 2019 OK orbits near the ecliptic plane out to the asteroid belt and inside the orbit of Venus | |
| Discovery[1] | |
|---|---|
| Discovered by | SONEAR Obs. |
| Discovery site | SONEAR Obs. (Y00) |
| Discovery date | 24 July 2019 |
| Designations | |
| 2019 OK | |
| NEOCP S511618[2] | |
| Apollo · NEO | |
| Orbital characteristics[3] | |
| Epoch 27 April 2019 (JD 2458600.5) | |
| Uncertainty parameter 1 | |
| Observation arc | 2.42 years |
| Earliestprecovery date | 2017-02-21 (Pan-STARRS) |
| Aphelion | 3.4315AU |
| Perihelion | 0.4635 AU |
| 1.9475 AU | |
| Eccentricity | 0.7620 |
| 2.72yr (993 d) | |
| 310.58° | |
| 0° 21m 45.36s / day | |
| Inclination | 1.4006° |
| 302.27° | |
| 104.24° | |
| Earth MOID | 0.00036 AU (54,000 km) (0.14LD) |
| Physical characteristics | |
| 57–130 m (187–426 ft) | |
| 23.3±0.3[3] 23.3[1] | |
2019 OK[a] is anear-Earth asteroid noted for its sudden, surprise discovery on the day before itflew by at approximately 70,000 km (43,000 mi) in 2019.[4] The object's size is estimated at 57 to 130 metres (187 to 426 ft) across, the closest asteroid of such size discovered in 2019.[5] It is uncommon for asteroids of this moderately large size to pass within 100,000 km (62,000 mi) of Earth.
The first detection made public occurred on 24 July 2019, when it was 0.01 AU (1,500,000 km; 930,000 mi) from Earth and had an apparent magnitude of 14.7.[6] The full moon on 16 July 2019 slowed down the asteroid discovery rate during mid-July. The asteroid was detected by Cristóvão Jacques, Eduardo Pimentel and João Ribeiro at the private SONEAR Observatory inOliveira, Minas Gerais when it was very close toopposition (opposite the Sun in the sky) with asolar elongation of 170 degrees. About 10 hours later it was independently detected byASAS-SN project in images from two of its telescopes, which allowed a preliminary determination of its orbit. It was subsequently listed on theMinor Planet Center'sNear-Earth Object Confirmation Page (NEOCP) as S511618. The listing was confirmed and publicly announced as2019 OK with three hours remaining before the 25 July 2019 closest approach.[6]
Various circumstances prevented an earlier discovery, despite the efforts to continuously hunt for such objects. The last previous appearance was not lost in the glare of the Sun, but was not favorable to survey instruments located in the Northern Hemisphere, due to its celestial direction in the SouthernconstellationCapricornus and close to the bright moon. ThePan-STARRS1 telescope did record an image of 2019 OK on 28 June 2019 when it was 0.39 AU (58,000,000 km; 36,000,000 mi) from Earth and had anapparent magnitude of 22.9.[6] Automatic analysismissed detecting the object in the Pan-STARRS image because the object was too faint. ThePan-STARRS1 telescope again saw the object on 7 July 2019 when the object was brighter with magnitude 21.2. However, it was at that time moving directly towards the observer and its apparent motion across the sky was extremely slow, with a rate of 0.01 degrees/day, and it was not recognized as a moving object.[7]
The asteroid is a member of theFlora family (402), a populousasteroid family and the largest family of stony asteroids in the main-belt.[8] It orbits the Sun in theinner main-belt at a distance of 0.5–3.4 AU once every 2 years and 9 months (993 days;semi-major axis of 1.95 AU). Its orbit has aneccentricity of 0.76 and aninclination of 1° with respect to theecliptic.[3] After evaluating its orbit, the asteroid was identified as the most probableparent body of the particles responsible for themeteor shower designated, 17 Capricornids (SCP #1042).[9]
On 25 July 2019 at 01:22UTC it had its closest approach toEarth, when it passed about 0.00047697 AU (71,354 km; 44,337 mi)—less than one-fifth of the distance to theMoon.[3] Its speed was nearly 88,500 kilometres (55,000 mi) per hour.[10][11]
On 28 July 2116 the asteroid will pass about 0.03 AU (4,500,000 km; 2,800,000 mi) from Earth.[3]
| Asteroid | Date | Distance (thousand km) | H | Diameter (meters) (albedo=0.15) |
|---|---|---|---|---|
| 2019 OK | 2019-07-25 | 71 | 23.3 | 75 |
| 2019 OD | 2019-07-24 | 357 | 23.5 | 68 |
| 2010 WC9 | 2018-05-15 | 202 | 23.6 | 65 |
| 2018 GE3 | 2018-04-15 | 192 | 23.8 | 60 |
| 2018 AH | 2018-01-02 | 296 | 22.5 | 110 |
| 367943 Duende | 2013-02-15 | 34 | 24.0 | 54 |
| 2011 XC2 | 2011-12-03 | 347 | 23.2 | 79 |
| (308635) 2005 YU55 | 2011-11-08 | 324 | 21.9 | 140 |
Asteroids in the 20 m (66 ft)Chelyabinsk meteor size range to 50 m (160 ft) Tunguska size range (absolute magnitude H ~26–24) approach closer than the Moon about once per month. Asteroids with an absolute magnitude of 26–24 will vary in size from 17 to 94 m (56 to 308 ft) depends on the objects albedo (how reflective it is).[12]
If 2019 OK is around 100 m (330 ft) in diameter, an Earth impact could have released as much power as the 50megatons generated by theTsar Bomba hydrogen bomb.[13] If 2019 OK is around the middle of the size estimates, it could instead have released the equivalent explosive energy of about 10 megatons of TNT similar to the 1908Tunguska event that flattened 2,000 km2 (770 square miles) of forest land.[11] If 2019 OK is on the smaller size it still could have released over 30 times the energy of the atomic blast byLittle Boy at Hiroshima.[14]
