 Orbital diagram of2019 MO on 22 June 2019 | |
| Discovery [1][2] | |
|---|---|
| Discovered by | ATLAS–MLO (T08) |
| Discovery site | Mauna Loa Obs. |
| Discovery date | 22 June 2019 |
| Designations | |
| 2019 MO | |
| NEOCP A10eoM1 | |
| NEO · Apollo [2][3] Alinda | |
| Orbital characteristics [3] | |
| Epoch 22 June 2019 (JD 2458656.5) | |
| Uncertainty parameter 9 [3] · 7 [2] | |
| Observation arc | 2.3 h(approx.)[4] |
| Aphelion | 4.0116AU |
| Perihelion | 0.9384 AU |
| 2.4750 AU | |
| Eccentricity | 0.6208 |
| 3.89yr (1,422 d) | |
| 352.63° | |
| 0° 15m 11.16s / day | |
| Inclination | 1.5471° |
| 91.040° | |
| 2019-Jul-21 | |
| 216.76° | |
| Earth MOID | 4.54412×10−7 AU (67.9791 km) |
| Physical characteristics | |
| 3 m[5] | |
| 29.3[2][3] | |
2019 MO, temporarily designated A10eoM1, was a small, harmless 3-meternear-Earth asteroid discovered byATLAS–MLO thatimpacted Earth's atmosphere on 22 June 2019 at 21:25UT.[3][4][5][6] The impact of thebolide generated a 5-kiloton-equivalent explosion off the south coast of Puerto Rico which was detected byinfrasound detectors.[5] Thestrewn field would be spread over theCaribbean Sea.[7]
TheApollo asteroid was inbound approaching a late Julyperihelion (closest approach to the Sun) when it impacted Earth at 16.1 km/s.[8]
The asteroid was discovered byATLAS–MLO on 22 June 2019 and was observed four times with anobservation arc 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'sScout listed the impact risk as modest,[7] and calculated that the asteroid was about 160 meters[a] in diameter and would pass about 36LD (14 million km) from Earth.[9] Afireball was however reported.[3] When the Caribbean bolide report came in from theGOES-16weather satellite it was possible to link the ATLASastrometry to it. Three additionalprecovery observations byPan-STARRS 2 were then located and extended the observation arc to 2.3 hours. Using all seven observations, Scout then obtained a significantly betterorbit determination with an impact rating of "elevated".[7] The updated orbit shows that the asteroid was about 1.3LD (500,000 km) from Earth when ATLAS-MLO observed it, 12 hours before impact.
The asteroid came toopposition 175 degrees from the Sun on 17 May 2019 when it had anapparent magnitude of 27.[10] 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.[b] 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.[1]
This bolide was a probablemeteorite fall into waters 4.8 km deep.NEXRAD weather radar detected falling meteorites at 21:26:15 UT at 10.6 km above sea level.[11] 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.
It could be anAlinda asteroid originating from the 3:1mean-motion resonance with Jupiter.[citation needed] Even though 2019 MO has a geometric similarity to theJune epsilon Ophiuchids and four other minor meteor showers, it could just as easily be a sporadic meteor that just looks similar by chance.[12] 2019 MO is about 12° away from the concentration of June epsilon Ophiuchids orbits.
The few other asteroids discovered before impacting are2008 TC3,2014 AA,2018 LA,2022 EB5 and2022 WJ1.
