1991 BA
Small risk–listed near-Earth asteroid
title: "1991 BA" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["apollo-asteroids", "minor-planet-object-articles-(unnumbered)", "near-earth-objects-in-1991", "lost-minor-planets", "potential-impact-events-caused-by-near-earth-objects", "astronomical-objects-discovered-in-1991"] description: "Small risk–listed near-Earth asteroid" topic_path: "general/apollo-asteroids" source: "https://en.wikipedia.org/wiki/1991_BA" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Small risk–listed near-Earth asteroid ::
::data[format=table title="Infobox planet"]
| Field | Value |
|---|---|
| minorplanet | yes |
| name | 1991 BA |
| background | #FFC2E0 |
| discovery_ref | |
| discovered | 18 January 1991 |
| discoverer | Spacewatch |
| discovery_site | Kitt Peak Obs. |
| mpc_name | 1991 BA |
| mp_category | ApolloNEO |
| orbit_ref | |
| epoch | 18 January 1991 (JD 2448274.5) |
| uncertainty | 9 |
| observation_arc | 4.6 hours |
| aphelion | |
| perihelion | |
| semimajor | |
| eccentricity | |
| period | yr ( days) |
| mean_anomaly | |
| mean_motion | / day |
| inclination | |
| asc_node | |
| arg_peri | |
| moid | 0.0003 AU0.1 LD |
| dimensions | 5–10 m |
| abs_magnitude | 28.6 |
| :: |
| minorplanet = yes | name = 1991 BA | background = #FFC2E0 | image = | image_size = | caption = | discovery_ref = | discovered = 18 January 1991 | discoverer = Spacewatch | discovery_site = Kitt Peak Obs. | mpc_name = 1991 BA | mp_category = ApolloNEO | orbit_ref = | epoch = 18 January 1991 (JD 2448274.5) | uncertainty = 9 | observation_arc = 4.6 hours | aphelion = | perihelion = | semimajor = | eccentricity = | period = yr ( days) | mean_anomaly = | mean_motion = / day | inclination = | asc_node = | arg_peri = | moid = 0.0003 AU0.1 LD | dimensions = 5–10 m | abs_magnitude = 28.6
1991 BA is a sub-kilometer asteroid, classified as near-Earth object of the Apollo group that was first observed by Spacewatch on 18 January 1991, and passed within 160,000 km of Earth.
Description
1991 BA is approximately 5 to in diameter and is listed on the Sentry Risk Table. It follows a highly eccentric (0.68), low-inclination (2.0°) orbit of 3.3 years duration, ranging between 0.71 and 3.7 AU from the Sun. 1991 BA was, at the time of its discovery, the smallest and closest confirmed asteroid outside of Earth's atmosphere. 1991 BA is too faint to be observed except during close approaches to Earth and is considered lost.
Possible impact
The asteroid has a very short 5-hour observation arc that makes future predictions of its position unreliable. Virtual clones of the asteroid that fit the uncertainty region in the known trajectory use to show a 1 in 290,000 chance that the asteroid could impact Earth on 2023 January 18. It is estimated that an impact would produce an upper atmosphere air burst equivalent to 16 kt TNT, Asteroid was an object of similar size that was discovered less than a day before its impact on Earth on October 7, 2008, and produced a fireball and meteorite strewn field in the Sudan. The 18 January 2023 virtual impactor did not occur.
::data[format=table title="Virtual impactor"] | Date | Impact probability (1 in) | JPL Horizons nominal geocentric distance (AU) | NEODyS nominal geocentric distance (AU) | MPC nominal geocentric distance (AU) | Find_Orb nominal geocentric distance (AU) | uncertainty region (3-sigma) | |---|---|---|---|---|---|---| | 2023-01-18 | | 3.9 AU | 3.9 AU | 2.4 AU | 2.8 AU | ± 841 million km | ::
There is a 1 in a million chance of impacting Earth on 19 January 2114.
References
|type = 1991-01-18 last obs. |title = JPL Small-Body Database Browser: (1991 BA) |url = http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=3092104 |publisher = Jet Propulsion Laboratory |accessdate = 2 August 2017}}
|title = 1991 BA |work = Minor Planet Center |url = http://www.minorplanetcenter.net/db_search/show_object?object_id=1991+BA |accessdate = 2 August 2017}}
|type=last observation: 1991-01-18; arc: 1 day; uncertainty: 9 |title=JPL Close-Approach Data: (1991 BA) |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1991BA;cad=1#cad |accessdate=2012-03-20}}
|title=Earth Impact Risk Summary: 1991 BA |publisher=NASA/JPL Near-Earth Object Program Office |url=https://cneos.jpl.nasa.gov/sentry/details.html#?des=1991%20BA |archiveurl=https://web.archive.org/web/20110817035909/http://neo.jpl.nasa.gov/risk/1991ba.html |archivedate=2011-08-17 |url-status=live |accessdate=2012-03-10}}
|last=Scotti |first=J. V. |authorlink=James V. Scotti |author2=Rabinowitz, D. L. |author2-link=David L. Rabinowitz |author3=Marsden, B. G. |author3-link=Brian G. Marsden |title=Near miss of the Earth by a small asteroid |journal=Nature |volume=354 |pages=287–289 |date=1991 |issue=6351 |doi=10.1038/354287a0|bibcode = 1991Natur.354..287S }}
|title=Horizons Batch for 2023-01-18 Virtual Impactor |publisher=JPL Horizons |url=https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%271991+BA%27&START_TIME=%272023-01-18%27&STOP_TIME=%272023-01-19%27&STEP_SIZE=%272%20day%27&QUANTITIES=%2720,39%27 |archive-url=https://web.archive.org/web/20221109195513/https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%271991+BA%27&START_TIME=%272023-01-18%27&STOP_TIME=%272023-01-19%27&STEP_SIZE=%272%20day%27&QUANTITIES=%2720,39%27 |archive-date=2022-11-09 |url-status=live |accessdate=2021-11-09}} RNG_3sigma = uncertainty range in km. (JPL#12/Soln.date: 2021-Apr-15 generates RNG_3sigma = for 2023-Jan-18.)
|title=2009JF1 Ephemerides for 18 January 2023 |publisher=NEODyS (Near Earth Objects Dynamic Site) |url=https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=1991BA&oc=500&y0=2023&m0=01&d0=18&y1=2023&m1=01&d1=18&ti=1.0&tiu=days |archive-url=https://web.archive.org/web/20221109200240/https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=1991BA&oc=500&y0=2023&m0=01&d0=18&y1=2023&m1=01&d1=18&ti=1.0&tiu=days |archive-date=2022-11-09 |url-status=live |accessdate=2022-11-09}}
|title=MPC Ephemeris Service |publisher=IAU Minor Planet Center |url=https://minorplanetcenter.net//iau/MPEph/MPEph.html |accessdate=2022-11-09}}
|title=Find_Orb for 2023-01-18 |publisher=Project Pluto |url=https://www.projectpluto.com/cgi-bin/fo/fo_serve.cgi?obj_name=1991+BA&year=2022-01-18&n_steps=1&stepsize=1 |archive-url=https://web.archive.org/web/20221109200931/https://www.projectpluto.com/cgi-bin/fo/fo_serve.cgi?obj_name=1991+BA&year=2022-01-18&n_steps=1&stepsize=1 |archive-date=2022-11-09 |url-status=live |accessdate=2021-11-09}}
References
- This is a little less than half the distance to the [[Moon]]. With a 5-hour [[observation arc]] the asteroid has a poorly constrained orbit and is considered [[Lost minor planet|lost]]. It could be a member of the [[Beta Taurids]].[[Peter Jenniskens]] Meteor Showers and their Parent Comets pg 463 fig 25.7
- "Asteroid Fast Facts".
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