Editing Palermo scale (section)

== Asteroids with high ratings ==
{{merge|section=yes|List of objects with non-zero Torino ratings|target=List of near-Earth objects with significant impact hazard ratings|discuss=Talk:List_of_objects_with_non-zero_Torino_ratings#Merge_proposal|date=February 2025}}
In 2002 the near-Earth asteroid {{mpl|(89959) 2002 NT|7}} reached a positive rating of 0.18 on the Palermo scale,<ref name="hohmanntransfer"/> indicating a higher-than-background threat. The value was subsequently lowered after more measurements were taken. {{mp|2002 NT|7}} is no longer considered to pose any risk and was removed from the [[Sentry (monitoring system)|Sentry Risk Table]] on 1 August 2002.<ref name="removed"/>

In September 2002, the highest Palermo rating was that of asteroid [[(29075) 1950 DA]], with a value of 0.17 for a possible collision in the year 2880.<ref name="NEO-1950DA_1"/> By March 2022, the rating had been reduced to −2.0.<ref name="SEIM29075"/><ref>{{cite web |title=Updated Calculations Refine the Impact Probability for (29075) 1950 DA |url=https://cneos.jpl.nasa.gov/news/news208.html |website=Center for NEO Studies (CNEOS) |publisher=JPL (NASA) |access-date=19 August 2022 |ref=Update}}</ref> In May 2024, a study that incorporated observations by the [[astrometry]] space observatory ''[[Gaia (spacecraft)|Gaia]]'' increased the impact risk, consequently, the rating was raised above −1 again.<ref>{{cite journal |first1=Oscar |last1=Fuentes-Muñoz |first2=Davide |last2=Farnocchia |first3=Shantanu P. |last3=Naidu |first4=Ryan S. |last4=Park |title=Asteroid Orbit Determination Using Gaia FPR: Statistical Analysis |journal=[[The Astronomical Journal]] |volume=167 |issue=6 |date=May 31, 2024 |page=290 |doi=10.3847/1538-3881/ad4291 |doi-access=free |bibcode=2024AJ....167..290F }}</ref>

For a brief period in late December 2004, with an [[observation arc]] of 190 days, asteroid {{mpl|99942 Apophis}} (then known only by its [[provisional designation]] {{mp|2004 MN|4}}) held the record for the highest Palermo scale value, with a value of 1.10 for a possible collision in the year 2029.<ref name="mirror"/> The 1.10 value indicated that a collision with this object was considered to be almost 12.6<ref name=Apophis-math>Math: 10<sup>1.10</sup>&nbsp;=&nbsp;12.589</ref> times as likely as a random background event: 1 in 37<ref name="predicting-Apophis"/> instead of 1 in 472. With further observations, the risk of impact during later close approaches was completely eliminated<ref>{{cite news |title=NASA Analysis: Earth Is Safe From Asteroid Apophis for 100-Plus Years |date=March 25, 2021 |work=News |publisher=NASA/JPL |url=https://www.jpl.nasa.gov/news/nasa-analysis-earth-is-safe-from-asteroid-apophis-for-100-plus-years |access-date=January 2, 2025 |url-status=live |archive-url=https://web.archive.org/web/20241212054436/https://www.jpl.nasa.gov/news/nasa-analysis-earth-is-safe-from-asteroid-apophis-for-100-plus-years/ |archive-date=December 12, 2024 }}</ref> and Apophis was removed from the Sentry Risk Table in February 2021.<ref name="removed"/>

{{As of|2025|4|27}}, on NASA's Sentry Risk Table,<ref name="cneos-sentry">{{cite web |title=Sentry: Earth Impact Monitoring - Impact Risk Data |url=https://cneos.jpl.nasa.gov/sentry/ |publisher=[[Jet Propulsion Laboratory]] |access-date=2025-03-10 |quote=Use unconstrained settings, sort by Palermo Scale (cum.) |archive-date=2025-01-31 |archive-url=https://web.archive.org/web/20250131135418/https://cneos.jpl.nasa.gov/sentry/ |url-status=live}}</ref> two asteroids have a cumulative Palermo scale value above −2: [[(29075) 1950 DA]] (−0.92) and [[101955 Bennu]] (−1.40). Five have cumulative Palermo scale values between −2 and −3: {{mpl|2025 FA|22}} (−2.34), {{mpl|1979 XB|}} (−2.70), {{mpl|2000 SG|344}} (−2.77), {{mpl|2008 JL|3}} (−2.86) and {{mpl|2010 RF|12}} (−2.97). Of the 29 that have a cumulative Palermo scale value between −3 and −4, three were discovered in 2024 and one in 2025: {{mpl|2024 BY|15}} (−3.30), {{mpl|2025 EL|12}} (−3.32), {{mpl|2024 JW|16}} (−3.63) and {{mpl|2024 TK|5}} (−3.76).<!-- This data should be checked by changing the default impact probability filter to "Any impact probability"-->

{{As of|2025|4|27}}, on the Risk List maintained by the [[Near-Earth Object Coordination Centre]] of the [[European Space Agency]] (ESA),<ref>{{Cite web |title=Risk List |url=https://neo.ssa.esa.int/risk-list |access-date=2025-03-03 |publisher=[[European Space Agency|ESA]] [[Near-Earth Object Coordination Centre|NEOCC]] }}</ref> one asteroid has a cumulative Palermo scale value above −2: 101955 Bennu (−1.41). Seven have cumulative Palermo scale values between −2 and −3: 1950 DA (−2.13)<!-- According to email information from NEOCC, the big difference from the CNEOS figure is because CNEOS did an update including Gaia observations, while NEOCC has yet to update its software for that-->, {{mpl|2025 FA|22}} (−2.61), {{mpl|2023 VD|3}} (−2.62), 1979 XB (−2.70), {{mp|2008 JL|3}} (−2.73), {{mp|2000 SG|344}} (−2.77) and {{mp|2017 AE|21}} (−2.82). Of the 25 that have a cumulative Palermo scale value between −3 and −4, two were discovered in 2024 and two in 2025: {{mpl|2025 EL|12}} (−3.33), {{mpl|2024 RF|10}} (−3.51), {{mp|2024 JW|16}} (−3.53) and {{mpl|2025 BA|1}} (−3.82).<!-- Sort by "PS cum". Note that Bennu & 1950 DA are listed separately under "Special Risk List". For those, no cumulative Palermo rating is given, for Bennu which has multiple possible impacts, it has to be calculated f.e. in an Excel table-->

{| class="wikitable" style="text-align:center; font-size: 0.9em;"
|+Historic cumulative Palermo ratings above &minus;1 in NASA's Sentry Risk Table
! rowspan=2 | Asteroid
! colspan=3 | Peak hazard
! colspan=3 | Hazard {{As of|2025|4|10|lc=y}}<ref name="cneos-sentry"/><ref name="removed"/>
|-
! Palermo rating
! Risk relative to<br>background risk
! Torino rating
! Palermo rating
! Risk relative to<br>background risk
! Torino rating
|-
| [[99942 Apophis]] || 1.10 || 12.6× greater (1260%) || 4 ||colspan="3"| ''removed from list on 21 February 2021''
|-
| {{mpl|(89959) 2002 NT|7}} || 0.18 || 1.51× greater (151%) || 1 ||colspan="3"| ''removed from list on 1 August 2002''
|-
| [[(29075) 1950 DA]] || 0.17 || 1.48× greater (148%) || - || −0.92 || 8.32× less (12.0%) || -
|--bgcolor=#c2c2c2
| background risk  || 0 || equal (100%) || - || 0 || equal (100%) || -
|-
| {{mpl|2024 YR|4}} || −0.18 || 1.51× less (66.1%) || 3  || −4.25 || 17,783× less (0.0056%) || 0
|-
| {{mpl|(144898) 2004 VD|17}} || −0.25 || 1.78× less (56.2%) || 2 ||colspan="3"| ''removed from list on 14 February 2008''
|-
| [[(410777) 2009 FD]] || −0.44 || 2.75× less (36.3%) || - ||colspan="3"| ''removed from list on 19 November 2020''
|-
| {{mpl|2022 AE|1}} || −0.66 || 4.57× less (21.9%) || 1 ||colspan="3"| ''removed from list on 20 January 2022''
|-
| {{mpl|2023 GQ|2}} || −0.70 || 5.01× less (20.0%) || 1 ||colspan="3"| ''removed from list on 1 May 2023''
|-
| {{mpl|2013 TV|135}} || −0.73 || 5.37× less (18.6%)  || 1||colspan="3"| ''removed from list on 8 November 2013''
|-
| {{mpl|(367789) 2011 AG|5}} || −1.00 || 10× less (10%) || 1 ||colspan="3"| ''removed from list on 21 December 2012''
|}