2019 MO, temporarily designated A10eoM1, was a small, harmless 3-meter near-Earth asteroid discovered by ATLAS–MLO that impacted Earth's atmosphere on 22 June 2019 at 21:25 UT. The impact of the

bolide A bolide is normally taken to mean an exceptionally bright meteor, but the term is subject to more than one definition, according to context. It may refer to any large Impact crater, crater-forming body, or to one that explodes in the atmosphere. ...

generated a 5-kiloton-equivalent explosion off the south coast of

Puerto Rico ; abbreviated PR), officially the Commonwealth of Puerto Rico, is a Government of Puerto Rico, self-governing Caribbean Geography of Puerto Rico, archipelago and island organized as an Territories of the United States, unincorporated territo ...

which was detected by

infrasound Infrasound, sometimes referred to as low frequency sound or incorrectly subsonic (subsonic being a descriptor for "less than the speed of sound"), describes sound waves with a Audio frequency, frequency below the lower limit of human audibility ...

detectors. The strewn field would be spread over the

Caribbean Sea The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

. The Apollo asteroid was inbound approaching a late July

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

(closest approach to the Sun) when it impacted Earth at 16.1 km/s.

Overview

The asteroid was discovered by ATLAS–MLO on 22 June 2019 and was observed four times with an

observation arc In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...

of just 30 minutes, typical for ATLAS discoveries before they are followed up by other resources. With such a short observation arc, how far away (and, therefore, how large) the object is very uncertain until more data are available. Using these four observations, JPL's

Scout Scout may refer to: Youth movement *Scout (Scouting), a child, usually 10–18 years of age, participating in the worldwide Scouting movement ** Scouts (The Scout Association), section for 10-14 year olds in the United Kingdom ** Scouts BSA, sect ...

listed the impact risk as modest, and calculated that the asteroid was about 160 meters in diameter and would pass about 36 LD (14 million km) from Earth. A fireball was however reported. When the Caribbean bolide report came in from the GOES-16

weather satellite A weather satellite or meteorological satellite is a type of Earth observation satellite that is primarily used to monitor the weather and climate of the Earth. Satellites are mainly of two types: polar orbiting (covering the entire Earth asyn ...

it was possible to link the ATLAS

astrometry Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other Astronomical object, celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, th ...

to it. Three additional precovery observations by

Pan-STARRS The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1; List of observatory codes, obs. code: IAU code#F51, F51 and Pan-STARRS2 obs. code: IAU code#F52, F52) located at Haleakala Observatory, Hawaii, US, consists of astronomical ...

2 were then located and extended the observation arc to 2.3 hours. Using all seven observations, Scout then obtained a significantly better orbit determination with an impact rating of "elevated". The updated orbit shows that the asteroid was about 1.3 LD (500,000 km) from Earth when ATLAS-MLO observed it, 12 hours before impact.

Visibility

The asteroid came to opposition 175 degrees from the Sun on 17 May 2019 when it had an apparent magnitude of 27. Such a faint apparent magnitude would require a 10-hour image to detect with the largest 8-meter class telescopes in the world. Pan-STARRS is a 1.8-meter class telescope and with 30 second images has a limiting apparent magnitude of around 22. ATLAS has a limiting apparent magnitude closer to 19. The asteroid first became brighter than apparent magnitude 23 on 19 June, when it was about 4 million km from Earth. The asteroid was detected by ATLAS when it was apparent magnitude 18.1.

Meteorites

This bolide was a probable

meteorite fall A meteorite fall, also called an observed fall, is a meteorite collected after its fall from outer space, that was also observed by people or automated devices. Any other meteorite is called a "meteorite find, find". There are more than 1,300 d ...

into waters 4.8 km deep.

NEXRAD NEXRAD or Nexrad (Next-Generation Radar) is a network of 159 high-resolution S-band pulse-Doppler radar, Doppler weather radars operated by the National Weather Service (NWS), an agency of the National Oceanic and Atmospheric Administration (NOAA) ...

weather radar detected falling meteorites at 21:26:15 UT at 10.6 km above sea level. Signatures consistent with falling meteorites appear in a total of four radar sweeps. Meteorite falls with enough mass to generate green pixels on weather radar are very rare.

Origin

It could be an Alinda asteroid originating from the 3:1

mean-motion resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relation ...

with Jupiter. Even though 2019 MO has a geometric similarity to the June epsilon Ophiuchids and four other minor meteor showers, it could just as easily be a sporadic meteor that just looks similar by chance. 2019 MO is about 12° away from the concentration of June epsilon Ophiuchids orbits.

Notes

References

External links

* * * {{DEFAULTSORT:2019 MO Alinda asteroids Discoveries by ATLAS Minor planet object articles (unnumbered) Modern Earth impact events 2019 in outer space 20190622 20190622 Predicted impact events