Potentially hazardous object

Short description: Hazardous near-Earth asteroid or comet

The asteroid Toutatis is listed as a potentially hazardous near-Earth asteroid, yet poses no immediate threat to Earth. (Radar image taken by GDSCC in 1996.)

A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and which is large enough to cause significant regional damage in the event of impact.[1] They are conventionally defined as having a minimum orbit intersection distance with Earth of less than 0.05 astronomical units (19.5 lunar distances) and an absolute 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 the Sentry 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 are potentially hazardous asteroids (PHAs), and a few are comets. 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 of largest PHAs below).[5][6][lower-alpha 1] Most of the discovered PHAs are Apollo asteroids (1,965) and fewer belong to the group of Aten 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 several astronomical surveys, the number of known PHAs has increased tenfold since the end of the 1990s (see bar charts below).[5] The Minor Planet Center's website List 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 a potential impactor, as most recently based on a simulated exercise conducted by the 2021 Planetary Defense Conference.[10][11][12]

## Contents

* 1 Overview
* 1.1 Levels of hazard
* 1.2 Potentially hazardous comet
* 1.3 Numbers
* 1.4 Size
* 2 Largest PHAs
* 2.1 Statistics
* 3 Gallery
* 4 See also
* 5 Notes
* 6 References
* 7 External links
* 7.1 Minor Planet Center

## Overview

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 its minimum orbit intersection distance (MOID) with respect to Earth is less than 0.05 astronomical unit|AU (7,500,000 km; 4,600,000 mi) – approximately 19.5 lunar distances – and its absolute 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 major tsunami in the case of an ocean 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

Main articles: Astronomy:Torino scale and Palermo scale

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

### Potentially hazardous comet

A potentially 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, and 73P/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

Detected NEAs by various projects. The broader class of NEAs includes all PHAs as a subset.[5] LINEAR
NEAT
Spacewatch
LONEOS
CSS |  Pan-STARRS
NEOWISE
ATLAS
Others

|

In 2012 NASA 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 gravitational perturbation, 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.

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

### Size

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 reason NASA and the Jet Propulsion Laboratory use the more practical measure of absolute 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 its albedo which is also not usually known for certain. The NASA near-Earth object program uses an assumed albedo of 0.14 for this purpose. In May 2016, the asteroid size estimates arising from the Wide-field Infrared Survey Explorer and NEOWISE 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

With a mean diameter of approximately 7 kilometers, Apollo asteroid (53319) 1999 JM8 is likely the largest known potentially hazardous object, despite its fainter absolute 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

|
|
|
|
|
|

Year | Place | Discoverer | Class | a
(AU) | e | i
(°) | q
(AU) | Q
(AU) | MOID
(AU)
(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

Below is a list of the largest PHAs (based on absolute 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 * —

Script error: No such module "Chart".

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]

Script error: No such module "Chart".

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

## Gallery

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

## See also

* Asteroid impact avoidance
* Earth-grazing fireball
* Global catastrophic risk
* List of asteroid close approaches to Earth
* Astronomy:Sentry (monitoring system) - JPL program to monitor the Minor Planet Center's catalog for Earth impacts
* Astronomy:Spaceguard - Efforts to study asteroids that might impact Earth

## Notes

1. ↑ 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's Asteroid Size Estimator is a tool for a generic absolute magnitude-to-diameter conversion for an assumed geometric albedo.

## References

1. ↑ 1.0 1.1 Task Force on potentially hazardous Near Earth Objects (September 2000). Report of the Task Force on potentially hazardous Near Earth Objects. http://www.nss.org/resources/library/planetarydefense/2000-ReportOfTheTaskForceOnPotentiallyHazardousNearEarthObjects-UK.pdf. Retrieved 22 January 2018.
2. ↑ 2.0 2.1 2.2 "NEO Basics – Potentially Hazardous Asteroids (PHAs)". CNEOS NASA/JPL. https://cneos.jpl.nasa.gov/about/neo_groups.html.
3. ↑ (17 Sentry "risk-listed" PHAs / 2289 known PHAs) ≈ 0.74%
4. ↑ 4.0 4.1 "Sentry Risk Table". https://cneos.jpl.nasa.gov/sentry/. (Click "Use Unconstrained Settings" and select "H<=22" for list of PHAs)
5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 "Discovery Statistics – Cumulative Totals". CNEOS NASA/JPL. 7 January 2020. https://cneos.jpl.nasa.gov/stats/totals.html.
6. ↑ "Unusual Minor Planets – Overview". Minor Planet Center. https://minorplanetcenter.net/iau/lists/Unusual.html.
7. ↑ "JPL Small-Body Database Search Engine: PHAs and orbital class (APO)". JPL Solar System Dynamics. https://ssd.jpl.nasa.gov/sbdb_query.cgi?obj_group=pha;obj_kind=all;obj_numbered=all;ast_orbit_class=APO;OBJ_field=0;ORB_field=0;table_format=HTML;max_rows=100;format_option=comp;c_fields=AcBhBgBjBiBnBsCjCpAi;.cgifields=format_option;.cgifields=obj_kind;.cgifields=obj_group;.cgifields=obj_numbered;.cgifields=ast_orbit_class;.cgifields=table_format;.cgifields=com_orbit_class&query=1&c_sort=AcA.
8. ↑ "JPL Small-Body Database Search Engine: PHAs and orbital class (ATE)". JPL Solar System Dynamics. https://ssd.jpl.nasa.gov/sbdb_query.cgi?obj_group=pha;obj_kind=all;obj_numbered=all;ast_orbit_class=ATE;OBJ_field=0;ORB_field=0;table_format=HTML;max_rows=100;format_option=comp;c_fields=AcBhBgBjBiBnBsCjCpAi;.cgifields=format_option;.cgifields=obj_kind;.cgifields=obj_group;.cgifields=obj_numbered;.cgifields=ast_orbit_class;.cgifields=table_format;.cgifields=com_orbit_class&query=1&c_sort=AcA.
9. ↑ 9.0 9.1 9.2 "List of the Potentially Hazardous Asteroids (PHAs)". Minor Planet Center. https://www.minorplanetcenter.net/iau/lists/t_phas.html.
10. ↑ 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. https://www.businessinsider.com/nasa-asteroid-simulation-reveals-need-years-of-warning-2021-5. Retrieved 14 May 2021.
11. ↑ Bartels, Meghan (1 May 2021). "How did you spend your week? NASA pretended to crash an asteroid into Earth.". Space.com. https://www.space.com/planetary-defense-asteroid-impact-scenario-exercise-2021. Retrieved 14 May 2021.
12. ↑ 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. https://cneos.jpl.nasa.gov/pd/cs/pdc21/. Retrieved 14 May 2021.
13. ↑ 13.0 13.1 "NASA news – NASA Survey Counts Potentially Hazardous Asteroids". NASA/JPL. 16 May 2012. https://www.jpl.nasa.gov/news/news.php?release=2012-138.
14. ↑ Will Ferguson (22 January 2013). "Asteroid Hunter Gives an Update on the Threat of Near-Earth Objects". Scientific American. https://blogs.scientificamerican.com/observations/asteroid-hunter-gives-an-update-on-the-threat-of-near-earth-objects/. Retrieved 2013-01-23.
15. ↑ Chang, Kenneth (23 May 2016). "How Big Are Those Killer Asteroids? A Critic Says NASA Doesn't Know.". The New York Times. https://www.nytimes.com/2016/05/24/science/asteroids-nathan-myhrvold-nasa.html.
16. ↑ 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].
17. ↑ Billings, Lee (27 May 2016). "For Asteroid-Hunting Astronomers, Nathan Myhrvold Says the Sky Is Falling". Scientific American. http://www.scientificamerican.com/article/for-asteroid-hunting-astronomers-nathan-myhrvold-says-the-sky-is-falling1/.
18. ↑ NASA Administrator (25 May 2016). "NASA Response to Recent Paper on NEOWISE Asteroid Size Results". NASA. https://www.nasa.gov/feature/nasa-response-to-recent-paper-on-neowise-asteroid-size-results.
19. ↑ Myhrvold, Nathan (2018). "An empirical examination of WISE/NEOWISE asteroid analysis and results". Icarus 314: 64–97. doi:10.1016/j.icarus.2018.05.004. Bibcode: 2018Icar..314...64M.
20. ↑ 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. https://www.nytimes.com/2018/06/14/science/asteroids-nasa-nathan-myhrvold.html.

## External links

* 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

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

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* Trans-Neptunian objects

* Plutoids
* Kuiper belt
* Cubewanos
* Plutinos
* Detached objects
* Hills cloud
* Oort cloud
* Scattered disc
* Sednoids

|

Formation
and evolution|

* Accretion
* Accretion disk
* Asteroid belt
* Circumplanetary disk
* Circumstellar disc
* Circumstellar envelope
* Cosmic dust
* Debris disk
* Detached object
* Disrupted planet
* Excretion disk
* Exoplanetary Circumstellar Environments and Disk Explorer
* Exozodiacal dust
* Extraterrestrial materials
* Extraterrestrial sample curation
* Giant-impact hypothesis
* Gravitational collapse
* Hills cloud
* Interplanetary dust cloud
* Interplanetary medium
* Interplanetary space
* Interstellar cloud
* Interstellar dust
* Interstellar medium
* Interstellar space
* Kuiper belt
* List of interstellar and circumstellar molecules
* Merging stars
* Molecular cloud
* Nebular hypothesis
* Oort cloud
* Outer space
* Planetary migration
* Planetary system
* Planetesimal
* Planet formation
* Protoplanetary disk
* Ring system
* Rubble pile
* Sample-return mission
* Scattered disc
* Star formation

* Outline of the Solar System
*   *   *

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

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Modern impact events

On Earth|

| Pre-2000|

* 1490 Ch'ing-yang
* 1783 Great Meteor
* 1860 Great Meteor
* 1896 Madrid Meteor
* 1908 Tunguska
* 1913 Great Meteor Procession
* 1930 Curuçá River
* 1938 Chicora meteor
* 1947 Sikhote-Alin meteorite
* 1969 Murchison meteorite
* 1972 Great Daylight Fireball
* 1990 Earth-grazing meteoroid

|

Post-2000|

* 2002 Eastern Mediterranean
* 2002 Vitim
* 2007 Carancas
* 2008 TC3 impact
* 2008 Buzzard Coulee meteorite
* 2009 Sulawesi superbolide
* 2012 Sutter's Mill meteorite
* 2012 UK meteoroid
* 2012 Novato meteorite
* 2013 Chelyabinsk meteor
* Chelyabinsk meteorite
* 2014 AA impact
* 2014 Ontario fireball
* 2015 Kerala meteorite
* 2015 Thailand bolide
* WT1190F impact
* 2017 China bolide
* 2018 LA impact
* 2018 Kamchatka meteor
* 2019 MO impact

On Jupiter|

* 1994 Comet Shoemaker–Levy 9
* 2009 Jupiter impact
* 2010 Jupiter impact

Lists|

* Asteroid close approaches to Earth
* Comets
* Bolides
* Meteor air bursts
* Meteorite falls
* Minor planets
* crossing Earth's orbit

See also|

* Asteroid impact prediction
* Asteroid impact avoidance
* Bolide
* Earth-grazing fireball
* Meteor procession
* Meteor shower
* Meteorite
* Meteoroid
* Near-Earth object
* Potentially hazardous object

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* e

Impact cratering on Earth

* Impact crater
* Impact event

Lists|

* Worldwide
* Africa
* Antarctica
* Asia
* Australia
* Europe
* North America
* South America
* By country

Confirmed

≥20 km diameter|

* Acraman
* Amelia Creek
* Araguainha
* Beaverhead
* Boltysh
* Carswell
* Charlevoix
* Chesapeake Bay
* Chicxulub
* Clearwater East & 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|

* Baldwin, Ralph Belknap
* Barringer, Daniel
* Barringer Medal
* Chao, Edward C T
* Dietz, Robert S
* Hartmann, William K
* Melosh, H Jay
* Ryder, Graham
* Schultz, Peter H
* Shoemaker, Eugene
* Earth Impact Database
* Impact Field Studies Group
* Lunar and Planetary Institute
* Traces of Catastrophe

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* e

Planetary defense

Main topics|

* Asteroid
* Bolide
* Earth-grazing fireball
* Impact event
* List of meteor air bursts
* Meteor procession
* Meteor shower
* Meteorite
* Meteoroid
* Near-Earth object
* Potentially hazardous object

Defense|

* Asteroid impact avoidance
* Asteroid laser ablation
* Gravity tractor
* Ion-beam shepherd
* Asteroid close approaches
* Earth-crossing minor planets
* Damage scales
* Palermo scale
* Torino scale

Space probes|

* Dawn
* Deep Impact
* 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
* NEOSSat
* NEOCam
* NEODyS
* OGS Telescope
* Orbit@home
* Pan-STARRS
* SCAP
* Sentinel Space Telescope
* Sentry
* Spacewatch
* WISE

Organizations|

* B612 Foundation
* Japan Spaceguard Association
* Meteoritical Society
* NEOShield
* Spaceguard
* The Spaceguard Foundation
* Space Situational Awareness Programme
* Planetary Defense Coordination Office

Potential threats|

* 1950 DA
* 1994 WR12
* 101955 Bennu
* 2002 MN
* (410777) 2009 FD
* 2010 RF12
* 99942 Apophis

Films / video|

* The End of the World (1916)
* When Worlds Collide (1951)
* Gorath (1962)
* The Green Slime (1968)
* The Paradise Syndrome (1968)
* A Fire in the Sky (1978)
* Meteor (1979)
* NOVA: Doomsday Asteroid (1995)
* Asteroid (1997)
* Deep Impact (1998)
* Armageddon (1998)
* Judgment Day (1999)
* Post Impact (2004)
* Deadly Skies (2006)
* Super Comet: After the Impact (2007)
* Impact (2009)
* NOVA: Last Extinction (2009)
* Meteor Storm (2010)
* HORIZON: Asteroids–The Good, the Bad and the Ugly (2010)
* Melancholia (2011)
* NOVA: Meteor Strike (2013)
* NOVA: Asteroid: Doomsday or Payday? (2013)
* Impact Earth (2015)
* Avengers: Age of Ultron (2015)

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* e

Global catastrophic risks

* Future of the Earth
* Ultimate fate of the universe

Technological|

* Gray goo
* Kinetic bombardment
* Mutual assured destruction
* Dead Hand
* Doomsday device
* Antimatter weapon
* Synthetic intelligence / Artificial intelligence
* Existential risk from artificial intelligence
* AI takeover
* Technological singularity
* Transhumanism
* Year 2000 problem

Sociological|

* Malthusian catastrophe
* New World Order (conspiracy theory)
* Nuclear holocaust
* winter
* famine
* cobalt
* Societal collapse
* World War III

Ecological|

| Climate change|

* Extinction risk from global warming
* Tipping points in the climate system
* Global terrestrial stilling
* Global warming
* Hypercane
* Ice age
* Ecocide
* Human impact on the environment
* Ozone depletion
* Cascade effect
* Supervolcano
* winter

|

Earth Overshoot Day|

* Overexploitation
* Overpopulation
* Human overpopulation

Biological|

| Extinction|

* Extinction event
* Human extinction
* Genetic erosion
* Genetic pollution

|

Others|

* Dysgenics
* Pandemic
* Biological agent
* Transhumanism

Astronomical|

* Big Crunch
* Big Rip
* Coronal mass ejection
* Gamma-ray burst
* Impact event
* Asteroid impact avoidance
* Potentially hazardous object
* Near-Earth supernova
* Solar flare
* Stellar collision

Mythological|

| Eschatology|

* Buddhist
* Hindu
* Last Judgment
* Christian
* Book of Revelation
* Islamic
* Jewish
* Norse
* Zoroastrian

|

Others|

* 2011 end times prediction
* 2012 phenomenon
* Apocalypse
* Armageddon
* Blood moon prophecy
* Doomsday Clock
* End time
* List of dates predicted for apocalyptic events
* Nibiru cataclysm
* Rapture
* Revelation 12 sign prophecy
* Third Temple

Fictional|

* Alien invasion
* Apocalyptic and post-apocalyptic fiction
* List of apocalyptic and post-apocalyptic fiction
* List of apocalyptic films
* Climate fiction
* Disaster films
* List of disaster films
* List of fictional doomsday devices
* Zombie apocalypse

* Categories
* Apocalypticism
* Future problems
* Hazards
* Risk analysis
* Doomsday scenarios

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Original source: https://en.wikipedia.org/wiki/Potentially hazardous object. Read more

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