How many near-Earth asteroids are known, and which ones come close next year?

Steps

1. Four data requests, one at a time and cached: CNEOS nea_vs_time.json and size_bin.json, an SBDB Query API call for every near-Earth asteroid (42,662 rows; kind a, group neo, full precision) and a Close-Approach Data API call (dist-max 0.05 au, body Earth, 2026-10-09 to 2027-10-09, 159 rows). Yearly discoveries are differences of CNEOS's series at December 31. Every yearly total, 140 m count and 1 km count was compared with an independent count from the SBDB rows (the year in each asteroid's provisional designation; H of 22.0 or less and 17.75 or less): yearly totals within 5%, the cumulative total within 1% (CNEOS 42,693, SBDB designations 42,314 since 1996 against CNEOS 42,353). The size formula reproduces 246 cells of JPL's published size table within its rounding.
2. A near-Earth asteroid is an asteroid whose orbit brings it within 1.3 au of the Sun (SBDB neo flag). Discovery counts come from CNEOS's cumulative series (known NEAs by discovery date, split by size: all, about 140 m and larger, about 1 km and larger) and are the difference between consecutive year ends. CNEOS sizes are from absolute magnitude H or a measured diameter. Close approaches are JPL's computed approaches to Earth within 0.05 au (about 19.5 lunar distances) in the window; the date and time are TDB, about 69 seconds ahead of UTC. Where an asteroid's diameter is not measured, it is estimated from H with the CNEOS formula d = 10^(3.1236 - 0.5 log10(albedo) - 0.2 H) km, shown as a range for a bright surface (albedo 0.25) to a dark one (albedo 0.05), with the value at albedo 0.15 as the central estimate.
3. The sample for the System overlay (data/space/neo_orbits.json) is 300 asteroids: the 159 objects above, 18 well-known ones (Eros, Apophis, Bennu, Ryugu, Itokawa, Didymos and others, each checked by number and name) and the 123 brightest named near-Earth asteroids.

31 yearly rows (1996 to 2026) from 42,693 known asteroids; 159 predicted approaches. Unit: Number of near-Earth asteroids; distance in lunar distances (1 LD = 384,400 km); size in metres. Every derived figure on this page (changes, indexes, averages, counts) is computed from the published rows, and the table under each chart says how.

Checks

• Every year's total, 140 m count and 1 km count from CNEOS was compared with an independent count from 42,662 SBDB rows (the year in each provisional designation; H at most 22.0 and 17.75). The script stops if a yearly total differs by more than 5%, a 140 m count by more than 8%, or a 1 km count by more than 4. CNEOS counts 42,693, SBDB 42,662; the 31 difference (0.07%) is the gap between the two sources; its cause is not known.
• The CNEOS size chart (size_bin.json) adds up to the cumulative total (42,693).
• The size formula reproduces all 246 cells of JPL's published size table within its rounding. Where JPL lists a measured diameter, it falls inside the range the formula gives.
• Potentially hazardous asteroids: SBDB flags 2,550; applying the CNEOS definition to the rows gives 2,534. The 16 difference comes from rounding of H and measured sizes.
• The script stops if the CNEOS series, the SBDB or close-approach field lists, or JPL's lunar-distance or hazardous-asteroid definitions change, and it makes each JPL request once, one at a time.

Caveats

• CNEOS's size classes mix measured diameters and sizes inferred from H with an assumed albedo, so a count by size is an estimate: an asteroid that is darker than assumed is bigger than its class says. Discoveries per year follow the survey, not the sky: the rise since 2013 is mostly new survey capacity. The close-approach list contains only asteroids known today, and new discoveries add approaches that are not yet listed (small asteroids are often found days before or after they pass). An approach date and distance are computed from the orbit known now and move as more observations arrive; 63 of the 159 have a 3-sigma distance range wider than half the nominal distance. 'Close' here means 0.05 au or less (about 19.5 lunar distances); none of these has a predicted impact. Sizes in the approach list are estimates from H unless marked measured (2 are measured).
• A lunar distance is the average Earth-Moon distance, 384,400 km. Times are TDB, about 69 seconds ahead of UTC. The approach list starts at 00:00 on Oct 9, 2026, so anything on Oct 8 is not shown.
• Discovery counts follow the survey, not the sky: the numbers grew because telescopes and software improved, not because there are more asteroids.

Releases and revisions

• CNEOS discovery statistics dated 2026-Oct-08; SBDB query of 2026-10-08 (42,662 near-Earth asteroids); close approaches computed by JPL on 2026-10-08 for 2026-10-09 to 2027-10-09
• CNEOS updates the statistics as asteroids are found and the close-approach list daily. Next: re-run space_near_earth_asteroids.py to refresh; JPL's fair use policy asks that requests be cached and reused.