2022 AP7 was discovered as part of Sheppard's twilight survey for near-Earth asteroids interior to Earth and Venus, using Cerro Tololo Observatory's Dark Energy Camera.[1] Notable discoveries from this survey include the Atira asteroids2021 LJ4 and 2021 PH27, the latter of which holds the record for the shortest orbital period of any known asteroid as of 2022[update].[4]
Orbit and classification
2022 AP7 is considered "potentially hazardous" only because of its large size and low Earth minimum orbit intersection distance (MOID) just within 0.05 AU (7.5 million km; 19 LD).[3][4] However, the asteroid does not currently make notable close approaches to Earth because it is in a 1:5 near orbital resonance with Earth,[8] which means it nearly takes exactly 5.0 years to orbit the Sun in a highly elliptical orbit.[3] This resonance regularly puts it in positions where observational conditions are unfavorable; the asteroid is obscured by the Sun's glare when it becomes brightest near perihelion at low solar elongations and can be fainter at opposition when it is farther from Earth.[4] As a result, 2022 AP7 could only be efficiently searched at twilight when at its brightest; the asteroid was 45 degrees from the Sun and 1.9 AU from Earth when it was discovered.[4][9] The asteroid made its closest approach 1.47 AU from Earth on 7 March 2022.[10] The asteroid will not come this close to Earth again until March 2027.[11] By May 2022, when the asteroid was 1 AU from the Sun and near the ecliptic, Earth was on the other side of the Sun, 1.9 AU from the asteroid.[12]
The asteroid is not risk listed. 2022 AP7's orbit is well-determined and will guarantee only distant approaches beyond 1.1 AU (160 million km; 430 LD) of Jupiter over the next 146 years.[3][8] The asteroid will also pass 0.16 AU (24 million km; 62 LD) from Mars on 9 May 2107.[13] Nominally the asteroid will not approach 1 AU from Earth until April 2332.[14] Over the next several centuries if not thousands of years, repeated perturbations by these encounters will eventually break the 1:5 near orbital resonance of 2022 AP7, potentially leading to an impact with Earth.[15]
2022 AP7 Closest Approaches 2022–2150 (Earth has the farthest approach)
^An absolute magnitude of 17.3 and assumed albedo of 0.14 gives a diameter of 1,231 m (1.231 km) (or ≈1.2 km after rounding). PHAs brighter than absolute magnitude 17.75 are likely larger than 1 km in size.
^2014 LJ21 was discovered on 5 June 2014 and has an absolute magnitude of 16.05[6] with an estimated diameter of ≈2.2 km. Another potentially hazardous asteroid similar in size to 2022 AP7 is 2022 RX3 (absolute magnitude of 17.64)[7] estimated to be ≈1.1 km in diameter.
Scott Gleeson; Jordan Mendoza (1 November 2022). "'Planet killer' asteroids nearly a mile long detected after being hidden by the sun's brightness". USA Today. 'It remains very far from Earth, kind of locked in a resonance that keeps it as being actually one of the most distant of the asteroids that we categorize as potentially hazardous.' ... 2022 AP7 is only projected to have close approaches to Mars and Jupiter in the next 145 years [not Earth].
