome to Everyday Science with Clare Wilson, a subscriber-only newsletter from The i Paper. If you’d like to receive this directly in your inbox every week, you can sign up here.
Hello and welcome back to Everyday Science! I have some exciting news to share. The odds of a giant asteroid, known as Asteroid 2024 YR4, impacting Earth in 2032 have dramatically decreased. Last week, the European Space Agency estimated the chances at about 3 percent, but this has now plummeted to a mere 0.002 percent. While we breathe a sigh of relief regarding this particular space rock, many of my friends have been curious about the fluctuating odds and humanity’s potential responses. Let’s dive into these questions and more!
Why Do the Odds of an Impact Keep Changing?
Asteroid 2024 YR4 is a relatively recent discovery, detected just two months ago by an automated system at a telescope in Chile. Initially, it was thought to pose a small threat to Earth. However, as more telescopes around the globe began to observe it, more data points were collected, allowing scientists to refine its orbital path. According to Professor Danny Steeghs, an astrophysicist at the University of Warwick, “In those first few weeks, you’re only covering a small section of its orbit. At that point, there are significant uncertainties. Rather than providing a specific trajectory, scientists produce a distribution of possible trajectories. The calculation of how many of these paths intersect with Earth leads to the quoted probabilities. Frequent recalculations are performed whenever new data points are gathered.”
Could the Risk Increase Again?
Fortunately, a resurgence in risk is considered “highly unlikely,” according to Professor Steeghs. The asteroid is currently moving away from Earth, and additional data collection will be impossible until it re-approaches in June 2028. Thankfully, enough observations were made recently to alleviate concerns for the next three years. “We have gathered sufficient data over the past few weeks that more alarming scenarios are now improbable,” Professor Steeghs reassures. “The likelihood of the risk rising again is virtually non-existent.”
If the Risk Had Stayed High, What Would Have Happened Next?
In recent years, preparations for detecting and responding to potentially hazardous asteroids have been ramping up. Various organizations, including NASA and the European Space Agency, have established plans. Actions would depend largely on the size of the incoming asteroid. Asteroid 2024 YR4 is estimated to be between 40 and 90 meters in diameter—considerably smaller than the asteroid that contributed to the extinction of the dinosaurs, which was about 10 to 15 kilometers wide. However, a collision with YR4 could still result in significant destruction, particularly if it were to land in a populated area. The impact’s severity would hinge on its exact size.
If it were 40 meters wide, it would be twice as large—and eight times the mass—of the meteor that exploded over Chelyabinsk, Russia, in 2013, which caused damage but no fatalities. Conversely, if it were 90 meters wide, it could be classified as a “city killer.” In March, NASA will utilize the remarkable James Webb Space Telescope to study Asteroid 2024 YR4, providing more accurate measurements of its size and allowing us to better understand our potential responses, even though the current outlook appears promising.
How Could We Stop an Asteroid?
While movies like Armageddon depict heroic teams detonating nuclear bombs on incoming asteroids, in reality, such actions would be considered unwise, according to Professor Steeghs. “You’d likely break one large rock into several smaller pieces, which could cover a much larger area upon impact than the original asteroid would have,” he explains. Instead, the most viable strategy is to deflect the asteroid from its trajectory. Possible methods include crashing a spacecraft into the asteroid, using lasers, or applying a reflective material that could redirect sunlight, providing a gradual push over time.
The more advance notice we have, the less forceful the nudge required. The asteroid’s composition is also a critical factor; if it is fragile, a strong impact could cause it to break apart. “You can’t predict whether there are fissures within the asteroid that might result in fragmentation,” cautions Professor Martin Ward, an astrophysicist at the University of Durham. Three years ago, NASA conducted its first mission aimed at altering an asteroid’s course by colliding a small probe with an asteroid named Dimorphos. The mission was successful, as the impact changed its orbital path—though more significantly due to the asteroid ejecting a cloud of dust. “The outgassing contributed more to the deflection than the initial impact,” Professor Steeghs noted.
This experiment has led to the exploration of a new deflection technique that involves deliberately causing outgassing by damaging the asteroid’s surface. “This method allows for more control, as you can manage the process until the desired outcome is reached,” Professor Steeghs adds.
What Else I’ve Written Recently
If you’ve seen recent headlines suggesting that antidepressants may accelerate dementia progression, there’s no need to panic. Researchers, along with various experts, emphasize that the effects are not yet substantiated and, if they exist, would likely be too minimal to be of significant concern.
I’ve Been Reading
One of my favorite popular science authors is Mary Roach, an American writer whose work often blends biology with humor. I recently discovered her 2021 book, Animal Vegetable Criminal, which explores the myriad ways in which wildlife and humanity intersect. Roach’s quirky stories are filled with gentle wit and insightful observations about animal behavior, making them perfect for my evening reading.
