Impact risk
Sentry is a monitoring system, not an alarm. It lists every object whose orbit has not yet been pinned down tightly enough to rule an impact out — which is a statement about how much we know, far more than about what will happen.
What Sentry is
Sentry continuously scans the catalogue of near-Earth objects for any that could conceivably strike Earth in the next century or so. An object appears on this table not because it is expected to hit us, but because its orbit is not yet known precisely enough for the possibility to be excluded. There are currently 2,205 such objects.
Objects leave the table constantly, and that is the system working. A few more nights of observation usually shrink the orbital uncertainty until every possible impact falls outside it, and the object is removed. Very few entries stay for long.
Highest-rated objects
LiveRanked by the cumulative Palermo scale — not by raw impact probability, which would put a harmless boulder with a badly known orbit above a kilometre-wide object with a well-determined one. 2 objects currently sit above −2, and all remain below 0 — that is, below the background risk from all objects of comparable size.
| Object | Cumulative probability | Years | Palermo (cumulative) | Torino | Diameter |
|---|---|---|---|---|---|
| 29075 (1950 DA)last observed 2025-04-28 UTC | 1 in 2,6531 potential impact | 2880-2880 | -0.93 | — | 1.30 km |
| 101955 Bennu (1999 RQ36)last observed 2020-10-3.80160 UTC | 1 in 1,749157 potential impacts | 2178-2290 | -1.40 | — | 490 m |
| (2008 JL3)last observed 2008-05-09 UTC | 1 in 6,03144 potential impacts | 2027-2122 | -2.38below concern threshold | Torino 0 | 29 m |
| (1979 XB)last observed 1979-12-15 UTC | 1 in 1,174,3764 potential impacts | 2056-2113 | -2.69below concern threshold | Torino 0 | 660 m |
| (2000 SG344)last observed 2000-10-03 UTC | 1 in 365300 potential impacts | 2069-2122 | -2.76below concern threshold | Torino 0 | 37 m |
| (2010 RF12)last observed 2022-08-24 UTC | 1 in 1070 potential impacts | 2095-2122 | -2.96below concern threshold | Torino 0 | 7 m |
| (2007 FT3)last observed 2007-03-21 UTC | 1 in 1,291,26587 potential impacts | 2030-2119 | -3.06below concern threshold | Torino 0 | 341 m |
| (2022 PX1)last observed 2022-08-12 UTC | 1 in 309,5021 potential impact | 2040-2040 | -3.07below concern threshold | Torino 0 | 120 m |
| (2005 QK76)last observed 2005-08-31 UTC | 1 in 14,1756 potential impacts | 2030-2059 | -3.10below concern threshold | Torino 0 | 31 m |
| (2021 GX9)last observed 2021-04-17 UTC | 1 in 12,1622 potential impacts | 2032-2052 | -3.18below concern threshold | Torino 0 | 29 m |
| (2023 DO)last observed 2023-03-26 UTC | 1 in 2,19825 potential impacts | 2057-2092 | -3.55below concern threshold | Torino 0 | 26 m |
| (2019 VB37)last observed 2019-11-03 UTC | 1 in 17,5505 potential impacts | 2049-2067 | -3.59below concern threshold | Torino 0 | 43 m |
| (2013 TP4)last observed 2013-10-12 UTC | 1 in 28,3611 potential impact | 2026-2026 | -3.60below concern threshold | Torino 0 | 11 m |
| (2008 UB7)last observed 2008-10-31 UTC | 1 in 29,54750 potential impacts | 2044-2101 | -3.61below concern threshold | Torino 0 | 58 m |
| (2023 BZ)last observed 2023-02-01 UTC | 1 in 26,1921 potential impact | 2026-2026 | -3.62below concern threshold | Torino 0 | 16 m |
| (2007 DX40)last observed 2007-03-02 UTC | 1 in 12,89293 potential impacts | 2035-2122 | -3.63below concern threshold | Torino 0 | 40 m |
| (2024 JW16)last observed 2024-05-16 UTC | 1 in 431,80312 potential impacts | 2082-2121 | -3.63below concern threshold | Torino 0 | 220 m |
| (2024 TK5)last observed 2024-10-08 UTC | 1 in 2,9881 potential impact | 2028-2028 | -3.63below concern threshold | Torino 0 | 10 m |
| (2016 YM4)last observed 2017-02-02 UTC | 1 in 74,7381 potential impact | 2121-2121 | -3.68below concern threshold | Torino 0 | 110 m |
| (2012 HG2)last observed 2012-05-29 UTC | 1 in 373821 potential impacts | 2052-2126 | -3.70below concern threshold | Torino 0 | 14 m |
| (2000 SB45)last observed 2000-09-29 UTC | 1 in 6,310194 potential impacts | 2067-2118 | -3.71below concern threshold | Torino 0 | 46 m |
| (2026 CQ4)last observed 2026-03-22 UTC | 1 in 19939 potential impacts | 2072-2125 | -3.72below concern threshold | Torino 0 | 10 m |
| (2007 KE4)last observed 2007-05-26 UTC | 1 in 50,9763 potential impacts | 2029-2096 | -3.76below concern threshold | Torino 0 | 31 m |
| (2025 BA1)last observed 2025-01-22 UTC | 1 in 2,82427 potential impacts | 2032-2116 | -3.76below concern threshold | Torino 0 | 10 m |
| (2008 EX5)last observed 2008-04-06 UTC | 1 in 18,79228 potential impacts | 2056-2093 | -3.77below concern threshold | Torino 0 | 59 m |
Reading these numbers
Between −2 and 0 on the Palermo scale: the hazard is smaller than the background risk from comparable objects, and warrants monitoring rather than concern.
An impact probability of “1 in 300,000” is not a forecast that something will happen; it is the width of the remaining uncertainty in an orbit. JPL states plainly that these probabilities “can easily be inaccurate by a factor of a few, and occasionally by a factor of ten or more”.
Objects leavethis table. That is what normally happens: more observations shrink the orbit's uncertainty until the possible impact is ruled out entirely. A disappearance from Sentry is the system working, not data going missing.
JPL's own caveat
JPL states of Sentry impact probabilities: “The probability computation is complex and depends on a number of assumptions that are difficult to verify. For these reasons the stated probability can easily be inaccurate by a factor of a few, and occasionally by a factor of ten or more.” It also notes there is no guarantee any particular API remains available.
That caveat is the reason this page does not round these figures into headlines. A probability that could be wrong by a factor of ten is a useful monitoring signal and a terrible basis for alarm, which is exactly how JPL treats it and exactly how AsteriaStar presents it.
The two scales
Palermo
A logarithmic comparison against the background risk: how much more or less likely this specific object is to cause damage than the general population of objects its size, over the time remaining until the potential impact. Zero means “as likely as the background”. Minus two means a hundred times less likely, and is the threshold the scale itself sets for public concern. Essentially every object ever listed has been well below it.
Torino
A 0–10 integer scale for public communication, combining impact probability with kinetic energy. It is defined only for potential impacts less than a century away. Zero means the collision chance is zero or effectively zero, and that is where almost every object has always sat. Only one object has ever briefly reached level 4, and further observations returned it to zero.
Provenance
Every figure here is JPL's or the Minor Planet Centre's. AsteriaStar computes no impact probability and applies no danger rating of its own: where a hazard is named, it is on a scale the issuing agency defined, quoted as they define it. A close approach is described by its distance and its uncertainty, because that is what the data says. Objects pass within a few lunar distances routinely, and the word for that is “routine”.
Sentry risk table
Live- Status
- Live
- Kind
- Model product
- Provider
- JPL Solar System Dynamics / CNEOS
- Organisation
- NASA Jet Propulsion Laboratory, California Institute of Technology
- Fetched
- 2026-09-17 07:29 UTC
- Provider cadence
- 1 d
- Cached for
- 6 h
- Treated as stale after
- 1 d
- Licence
- Public domain (US Government work), NASA/JPL-Caltech.
Source file: https://ssd-api.jpl.nasa.gov/sentry.api
Sentry impact-risk table from JPL Solar System Dynamics / CNEOS, fetched from https://ssd-api.jpl.nasa.gov/sentry.api. Sentry is re-run when new observations arrive for a listed object; entries persist for months or years and change slowly. Six hours is well inside that, and keeps a page view from becoming a request to a research service.
Impact probabilities are JPL's own, with JPL's own caveat that they can be wrong by a factor of a few and occasionally by ten or more. Diameters are estimated from absolute magnitude assuming an albedo of 0.154 unless a measurement exists. Objects LEAVE this table when further observations eliminate their potential impacts — a disappearance is good news, not missing data. The Torino scale is defined only for potential impacts less than a century away.
Sources & references
The primary and reference sources this topic draws on.
- NASA JPLJet Propulsion Laboratory / Solar System Dynamics
Orbital data, ephemerides, and small-body parameters for planets, asteroids, and comets.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.