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Potentially hazardous object

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From Wikipedia, the free encyclopedia

Hazardous near-Earth asteroid or comet

The asteroidToutatis is listed as a potentially hazardousnear-Earth asteroid, yet poses no immediate threat to Earth. (Radar image taken byGDSCC in 1996.)

Apotentially hazardous object (PHO) is anear-Earth object – either anasteroid or acomet – with anorbit that can make close approaches to theEarth and which is large enough to cause significant regional damage in theevent of impact.^[1] They are conventionally defined as having aminimum orbit intersection distance with Earth of less than 0.05astronomical units (19.5lunar distances) and anabsolute magnitude of 22 or brighter, the latter of which roughly corresponds to a size larger than 140 meters.^[2] More than 99% of the known potentially hazardous objects are no impact threat over the next 100 years.^[3] As of February 2025^[update], just 21 of the known potentially hazardous objects listed on theSentry Risk Table could not be excluded as potential threats over the next hundred years.^[4] Over hundreds if not thousands of years though, the orbits of some "potentially hazardous" asteroids can evolve to live up to their namesake.

Most of these objects arepotentially hazardous asteroids (PHAs), and a few arecomets. As of November 2022^[update] there are 2,304 known PHAs (about 8% of the total near-Earth population), of which 153 are estimated to be larger than one kilometer in diameter(see list oflargest PHAs below).^[5]^[6]^[a] Most of the discovered PHAs areApollo asteroids (1,965) and fewer belong to the group ofAten asteroids (185).^[7]^[8]

A potentially hazardous object can be known not to be a threat to Earth for the next 100 years or more, if its orbit is reasonably well determined. Potentially hazardous asteroids with some threat of impacting Earth in the next 100 years are listed on the Sentry Risk Table. As of September 2022^[update], only 17 potentially hazardous asteroids are listed on the Sentry Risk Table.^[4] Most potentially hazardous asteroids are ruled out as hazardous to at least several hundreds of years when their competing best orbit models are sufficiently constrained, but recent discoveries whose orbital constraints are little-known have divergent or incomplete mechanical models until observation yields further data. After severalastronomical surveys, the number of known PHAs has increased tenfold since the end of the 1990s(seebar charts below).^[5] TheMinor Planet Center's websiteList of the Potentially Hazardous Asteroids also publishes detailed information for these objects.^[9]

In May 2021, NASA astronomers reported that 5 to 10 years of preparation may be needed to avoid apotential impactor, as most recently based on a simulated exercise conducted by the 2021 Planetary Defense Conference.^[10]^[11]^[12]

Overview

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Plot of orbits of known potentially hazardous asteroids, with sizes over 140 metres (460 ft) and that pass within 7.6 million kilometres (4.7×10^⁶ mi) of Earth's orbit.Epoch as of early 2013.

An object is considered a PHO if itsminimum orbit intersection distance (MOID) with respect to Earth is less than 0.05 AU (7,500,000 km; 4,600,000 mi) – approximately 19.5 lunar distances – and itsabsolute magnitude is brighter than 22, approximately corresponding to a diameter above 140 meters (460 ft).^[1]^[2] This is big enough to cause regional devastation to human settlements unprecedented in human history in the case of a land impact, or a majortsunami in the case of anocean impact. Such impact events occur on average around once per 10,000 years.NEOWISE data estimates that there are 4,700 ± 1,500 potentially hazardous asteroids with a diameter greater than 100 meters.^[13]

Levels of hazard

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Main articles:Torino scale andPalermo scale

The two main scales used to categorize the impact hazards of asteroids are the Palermo scale and the Torino scale.

Potentially hazardous comet

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Apotentially hazardous comet (PHC) is a short-period comet which currently has an Earth-MOID less than 0.05 AU. Known PHCs include:109P/Swift-Tuttle,55P/Tempel–Tuttle,15P/Finlay,289P/Blanpain,255P/Levy,206P/Barnard–Boattini,21P/Giacobini–Zinner, and73P/Schwassmann–Wachmann.Halley's Comet fit the criteria before AD 837, when it passed the earth at a distance of 0.033 AU. It now has an MOID of 0.075 AU.

Numbers

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DetectedNEAs by variousprojects. The broader class of NEAs includes all PHAs as a subset.^[5]
  LINEAR
  NEAT
  Spacewatch
  LONEOS
  CSS   Pan-STARRS
  NEOWISE
  ATLAS
  Others

In 2012NASA estimated 20 to 30 percent of these objects have been found.^[13] During an asteroid's close approaches to another planet it will be subject to gravitationalperturbation, modifying its orbit, and potentially changing a previously non-threatening asteroid into a PHA or vice versa. This is a reflection of the dynamic character of the Solar System.

Severalastronomical survey projects such asLincoln Near-Earth Asteroid Research,Catalina Sky Survey andPan-STARRS continue to search for more PHOs. Each one found is studied by various means, including optical,radar, andinfrared to determine its characteristics, such as size, composition, rotation state, and to more accurately determine its orbit. Both professional andamateur astronomers participate in such observation and tracking.

Size

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Asteroids larger than approximately 35 meters across can pose a threat to a town or city.^[14] However the diameter of most small asteroids is not well determined, as it is usually only estimated based on their brightness and distance, rather than directly measured, e.g. from radar observations. For this reasonNASA and theJet Propulsion Laboratory use the more practical measure ofabsolute magnitude (H). Any asteroid with an absolute magnitude of 22.0 or brighter is assumed to be of the required size.^[2]

Only a coarse estimation of size can be found from the object's magnitude because an assumption must be made for itsalbedo which is also not usually known for certain. The NASAnear-Earth object program uses an assumedalbedo of 0.14 for this purpose. In May 2016, the asteroid size estimates arising from theWide-field Infrared Survey Explorer andNEOWISE missions have been questioned.^[15]^[16]^[17] Although the early original criticism had not undergone peer review,^[18] a more recent peer-reviewed study was subsequently published.^[19]^[20]

Largest PHAs

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With amean diameter of approximately 7 kilometers, Apollo asteroid(53319) 1999 JM8 is likely the largest known potentially hazardous object, despite its fainterabsolute magnitude of 15.2, compared to other listed objects in the table below(note: calculated mean-diameters in table are inferred from the object's brightness and its (assumed) albedo. They are only an approximation.).

Brightest Potentially Hazardous Asteroids^[9]
Designation	Discovery			(H) (mag)	D (km)	Orbital description							Remarks	References
Designation	Year	Place	Discoverer	(H) (mag)	D (km)	Class	a (AU)	e	i (°)	q (AU)	Q (AU)	MOID (AU)	Remarks	References
(4953) 1990 MU	1990	413	R. H. McNaught	14.1	3	APO	1.621	0.658	24.4	0.555	2.687	0.02640	—	MPC · JPL · catalog
3122 Florence	1981	413	S. J. Bus	14.1	5	AMO	1.769	0.423	22.2	1.020	2.518	0.04430	—	MPC · JPL · catalog
(16960) 1998 QS52	1998	704	LINEAR	14.3	4	APO	2.203	0.858	17.5	0.313	4.093	0.01443	—	MPC · JPL · catalog
4183 Cuno	1959	074	C. Hoffmeister	14.4	4	APO	1.982	0.634	6.7	0.725	3.240	0.02825	—	MPC · JPL · catalog
3200 Phaethon	1983	500	IRAS	14.6	5.8	APO	1.271	0.890	22.3	0.140	2.402	0.01945	—	MPC · JPL · catalog
(242450) 2004 QY2	2004	E12	Siding Spring Survey	14.7	3	APO	1.084	0.477	37.0	0.567	1.601	0.04686	—	MPC · JPL · catalog
(89830) 2002 CE	2002	704	LINEAR	14.9	3.1	AMO	2.077	0.507	43.7	1.023	3.131	0.02767	—	MPC · JPL · catalog
(137427) 1999 TF211	1999	704	LINEAR	15.1	2.9	APO	2.448	0.610	39.2	0.955	3.942	0.01787	—	MPC · JPL · catalog
(111253) 2001 XU10	2001	704	LINEAR	15.2	3	APO	1.754	0.439	42.0	0.983	2.524	0.02934	—	MPC · JPL · catalog
(53319) 1999 JM8	1999	704	LINEAR	15.2	7	APO	2.726	0.641	13.8	0.978	4.474	0.02346	Likely largest PHO	MPC · JPL · catalog
1981 Midas	1973	675	C. T. Kowal	15.2	2	APO	1.776	0.650	39.8	0.621	2.931	0.00449	—	MPC · JPL · catalog
2201 Oljato	1947	690	H. L. Giclas	15.25	2.1	APO	2.175	0.713	2.5	0.624	3.726	0.00305	—	MPC · JPL · catalog
(90075) 2002 VU94	2002	644	NEAT	15.3	2.2	APO	2.134	0.576	8.9	0.904	3.363	0.03010	—	MPC · JPL · catalog
4179 Toutatis	1989	010	C. Pollas	15.30	2.5	APO	2.536	0.629	0.4	0.940	4.132	0.00615	—	MPC · JPL · catalog
(159857) 2004 LJ1	2004	704	LINEAR	15.4	3	APO	2.264	0.593	23.1	0.920	3.607	0.01682	—	MPC · JPL · catalog
(85713) 1998 SS49	1998	704	LINEAR	15.6	3.5	APO	1.924	0.639	10.8	0.694	3.154	0.00234	—	MPC · JPL · catalog
4486 Mithra	1987	071	E. W. Elst V. G. Shkodrov	15.6	2	APO	2.200	0.663	3.0	0.742	3.658	0.04626	—	MPC · JPL · catalog
1620 Geographos	1951	675	A. G. Wilson R. Minkowski	15.60	2.5	APO	1.245	0.335	13.3	0.828	1.663	0.03007	—	MPC · JPL · catalog
(415029) 2011 UL21	2011	703	CSS	15.7	2.5	APO	2.122	0.653	34.9	0.736	3.509	0.01925	—	MPC · JPL · catalog
(242216) 2003 RN10	2003	699	LONEOS	15.7	2.5	AMO	2.231	0.541	39.6	1.024	3.438	0.00956	—	MPC · JPL · catalog
12923 Zephyr	1999	699	LONEOS	15.8	2	APO	1.962	0.492	5.3	0.996	2.927	0.02115	—	MPC · JPL · catalog
(52768) 1998 OR2	1998	566	NEAT	15.8	2	APO	2.380	0.573	5.9	1.017	3.743	0.01573	—	MPC · JPL · catalog

Statistics

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Below is a list of the largest PHAs (based onabsolute magnitude H) discovered in a given year. Historical data of the cumulative number of discovered PHA since 1999 are displayed in the bar charts—one for the total number and the other for objects larger than one kilometer.^[5] PHAs brighter than absolute magnitude 17.75 are likely larger than 1 km in size.

Brightest PHA discoveries of each calendar year since 1989^[9]
Number	Name	Year	(H)	Refs
4179	Toutatis	1989	15.3	MPC · JPL · catalog
4953	1990 MU	1990	14.9	MPC · JPL · catalog
7341	1991 VH	1991	17.0	MPC · JPL · catalog
10115	1992 SK	1992	17.2	MPC · JPL · catalog
39572	1993 DQ₁	1993	16.6	MPC · JPL · catalog
7482	1994 PC₁	1994	16.7	MPC · JPL · catalog
243566	1995 SA	1995	17.4	MPC · JPL · catalog
8566	1996 EN	1996	16.3	MPC · JPL · catalog
35396	1997 XF11	1997	17.0	MPC · JPL · catalog
16960	1998 QS₅₂	1998	14.4	MPC · JPL · catalog
137427	1999 TF₂₁₁	1999	15.3	MPC · JPL · catalog
138095	2000 DK₇₉	2000	16.0	MPC · JPL · catalog
111253	2001 XU₁₀	2001	15.3	MPC · JPL · catalog
89830	2002 CE	2002	15.0	MPC · JPL · catalog
242216	2003 RN₁₀	2003	15.7	MPC · JPL · catalog
242450	2004 QY₂	2004	14.6	MPC · JPL · catalog
308242	2005 GO₂₁	2005	16.3	MPC · JPL · catalog
374851	2006 VV₂	2006	16.7	MPC · JPL · catalog
214869	2007 PA₈	2007	16.5	MPC · JPL · catalog
294739	2008 CM	2008	17.1	MPC · JPL · catalog
523630	2009 OG	2009	16.2	MPC · JPL · catalog
458122	2010 EW₄₅	2010	17.6	MPC · JPL · catalog
415029	2011 UL₂₁	2011	15.9	MPC · JPL · catalog
746849	2012 HJ1	2012	17.9	MPC · JPL · catalog
507716	2013 UP₈	2013	16.4	MPC · JPL · catalog
533671	2014 LJ21	2014	16.1	MPC · JPL · catalog
–	2015 HY116	2015	17.6	MPC · JPL · —
620095	2016 CB194	2016	17.6	MPC · JPL · catalog
–	2017 CH1	2017	17.9	MPC · JPL · —
756316	2018 XV5	2018	17.7	MPC · JPL · catalog
–	2019 RU3	2019	18.1	MPC · JPL · —
–	2020 SL1	2020	17.7	MPC · JPL · —
–	2021 HK12	2021	17.7	MPC · JPL · —
–	2022 AP7	2022	17.3	MPC · JPL · —
–	2023 QF5	2023	18.3	MPC · JPL · —
–	2024 YU4	2024	19.0	MPC · JPL · —

100

150

200

2000

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

2022

2024

Cumulative number of discovered potentially hazardous asteroids larger than 1 kilometer as of January 1 each year. As of January 2025, there are 154 known PHAs larger than one kilometer.^[5]

500

1,000

1,500

2,000

2,500

3,000

2000

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

2022

2024

Cumulative number of all discovered PHAs as of January 1 of each year. As of January 2025, there are 2473 PHAs.^[5]

Gallery

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Radar image of the 350-meter PHO(308635) 2005 YU55

Notes

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^An object's calculated mean-diameter is only a rough estimate. It is inferred from the object's varying brightness—observed and measured at various times—and the assumed, yet often unknown reflectivity of its surface. NASA'sAsteroid Size Estimator is a tool for a genericabsolute magnitude-to-diameter conversion for an assumedgeometric albedo.

References

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^^a ^bTask Force on potentially hazardous Near Earth Objects (September 2000)."Report of the Task Force on potentially hazardous Near Earth Objects"(PDF). Archived fromthe original(PDF) on 10 December 2016. Retrieved22 January 2018.{{cite journal}}:Cite journal requires|journal= (help)
^^a ^b ^c"NEO Basics – Potentially Hazardous Asteroids (PHAs)". CNEOS NASA/JPL. Retrieved16 January 2020.
^(17Sentry "risk-listed" PHAs /2289 known PHAs) ≈ 0.74%
^^a ^b"Sentry Risk Table". Retrieved2022-09-29. (Click "Use Unconstrained Settings" and select "H<=22" for list of PHAs)
^^a ^b ^c ^d ^e ^f"Discovery Statistics – Cumulative Totals". CNEOS NASA/JPL. 7 January 2020. Retrieved16 January 2020.
^"Unusual Minor Planets – Overview". Minor Planet Center. Retrieved16 January 2020.
^"JPL Small-Body Database Search Engine: PHAs and orbital class (APO)". JPL Solar System Dynamics. Retrieved16 January 2020.
^"JPL Small-Body Database Search Engine: PHAs and orbital class (ATE)". JPL Solar System Dynamics. Retrieved16 January 2020.
^^a ^b ^c"List of the Potentially Hazardous Asteroids (PHAs)". Minor Planet Center. Retrieved16 January 2018.
^McFall-Johnsen, Morgan; Woodward, Aylin (12 May 2021)."A NASA simulation revealed that 6 months' warning isn't enough to stop an asteroid from hitting Earth. We'd need 5 to 10 years".Business Insider. Retrieved14 May 2021.
^Bartels, Meghan (1 May 2021)."How did you spend your week? NASA pretended to crash an asteroid into Earth".Space.com. Retrieved14 May 2021.
^Chodas, Paul; Khudikyan, Shakeh; Chamberlin, Alan (30 April 2021)."Planetary Defense Conference Exercise – 2021 Planetary Defense Conference (virtually) in Vienna, Austria, April 26–April 30, 2021".NASA. Retrieved14 May 2021.
^^a ^b"NASA news – NASA Survey Counts Potentially Hazardous Asteroids". NASA/JPL. 16 May 2012. Retrieved22 January 2018.
^Will Ferguson (22 January 2013)."Asteroid Hunter Gives an Update on the Threat of Near-Earth Objects".Scientific American. Retrieved2013-01-23.
^Chang, Kenneth (23 May 2016)."How Big Are Those Killer Asteroids? A Critic Says NASA Doesn't Know".The New York Times. Retrieved24 May 2016.
^Myhrvold, Nathan (23 May 2016). "Asteroid thermal modeling in the presence of reflected sunlight with an application to WISE/NEOWISE observational data".arXiv:1605.06490v2 [astro-ph.EP].
^Billings, Lee (27 May 2016)."For Asteroid-Hunting Astronomers, Nathan Myhrvold Says the Sky Is Falling".Scientific American. Retrieved28 May 2016.
^NASA Administrator (25 May 2016)."NASA Response to Recent Paper on NEOWISE Asteroid Size Results".NASA. Retrieved29 May 2016.
^Myhrvold, Nathan (2018)."An empirical examination of WISE/NEOWISE asteroid analysis and results".Icarus.314:64–97.Bibcode:2018Icar..314...64M.doi:10.1016/j.icarus.2018.05.004.
^Chang, Kenneth (14 June 2018)."Asteroids and Adversaries: Challenging What NASA Knows About Space Rocks – Two years ago, NASA dismissed and mocked an amateur's criticisms of its asteroids database. Now Nathan Myhrvold is back, and his papers have passed peer review".The New York Times. Retrieved14 June 2018.

External links

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Sentry: Earth Impact Monitoring (current) (NASA NEO Program)
Very Close Approaches (<0.01 AU) of PHAs to Earth 1900-2200
TECA Table of Asteroids Next Closest Approaches to the Earth,Sormano Astronomical Observatory
MBPL – Minor Body Priority List (PHA Asteroids),Sormano Astronomical Observatory
Responding to the Threat of Potentially-Hazardous Near Earth Objects (PDF)
Risk of comet hitting Earth is greater than previously thought, say researchers,The Guardian, 22 December 2015
Conversion of Absolute Magnitude to Diameter,Minor Planet Center

Minor Planet Center

[edit]

List of the Potentially Hazardous Asteroids (PHAs)
Asteroid Hazards, Part 2:The Challenge of Detection onYouTube(min. 7:14)
Asteroid Hazards, Part 3:Finding the Path onYouTube(min. 5:38)

Natural disasters –list by death toll

Geological

Mass wasting	Landslide Avalanche Mudflow Debris flow
Earthquake (List)	Seismic hazard Seismic risk Soil liquefaction
Volcano eruption	Pyroclastic flow Lahar Volcanic ash
Natural erosion	Sinkhole

Hydrological

Flood (List)	Coastal flood Flash flood Storm surge
Other	Tsunami Megatsunami Limnic eruption

Meteorological

Temperature	Blizzard Cold wave Ice storm Heat wave
Drought	Megadrought
Cyclonic storms	Bomb cyclone Thunderstorm (Hail) Tornado (Tornado outbreak) Tropical cyclone
Other	Derecho Wildfire Firestorm ARkStorm

Astronomical

Small Solar System bodies

Minor planets

Designation Groups List Moon Meanings of names
Asteroid	Active Aten asteroid Asteroid belt Family Jupiter trojan Near-Earth Spectral types
Distant minor planet	Centaur Neptune trojan Damocloid Trans-Neptunian object Detached Kuiper belt Oort cloud Scattered disc

Comets

Other

Solar System

The Sun, the planets, their moons, and several trans-Neptunian objects

Planets, dwarfs, minors	Terrestrials Mercury Venus Earth Mars Giants Gas Jupiter Saturn Ice Uranus Neptune Dwarfs Ceres Orcus Pluto Haumea Quaoar Makemake Gonggong Eris Sedna Large Minor Planets Salacia Varuna Ixion List
Moons	Earth Moon Claimed Mars Phobos Deimos Jupiter Ganymede Callisto Io Europa all 97 Saturn Titan Rhea Iapetus Dione Tethys Enceladus Mimas Hyperion Phoebe all 274 Uranus Titania Oberon Umbriel Ariel Miranda all 29 Neptune Triton Proteus Nereid all 16 Pluto Charon Nix Hydra Kerberos Styx Orcus Vanth Haumea Hiʻiaka Namaka Quaoar Weywot Makemake S/2015 (136472) 1 Gonggong Xiangliu Eris Dysnomia
Exploration (outline)	Colonization Discovery astronomy historical models timeline Space probes timeline list Human spaceflight space stations list programs Mercury Venus Moon mining Mars Ceres Asteroids mining Comets Jupiter Saturn Uranus Neptune Pluto Deep space
Hypothetical objects	Bagby's moon Chiron Coatlicue Counter-Earth Chrysalis Fifth Giant Hyperion Lilith Mercury's moon Neith Nemesis Nibiru Petit's moon Phaeton Planet Nine Effects Planet Ten Planet V Planet X Subsatellites Synestia Theia Themis Tyche Vulcan Vulcanoids Waltemath's moons
Lists	Comets Possible dwarf planets Gravitationally rounded objects Minor planets Natural satellites Solar System models Solar System objects by size by discovery date Interstellar and circumstellar molecules

Rings	Planetary Jovian Saturnian (Rhean?) Uranian Neptunian Minor objects' Charikloan Chironean Haumean Quaoarian
Formation, evolution, contents, and History	Star formation Accretion Accretion disk Excretion Capture theory Capture of Triton Circumplanetary disk Circumstellar disc Circumstellar envelope Coatlicue Co-orbital configuration Trojan moons Co-orbital moons Cosmic dust Debris disk Detached object Disk instability EXCEDE Exozodiacal dust Extraterrestrial materials Curation Sample-return mission Frost/Ice/Snow line Giant-impact hypothesis Grand tack hypothesis Gravitational collapse Hills cloud Hill sphere Interplanetary dust cloud Interplanetary medium/space Interstellar cloud Interstellar medium Interstellar space Kuiper belt Kuiper cliff Late Heavy Bombardment Molecular cloud Nebular hypothesis Nice model Nice 2 model Five-planet Nice model Oort cloud Oort limit Outer space Planet Disrupted Migration System Planetesimal Formation Merging stars Protoplanetary disk Ring system Roche limit vs. Hill sphere Rubble pile Scattered disc
Small Solar System bodies	Asteroid belt Asteroids Ceres Vesta Pallas Hygiea active List families PHA exceptional Kirkwood gap Centaurs Comets Damocloids Meteoroids Minor planets names and meanings moons Planetesimal Planetary orbit-crossers Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Trojans Venus Earth Mars Jupiter Trojan camp Greek camp Saturn Uranus Neptune Near-Earth objects NEAs Trans-Neptunian objects Kuiper belt Cubewanos Plutinos Detached objects Sednoids Scattered disc Hills cloud Oort cloud Oort limit
Related	Double planet Lagrange point Moonlet Syzygy Tidal locking

Solar System →Local Interstellar Cloud →Local Bubble →Gould Belt →Orion Arm →Milky Way →Milky Way subgroup →Local Group→Local Sheet→Virgo Supercluster→Laniakea Supercluster →Local Hole →Observable universe →Universe
Each arrow (→) may be read as "within" or "part of".

Modern impact events

On Earth

Pre-2000

Post-2000

OnMars

Impact events on Mars

OnJupiter

Lists

v t e Impact cratering on Earth
Impact crater Impact event
Lists	Worldwide Africa Antarctica Asia and Russia Australia Europe North America South America By country Possible
Confirmed ≥20 km diameter	Acraman Amelia Creek Araguainha Beaverhead Boltysh Carswell Charlevoix Chesapeake Bay Chicxulub Clearwater East and West Gosses Bluff Haughton Kamensk Kara Karakul Keurusselkä Lappajärvi Logancha Manicouagan Manson Mistastin Mjølnir Montagnais Morokweng Nördlinger Ries Obolon' Popigai Presqu'île Puchezh-Katunki Rochechouart Saint Martin Shoemaker Siljan Ring Slate Islands Steen River Strangways Sudbury Tookoonooka Tunnunik Vredefort Woodleigh Yarrabubba
Topics	Alvarez hypothesis Australite Breccia Coesite Complex crater Cretaceous–Paleogene boundary Cryptoexplosion Ejecta blanket Impact crater Impact structure Impactite Late Heavy Bombardment Lechatelierite Meteorite Moldavite Ordovician meteor event Philippinite Planar deformation features Shatter cone Shock metamorphism Shocked quartz Stishovite Suevite Tektite
Research	Ralph Belknap Baldwin Daniel Barringer Barringer Medal Edward C. T. Chao Robert S. Dietz William Kenneth Hartmann H. Jay Melosh Graham Ryder Peter H. Schultz Eugene Merle Shoemaker Earth Impact Database Impact Field Studies Group Lunar and Planetary Institute Traces of Catastrophe

v t e Planetary defense
Main topics	Asteroid Bolide Earth-grazing fireball Impact event Meteor air burst Meteor procession Meteor shower Meteorite Meteoroid Near-Earth object Potentially hazardous object Earth-crossing minor planets Asteroid close approaches
Defense	Asteroid impact avoidance Asteroid laser ablation Gravity tractor Ion-beam shepherd
Space probes	Dawn Deep Impact HAMMER AIDA Hera DART Halley Armada Hayabusa Hayabusa2 MASCOT NEAR Shoemaker NEA Scout New Horizons OSIRIS-REx PROCYON Rosetta Philae Stardust
NEO tracking	ATLAS Catalina Sky Survey LINEAR LONEOS NEAT NEODyS NEO Surveyor NEOSSat OGS Telescope Orbit@home Pan-STARRS SCAP Sentinel Space Telescope Sentry Spacewatch WISE
Organizations	B612 Foundation Japan Spaceguard Association The Meteoritical Society NEOShield Planetary Defense Coordination Office Spaceguard The Spaceguard Foundation Space Situational Awareness Programme United Nations Office for Outer Space Affairs
Hazard rating	Torino scale Palermo scale
Potential threats	1950 DA 101955 Bennu 2010 RF₁₂ 99942 Apophis 2024 YR₄ List of objects with non-zero Torino ratings
Related categories	Impact events Fiction about meteoroids Fiction about impact events

Movatterモバイル変換

Overview

Levels of hazard

Potentially hazardous comet

Numbers

Size

Largest PHAs

Statistics

Gallery

See also

Notes

References

External links

Minor Planet Center