2019 MO, temporarily designated A10eoM1, was a small, harmless 3-meter

near-Earth asteroid A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). ...

discovered by ATLAS–MLO that impacted Earth's atmosphere on 22 June 2019 at 21:25 UT. The impact of the bolide generated a 5-kiloton-equivalent explosion off the south coast of Puerto Rico which was detected by infrasound detectors. The strewn field would be spread over the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

. The Apollo asteroid was inbound approaching a late July perihelion (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, sectio ...

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 Fireball may refer to: Science * Fireball (meteor), a brighter-than-usual meteor * Ball lightning, an atmospheric electrical phenomenon * ''Bassia scoparia'', a plant species Arts and entertainment Films * ''The Fireball'', a 1950 film starring ...

was however reported. When the Caribbean bolide report came in from the

GOES-16 GOES-16, formerly known as GOES-R before reaching geostationary orbit, is the first of the GOES-R series of Geostationary Operational Environmental Satellites (GOES) operated by NASA and the National Oceanic and Atmospheric Administration&n ...

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 can be polar orbiting (covering the entire Earth asynchronously), or ge ...

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 celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. His ...

to it. Three additional

precovery In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of an object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This happens mos ...

observations by Pan-STARRS 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 Opposition may refer to: Arts and media * ''Opposition'' (Altars EP), 2011 EP by Christian metalcore band Altars * The Opposition (band), a London post-punk band * ''The Opposition with Jordan Klepper'', a late-night television series on Comed ...

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 was observed by people or automated devices. Any other meteorite is called a "find". There are more than 1,100 documented falls listed in w ...

into waters 4.8 km deep. NEXRAD 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 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. The few other asteroids discovered before impacting are ,

2014 AA 2014 AA was a small Apollo near-Earth asteroid roughly 2–4 meters in diameter that struck Earth on 2 January 2014. It was discovered on 1 January 2014 by Richard Kowalski at the Mount Lemmon Survey at an apparent magnitude of 19 using a reflec ...

2018 LA 2018 LA, also known as ZLAF9B2, was a small Apollo asteroid, Apollo near-Earth asteroid in mean diameter that impacted the atmosphere with small fragments reaching the Earth at roughly 16:44 UTC (18:44 local time) on 2 June 2018 near the border o ...

and .

Notes

References

External links

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