Space · Planetary Defense

Known NEAs, Roughly 1 km+

The hunt for the asteroids that could end civilisation is more than 90% finished.

• 299 → 881 known roughly 1 km+ NEAs
• Only 16 added from 2020 to 2025
• >90% of 1 km+ NEOs found, CNEOS says
• H ≤ 17.75; 14% albedo, not measured sizes

One kilometre is roughly the size at which an asteroid impact stops being a regional disaster and becomes a global one, which is what makes this particular count worth keeping. Known near-Earth asteroids of roughly that size and larger rose from 299 at the end of 1999 to 772 by the end of 2010, as dedicated sky surveys turned the search from opportunistic to systematic. Then the curve flattened, reaching 881 by the end of 2025 with only 16 of those added in the last five years. The flattening is the achievement rather than a failure: CNEOS reports that over 90% of near-Earth objects larger than one kilometre have already been discovered, and the search has moved on to a harder target, 90% of everything larger than 140 metres. This is an exponential that ended because it ran out of things to find.

Two things sit underneath the numbers. Sizes are inferred rather than measured: CNEOS bins objects with absolute magnitude H ≤ 17.75 as roughly 1 km and larger, assuming a mean albedo of 14%. And each point is a year-end count of what is known now, grouped by discovery date in the Minor Planet Center catalogue, so later orbit or magnitude revisions can still edit the early history slightly. The daily table has read 883 at every monthly sample since February 2026, a mid-year figure the chart does not plot.

Source: JPL CNEOS, derived from the Minor Planet Center catalogue

Download the data: large_nea_discoveries.csv · large_nea_discoveries.json

All curves · The chart is drawn in your browser and needs JavaScript. Every number it plots is in the table above.