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Sentry (monitoring system)
Sentry is an automated impact prediction system started in 2002 and operated by the Center for Near Earth Object Studies (CNEOS) at NASA's Jet Propulsion Laboratory. It continually monitors the most up-to-date asteroid catalog for possibilities of future impact with Earth over the next 100+ years. Whenever a potential impact is detected, it will be analyzed and the results immediately published by CNEOS. However, alerts do not imply certainty about future impacts, as the small amounts of optical data that can trigger an alert are not enough to conclusively identify an impact years in the future. In contrast, eliminating an entry on the risk page is a negative prediction (a prediction of where it will not be).
Scientists warn against worrying about the possibility of impact with an object based on only a few weeks of optical data that show a possible Earth encounter years from now. Sometimes, it cannot even be said for certain what side of the Sun such an object will be at the time of the listed virtual impactor date. For example, even though 2005 ED224 had a 1-in-500,000 chance of impacting Earth on 11 March 2023, its most likely position at that date was farther away than the Sun. Most objects in the Sentry Risk Table have an observation arc of less than 14 days, making their positions highly uncertain, and have not been observed for years.
There are 1888 near-Earth asteroids listed in the risk table and 41,848 virtual impact dates, so for each asteroid in the risk table, there is an average of about 22 virtual impact dates. Only about 21 objects in the table are large enough, with a diameter greater than about 140 meters, to be considered potentially hazardous objects. The average size of an object on the default page of Sentry is 120 meters, with an average impact probability of about 1 in 500. More eccentric orbits (such as 2015 RD36) that extend to nearly the orbit of Jupiter can make atmospheric entry at velocities of ~40 km/s (25 mi/s).
The Impact Risk page lists a number of lost minor planets that are, for all practical purposes, permanent residents of the risk page; their removal may depend upon a serendipitous rediscovery. Lost asteroid 1979 XB has been on the list since the list's inception. 2007 FT3 and 2014 MV67 with their very short 1-day observation arcs have missed virtual impactor dates as they were likely quite distant from the Earth at the time. 1997 XR2 was serendipitously rediscovered in 2006 after being lost for more than 8 years. 2004 BX159 was determined to be a harmless main belt asteroid in 2014. Some objects on the Sentry Risk Table, such as 2000 SG344, might even be artificial.
2010 RF12 is the asteroid with greatest probability (10%) of impacting Earth, but is only ~7 meters in diameter. The only numbered objects with observation arcs of several years are (29075) 1950 DA and 101955 Bennu. Notable asteroids removed from Sentry include (most recently removed listed first): 99942 Apophis, (410777) 2009 FD, 2006 QV89, 2017 XO2, 1994 WR12, 2007 VK184, 2013 BP73, 2008 CK70, 2013 TV135, 2011 BT15, 367943 Duende, and 2011 AG5.
As of February 2025[update], of the 191 asteroids with better than a 1-in-10,000 chance of impacting Earth only (29075) 1950 DA and 101955 Bennu are larger than 50 meters in diameter.
As of March 2025[update], the soonest virtual impactor of an asteroid larger than 50 meters in diameter with a better than 1:1-million chance of impact is 2022 PX1 on 11 August 2040 with a 1:310000 chance of impact. It is estimated to be 120-meters in diameter, has a short observation arc of 7-days, and is expected to be approximately 1.75 AU (262 million km) from Earth on 11 August 2040. The impact scenario is outside the 3-sigma uncertainty region of ± 242 million km.
The asteroid with the greatest chance of impacting Earth in 2025 is 2009 VA (6-meters in diameter) with less than a 1-day observation arc. It has a 1:48,000 chance of impact on 06 November 2023, but is expected to be around 0.3 AU (45 million km) from Earth on that date with uncertainty region of ± 900 million km.
Hub AI
Sentry (monitoring system) AI simulator
(@Sentry (monitoring system)_simulator)
Sentry (monitoring system)
Sentry is an automated impact prediction system started in 2002 and operated by the Center for Near Earth Object Studies (CNEOS) at NASA's Jet Propulsion Laboratory. It continually monitors the most up-to-date asteroid catalog for possibilities of future impact with Earth over the next 100+ years. Whenever a potential impact is detected, it will be analyzed and the results immediately published by CNEOS. However, alerts do not imply certainty about future impacts, as the small amounts of optical data that can trigger an alert are not enough to conclusively identify an impact years in the future. In contrast, eliminating an entry on the risk page is a negative prediction (a prediction of where it will not be).
Scientists warn against worrying about the possibility of impact with an object based on only a few weeks of optical data that show a possible Earth encounter years from now. Sometimes, it cannot even be said for certain what side of the Sun such an object will be at the time of the listed virtual impactor date. For example, even though 2005 ED224 had a 1-in-500,000 chance of impacting Earth on 11 March 2023, its most likely position at that date was farther away than the Sun. Most objects in the Sentry Risk Table have an observation arc of less than 14 days, making their positions highly uncertain, and have not been observed for years.
There are 1888 near-Earth asteroids listed in the risk table and 41,848 virtual impact dates, so for each asteroid in the risk table, there is an average of about 22 virtual impact dates. Only about 21 objects in the table are large enough, with a diameter greater than about 140 meters, to be considered potentially hazardous objects. The average size of an object on the default page of Sentry is 120 meters, with an average impact probability of about 1 in 500. More eccentric orbits (such as 2015 RD36) that extend to nearly the orbit of Jupiter can make atmospheric entry at velocities of ~40 km/s (25 mi/s).
The Impact Risk page lists a number of lost minor planets that are, for all practical purposes, permanent residents of the risk page; their removal may depend upon a serendipitous rediscovery. Lost asteroid 1979 XB has been on the list since the list's inception. 2007 FT3 and 2014 MV67 with their very short 1-day observation arcs have missed virtual impactor dates as they were likely quite distant from the Earth at the time. 1997 XR2 was serendipitously rediscovered in 2006 after being lost for more than 8 years. 2004 BX159 was determined to be a harmless main belt asteroid in 2014. Some objects on the Sentry Risk Table, such as 2000 SG344, might even be artificial.
2010 RF12 is the asteroid with greatest probability (10%) of impacting Earth, but is only ~7 meters in diameter. The only numbered objects with observation arcs of several years are (29075) 1950 DA and 101955 Bennu. Notable asteroids removed from Sentry include (most recently removed listed first): 99942 Apophis, (410777) 2009 FD, 2006 QV89, 2017 XO2, 1994 WR12, 2007 VK184, 2013 BP73, 2008 CK70, 2013 TV135, 2011 BT15, 367943 Duende, and 2011 AG5.
As of February 2025[update], of the 191 asteroids with better than a 1-in-10,000 chance of impacting Earth only (29075) 1950 DA and 101955 Bennu are larger than 50 meters in diameter.
As of March 2025[update], the soonest virtual impactor of an asteroid larger than 50 meters in diameter with a better than 1:1-million chance of impact is 2022 PX1 on 11 August 2040 with a 1:310000 chance of impact. It is estimated to be 120-meters in diameter, has a short observation arc of 7-days, and is expected to be approximately 1.75 AU (262 million km) from Earth on 11 August 2040. The impact scenario is outside the 3-sigma uncertainty region of ± 242 million km.
The asteroid with the greatest chance of impacting Earth in 2025 is 2009 VA (6-meters in diameter) with less than a 1-day observation arc. It has a 1:48,000 chance of impact on 06 November 2023, but is expected to be around 0.3 AU (45 million km) from Earth on that date with uncertainty region of ± 900 million km.