Hiroshima-Scale Explosions that Nobody Warns Us About, Occur Every Year in Earth’s Atmosphere

[Avi Loeb Medium]

An equal-area projection map of impact locations (red dots) for 343 meteors with known velocities and impact energies recorded in NASA’s Center for Near-Earth Object Studies (CNEOS) Fireball and Bolide Database from 1994 February 1 to 2026 January 1. The estimated diameter of each object (ranging from 0.75 to 24 meters) is indicated by the relative size of its dot. The spatial distribution of impacts over Earth’s surface appears nearly uniform. (Image credit: I. Cho et al. 2026)

Every year, an explosion with an energy output comparable to the Hiroshima atomic bomb occurs in our atmosphere without advance warning (as reviewed here). But in difference from the historic Hiroshima explosion on August 6, 1945, these annual explosions are not mentioned as breaking news because they involve a natural rock that measures a few meters in diameter which burns up in a fireball at an altitude of 30–50 kilometers. In contrast to the atomic bomb which was intentionally detonated 600 meters above the city Hiroshima in order to maximize damage, the high altitude of meteor explosions makes most of them unimpactful for life on Earth.

Nevertheless, under rare circumstances some small meteoritic fragments trigger reported damage on the ground once every few years. For example, on June 26, 2025 a meteorite, later determined to be from a one-ton, 4.56-billion-year-old rock, tore through the roof of a house near Atlanta. The fragment was small, about the size of a cherry tomato, but it left a hole in the roof, went through air ducts, and slammed into the concrete floor. In May 2023, a metallic meteorite, approximately the size of a grapefruit, crashed through the roof of a home, causing minor structural damage to the roof and floor but no injuries. Given that house cover only a small fraction of Earth, numerous such incidents must occur every year over uninhabited areas.

Those who worry about the risk of being hit by a cosmic impactor from the sky, might wonder whether we could receive an advance warning about this risk. After all, we are used to weather forecasts which warn us about the risk from droplets of rain falling from the sky. Could we imagine a future in which the daily forecast will also include a warning about a small meteor impact on a particular region? Obviously, no umbrella can withstand a meteor impact, but resident in the risk area might chose to leave the region in advance of the impact.

A new paper posted here, shows that the NSF-DOE Rubin Observatory will be able to warn earthlings about 1 in 25 of all imminent impactors larger than a meter, a few days in advance.

The paper simulated the expected discovery performance for imminent impactors using 343 meter-size objects previously recorded in NASA’s CNEOS database as fireballs in the Earth’s atmosphere. The simulations indicate that the Rubin Observatory will discover at least one meter-size imminent impactors per year, representing about 4% of all Earth impactors larger than a meter in diameter and almost doubling the current discovery rate of imminent impactors. The median time of discovery is 1.57 days before impact. The spatial distribution of the 11 previously discovered imminent impactors is biased towards the Northern Hemisphere, where the observatories that discovered them are located. By observing the southern sky, the Rubin observatory will provide an important counterpart to existing asteroid surveys which are primarily located in the Northern Hemisphere.

Aside from information about the Solar system, material falling from the sky could also educate us about the makeup of our neighbors’ yards. About one in a thousand impactors might be interstellar in origin.

Here’s hoping that among the interstellar meteors, we might find one day a Voyager-like meteor that was launched by an extraterrestrial civilization on the other side of the Milky-Way galaxy billions of years ago. Such an object would resemble an odd tennis ball that came from a neighbor’s yard. Meteor experts might respond to it like cave dwellers confronted for the first time with a cell phone, saying: “This is a rock of a type that we had never seen before.”

ABOUT THE AUTHOR

(Image Credit: Chris Michel, National Academy of Sciences, 2023)

Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.

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