A June 2025 article published by LiveScience claimed that a “swarm of ‘city killer’ space rocks, known as co-orbital asteroids,” pose an “invisible” threat to Earth. These asteroids are found alongside another planet or large body, but they actually orbit the sun, not the celestial body. There are 20 of these asteroids currently found around Venus, and some of them are large enough to pose a real threat to Earth, especially if densely populated areas are impacted. The fear, according to the article, is that if one of these asteroids were to pass close to the Earth, our gravitational pull could pull the asteroid toward us on a disastrous collision course.
Despite overhyped claims by tabloids that Earth could be impacted by a Venusian asteroid “within weeks,” the article assures that “there is no immediate danger to our planet.” Such publications are not unique; if it’s not space rocks hiding out behind Venus, biding their time to decimate the Earth, its asteroids like 2024 YR4, which is reportedly poised to impact the Moon and shower Earth with “‘bullet-like’ meteors.” The widespread use of terms like “city-killer” to describe these asteroids also heightens the public’s anxiety about their potential impact, no doubt a clever ploy by some publications to drive up headline clicks.
Nearly all of these publications, however, assuage their readers’ fears by assuring that the objects pose no immediate threat to Earth, much like the publication put out by LiveScience.
Even 2024 YR4, discovered in 2024 and described by some media outlets as a “giant asteroid the size of the Statue of Liberty,” was believed to have a small (about a 1.3%) chance of impacting Earth in 2032. The risk corridor reportedly stretched from the eastern Pacific Ocean to South Asia, including densely populated centers like Bogota, Colombia, Lagos, Nigeria, and Dubai. However, NASA scientists have since stated that the object poses “no significant impact risk to Earth in 2032 and beyond,” and claim the chances of the asteroid colliding with Earth are practically zero.
Similarly, the asteroid Apophis—named after the Egyptian deity who embodied chaos and darkness—made headlines as a “potentially hazardous” NEO that will come close to Earth in 2029. Scientists have assured the public, however, that Apophis poses no threat to our planet, and Apophis will safely pass us—albeit at a closer distance than many satellites that are currently in geosynchronous orbit with Earth.
If so many of these objects are found to pose no threat to our pale green dot, why do we study NEOs?
Asteroid research itself is pivotal in our understanding of the solar system and how it formed, and could influence what we know about climate change and neighboring planets like Mars, which human settlers could one day call home. Knowing how Earth came to be could also provide insight on how we find another planet in a different solar system that could support human life.
Some of the most influential scientists in this area were Eugene Shoemaker and his wife, Carolyn. Carolyn was one of the most prolific discoverers of comets in her time. The Shoemakers were proponents of the idea that asteroid impacts could drastically transform Earth’s landscape and life itself, which at the time was regarded as a major rejection of uniformitarianism.
The Shoemakers would become influential in the effort to prevent asteroidal collisions with Earth. The Shoemaker-Levy 9, discovered by the duo, was found in 1993. In 1994, that same comet would collide with Jupiter; a massive event in the scientific community. The impact, detected by the Galileo spacecraft, was the first time human beings directly observed extraterrestrial objects colliding. Researchers knew that the comet would collide with Jupiter when it was calculated that it would pass within 28,000 miles (45,000 kilometers) of Jupiter’s center, meaning it was highly likely a collision would take place.
The impact of Jupiter proved that the planet serves an important role in the protection of inner planets in the solar system; its massive gravitational pull attracts many small comets and asteroids that might otherwise make their way towards Earth.
Beyond that, we know that the damage due to asteroid impact can be catastrophic to life on Earth, and no example is as effective as that of the Chicxulub crater.
Approximately 66 millions years ago, an asteroid measuring about six miles in diameter (ten kilometers) struck Earth. It left a massive crater approximately 120 miles (200 kilometers) in diameter and 19 miles (30 kilometers) deep. What’s left of the crater is not visible on Earth’s surface and is buried beneath the Yucatán Peninsula in Mexico.
The devastation left in its wake was immense; the impact produced about 72 teratonnes of TNT. For comparison, the atomic bomb the United States used to decimate Hiroshima, Japan in 1945 yielded about 16 kilotons of TNT. The impact produced a massive cavity measuring 62 miles (100 kilometers) wide and 19 miles (30 kilometers) deep, that later collapsed, producing megatsunamis with massive, nearly mile-high waves. The impact also produced winds exceeding speeds of 620 miles per hour, carrying a cloud of hot dust, ash, steam, and as much as 25 trillion metric tons of material that were ejected from the impact site. Wildfires caused by the impact (exactly how the wildfires came to be is still poorly understood) affected the majority of Earth’s forests, disrupting the food chain on a scale not before seen.
The Chicxulub impact wiped out approximately 75% of all of Earth’s species. Were it to happen today, the devastation would be monumental, and it’s uncertain if human beings would survive. If they did, their existence on Earth would be heavily compromised.
The threat of NEOs looms large, but the study of their existence is a relatively young science. Research on near-Earth objects, or NEOs, can be traced back to the 2013 fall of the Chelyabinsk meteorite in Russia. The object is believed to have been about 65 feet (20 meters) in diameter; the fireball entered Earth’s atmosphere and exploded at an altitude of approximately 23 meters, releasing about 500 kilotons of TNT. The explosion caused injury to about 1,500 people, and the subsequent shockwave caused windows to shatter and other structural damages to buildings in the area.
The preceding largest NEO airblast was the 1908 Tunguska event. Little data is available from the explosion, due to the event’s remote location in the Siberian forest. The cause for the explosion is attributed to a meteor airburst; the asteroid was believed to be about 160-200 feet (50-60 meters) wide. The destruction was extensive and affected 830 square miles (2,150 square kilometers) of forest, felling millions of trees. According to eyewitnesses, three people may have died, though this is unconfirmed.
While the Chelyabinsk event didn’t result in any fatalities, the prevalence of dashboard cameras among Russian citizens resulted in an unprecedented circumstance: the capture and broadcast of an NEO event. Spurred by these impacts, NASA established the Planetary Defense Coordination Office, whose objective It was to conduct research on NEOs and devise strategies to mitigate their effects.
For comparison, the two largest California wildfires, the 2020 August Complex Fire and the 2021 Dixie Fire, burned 4,170 square kilometers and 3,890 square kilometers, respectively. Notably, while these fires obliterated the landscape, the August Complex Fire claimed the life of one firefighter while the Dixie fire had no official death toll. Were an NEO to collide with Earth, millions of lives would be at stake.
Research on NEOs also includes prevention methods. The aptly-titled “National Near-Earth Object Preparedness Strategy and Action Plan” identifies these prevention concepts as kinetic impactors, nuclear devices, and gravity tractors. The Double Asteroid Redirection Test (DART) was one of NASA’s missions meant to test an asteroid deflection method whereby a spacecraft could deflect an incoming asteroid by crashing into it. In theory, the transfer of momentum could be significant enough to throw the asteroid off-course. DART, conducted in 2021, successfully collided head-on with Dimorphos, a minor-planet moon of the larger asteroid Didymos. The DART spacecraft collision shortened Dimorphism’s orbit by 32 minutes, and is considered to have been highly effective in deflecting Dimorphos.
NASA isn’t the only agency working on planetary defense strategies. China’s first mission to impact an asteroid is planned sometime before 2030. The mission’s target is the 2015 XF261 asteroid, which measures nearly 100 feet (30 meters) wide. A recent paper published in the Journal of Deep Space Exploration states that the mission’s aims are two-fold: to examine the space rock and learn more about the solar system and its origin, and to impact the asteroid and hopefully disrupt its trajectory.
While it’s not certain when another catastrophic asteroid impact event might happen, it’s almost certain that one will occur again. Headlines about NEOs on a crash collision course with Earth may be irritating now, but they won’t always be so benign. Sooner or later, Earth will undoubtedly face the threat of another asteroid impact, perhaps one as large as the one that caused the Chicxulub event; humans will need to keep their eyes to the skies, and be prepared.
