What are the odds of dying from an asteroid or comet impact?
Evidence quality 4.75/5
Eight-dimension review score against the quality rubric . Each dimension scored 1–5.
- D1 Source grounding
- 5/5
- D2 Source authority
- 5/5
- D3 Arithmetic
- 5/5
- D4 Uncertainty
- 5/5
- D5 Scope
- 5/5
- D6 Prose
- 5/5
- D7 Perception honesty
- 3/5
- D8 Caveat completeness
- 5/5
Lifetime probability · lifetime, global adult
1 in 1,351,351
0.00007% lifetime chance
Most people overestimate this.
range 1 in 10,000,000 to 1 in 166,667
≈ As likely as
Perceived
Asteroid impacts occupy a peculiar slot in the public imagination: simultaneously dismissed as science fiction and cited as an existential threat. No rigorous population survey tracks how often Americans worry about asteroid strikes specifically, but asteroid-impact scenarios reliably generate outsized media coverage whenever a newly discovered near-Earth object makes a close approach. The result is an availability-driven sense that the risk is either zero or catastrophic, with little middle ground.
Rough estimate: ~1 in 10,000 lifetime feels plausible to many who recall the dinosaur analogy
Source: editorial intuition, not polled
Actual
~100 expected fatalities per year globally (statistical average)
Global population, all ages, statistical expectation over geological timescales
Show derivation
Post-Spaceguard estimates put the annualized expected fatalities from asteroid and comet impacts at roughly 100 per year globally, down from the ~1,000/yr figure Chapman & Morrison used in 1994, because the survey has retired the statistical contribution of most civilization-ending impactors (≥1 km). Annual individual risk: 100 / 8 × 10⁹ ≈ 1.25 × 10⁻⁸. Compounded over 59 remaining adult years: 1 − (1 − 1.25 × 10⁻⁸)⁵⁹ ≈ 7.4 × 10⁻⁷. This is a statistical expectation smoothed over millions of years; in any given century the probability of a fatal impact is dominated by a single low-probability, high-casualty event.
Caveats: The "lifetime probability" of dying from an asteroid impact is a statistical fic…
The "lifetime probability" of dying from an asteroid impact is a statistical fiction in a way that most other entries on this site are not. Almost all the expected fatalities come from a single class of event — a large (≥140 m) impactor striking a populated area or triggering a global catastrophe — that has not occurred in recorded history. The annualized figure of ~100 expected fatalities per year is the quotient of billions of potential casualties divided by millions of years between events. In any given human lifetime, the actual probability is overwhelmingly either zero (no impact occurs) or catastrophically high (one does). The uncertainty band spans more than an order of magnitude because the residual population of undiscovered sub-140 m objects is poorly constrained, and because casualty estimates for ocean impacts (tsunami generation) vary by factors of 10–100 depending on modeling assumptions.
Risks at similar odds
Other risks with roughly the same likelihood — useful for calibration.
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The probability of dying from an asteroid or comet impact is one of the most counterintuitive numbers in risk analysis. Chapman and Morrison’s landmark 1994 paper in Nature estimated roughly 1 in 6,000 over a 50-year lifetime — higher than the odds of dying in a plane crash. That figure, however, predated the Spaceguard Survey, which has since catalogued over 95% of near-Earth asteroids 1 km and larger. None of those has any significant chance of hitting Earth in the next century. The post-survey expected death toll drops to roughly 100 fatalities per year globally, yielding a lifetime individual risk closer to 1 in 1,350,000.
The arithmetic behind these numbers is unusual. Unlike car crashes or lightning, which kill small numbers of people frequently, asteroid fatalities are dominated by extremely rare, extremely high-casualty events. A 1 km impactor striking land could kill hundreds of millions; a 10 km impactor would threaten civilization. When you average those casualties over the millions of years between such events, you get a modest-sounding annual expectation. But in any given century, the realized outcome is almost certainly zero deaths — or a catastrophe. The “average” is real in the actuarial sense and meaningless in the experiential one.
Rumpf et al. (2017) refined the casualty modeling for smaller impactors (50–400 m) and found that wind blast and overpressure shock waves — not the fireball or crater — are the dominant kill mechanisms for land impacts. Tsunamis from ocean impacts add further uncertainty; modelers disagree by an order of magnitude on how efficiently a mid-ocean strike translates into coastal casualties. NASA’s CNEOS Sentry system continuously scans for potential impactors, and the DART mission demonstrated kinetic deflection in 2022, so the risk is not merely observed but actively managed — a distinction no other entry on this site can claim.
The practical takeaway is simple: asteroid impact is a real but extraordinarily rare hazard, comparable in annualized risk to lightning and far below everyday transport dangers. The reason it draws disproportionate attention is not irrationality — an unmitigated large impact would be among the worst disasters in human history — but the mind’s difficulty distinguishing “incredibly unlikely” from “impossible.”
Related tidbits
Lifetime odds of dying from a lightning strike: ~1 in 138,849. From an asteroid impact: roughly 1 in 1,600,000. Lightning is about 12x more likely. Neither justifies worry, but only one gets NASA a budget line.
Claim ledger
Every number below is what each source reported, with the verbatim quote we relied on and how we arrived at our figure. Click any link to verify directly.
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[1] Nature — Impacts on the Earth by asteroids and comets: assessing the hazard
Impacts on the Earth by asteroids and comets: assessing the hazard- Statistic
Individual lifetime risk of ~1 in 6,000 over 50 years (pre-Spaceguard, including civilization-ending impacts)- Excerpt
“"There is a 1-in-10,000 chance that a large (~2-km diameter) asteroid or comet will collide with the Earth during the next century, disrupting the ecosphere and killing a large fraction of the world's population." ”
- Source data from
- 1994-01-06
- Accessed
- 2026-04-12 · archived copy
- Calculation
- Chapman & Morrison 1994 estimated ~1,000 expected fatalities per year globally from all NEO sizes, yielding a 50-year individual risk of roughly 1 in 6,000. This was a pre-Spaceguard estimate that included the full statistical contribution of rare civilization-ending impacts (≥1 km). Subsequent survey work has retired most of that contribution; the revised post-Spaceguard expectation is ~100 fatalities/yr, which reduces the lifetime figure by roughly an order of magnitude.
- Independence
- Chapman & Morrison's framework is the foundational risk assessment; later estimates by Stokes et al. (2003) and Rumpf et al. (2017) use independent impact-physics models and updated NEO population surveys but build on the same probabilistic approach.
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[2] NASA Center for Near Earth Object Studies — Sentry: Earth Impact Monitoring
Sentry: Earth Impact Monitoring- Statistic
No known large NEO has any significant probability of impacting Earth in the next 100 years; 95%+ of 1 km+ NEOs catalogued- Excerpt
“"Sentry is a highly automated collision monitoring system that continually scans the most current asteroid catalog for possibilities of future impact with Earth over the next 100 years." ”
- Source data from
- 2025-12-31
- Accessed
- 2026-04-12 · archived copy
- Calculation
- NASA CNEOS Sentry continuously monitors all catalogued NEOs. As of 2025, approximately 95% of near-Earth asteroids 1 km and larger have been discovered, and none has a significant impact probability in the next century. The residual risk comes almost entirely from undiscovered objects below 140 m. The post-survey annualized fatality expectation of ~100/yr globally (down from ~1,000/yr) reflects this retired risk. Individual annual risk: 100 / 8 × 10⁹ ≈ 1.25 × 10⁻⁸. Over 59 adult years: 1 − (1 − 1.25 × 10⁻⁸)⁵⁹ ≈ 7.4 × 10⁻⁷ ≈ 1 in 1,350,000.
- Independence
- CNEOS Sentry is an operational monitoring system tracking real NEOs with radar and optical astrometry. Its data are independent of the statistical population models used by Chapman & Morrison and Rumpf et al.
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[3] Geophysical Research Letters — Asteroid impact effects and their immediate hazards for human populations
Asteroid impact effects and their immediate hazards for human populations- Statistic
Wind blast and overpressure are the dominant casualty mechanisms for land impacts of 50–400 m asteroids- Excerpt
“"We find that wind blast is the most dangerous impact effect, followed by pressure shock wave and thermal radiation. These three effects account for the vast majority of casualties." ”
- Source data from
- 2017-04-19
- Accessed
- 2026-04-12 · archived copy
- Calculation
- Rumpf et al. 2017 extended casualty modeling to smaller impactor sizes than Chapman & Morrison considered, using high-fidelity impact-physics simulations. Their per-impactor casualty estimates are broadly consistent with earlier work but refine the hazard allocation across effects. The headline lifetime probability we use derives from the post-Spaceguard annualized expectation (~100 fatalities/yr) rather than from Rumpf's per-event figures directly, but Rumpf's work validates the casualty-per-impact assumptions underlying that expectation.
- Independence
- Rumpf et al. use independent impact-physics and population-exposure models distinct from both Chapman & Morrison's analytical approach and CNEOS's orbit-monitoring system.