Minimum orbit intersection distance (MOID) is a measure used in astronomy to assess potential close approaches and collision risks between astronomical objects.[1][2] It is defined as the distance between the closest points of the osculating orbits of two bodies. Of greatest interest is the risk of a collision with Earth. Earth MOID is often listed on comet and asteroid databases such as the JPL Small-Body Database. MOID values are also defined with respect to other bodies as well: Jupiter MOID, Venus MOID and so on.
An object is classified as a potentially hazardous object (PHO) – that is, posing a possible risk to Earth – if, among other conditions, its Earth MOID is less than 0.05
A low MOID does not mean that a collision is inevitable as the planets frequently perturb the orbit of small bodies. It is also necessary that the two bodies reach that point in their orbits at the same time before the smaller body is perturbed into a different orbit with a different MOID value. Two objects gravitationally locked in orbital resonance may never approach one another. Numerical integrations become increasingly divergent as trajectories are projected further forward in time, especially beyond times where the smaller body is repeatedly perturbed by other planets. MOID has the convenience that it is obtained directly from the orbital elements of the body and no numerical integration into the future is used.[3]
The only object that has ever been rated at 4 on the Torino Scale (since downgraded), the Aten asteroid (99942) Apophis, has an Earth MOID of 0.00026
Object | Earth MOID ( |
Size (m) (approximate) |
(H) |
---|---|---|---|
2016 FG60 | 0.000076 |
300 | 21.1 |
(177049) 2003 EE16 | 0.000107 |
320 | 19.8 |
2012 HZ33 | 0.000131 |
260 | 20.4 |
2010 JE88 | 0.000148 |
180 | 21.5 |
(137108) 1999 AN10 | 0.000153 |
1300 | 17.9 |
2022 BX1 | 0.000177 |
170 | 21.7 |
2003 EG16 | 0.000179 |
490 | 19.4 |
2021 NQ5 | 0.000187 |
210 | 21.2 |
(442037) 2010 PR66 | 0.000238 |
695 | 19.3 |
(216985) 2000 QK130 | 0.000252 |
200 | 21.3 |
99942 Apophis | 0.000257 |
370 | 19.7 |
(89958) 2002 LY45 | 0.000261 |
1300 | 17.2 |
(35396) 1997 XF11 | 0.000305 |
704 | 17.0 |
162173 Ryugu | 0.000315 |
896 | 19.6 |
(143651) 2003 QO104 | 0.000321 |
2300 | 16.1 |
(85236) 1993 KH | 0.000335 |
500 | 18.8 |
(471240) 2011 BT15 | 0.000368 |
150 | 21.4 |
Object | Epoch | Earth MOID ( |
---|---|---|
3D/Biela | 1832 | 0.0005 |
109P/Swift-Tuttle | 1995 | 0.0009 |
55P/Tempel–Tuttle | 1998 | 0.0085 |
255P/Levy | 2007 | 0.0088 |
15P/Finlay | 2015 | 0.0092 |
73P–BW | 2022 | 0.0093 |
252P/LINEAR | 2016 | 0.0122 |
460P/PanSTARRS | 2016 | 0.0163 |
289P/Blanpain | 2019 | 0.0165 |
21P/Giacobini–Zinner | 2017 | 0.0179 |
Object | Earth MOID ( |
---|---|
6 Hebe | 0.975 |
7 Iris | 0.850 |
8 Flora | 0.873 |
12 Victoria | 0.824 |
18 Melpomene | 0.811 |
84 Klio | 0.798 |
228 Agathe | 0.657 |
See also edit
- Asteroid impact prediction
- List of Mercury-crossing minor planets
- List of Venus-crossing minor planets
- List of Earth-crossing minor planets
- List of Mars-crossing minor planets
- List of Jupiter-crossing minor planets
- List of Saturn-crossing minor planets
- List of Uranus-crossing minor planets
- List of Neptune-crossing minor planets
References edit
- ^ a b Bruce Koehn, "Minimum Orbital Intersection Distance", Lowell Observatory, retrieved online 14 May 2009, archived 15 July 2015.
- ^ Basics of Space Flight: The Solar System, p. 3, NASA Science, retrieved 14 May 2009 (from JPL site), archived 17 September 2021.
- ^ Brian G. Marsden, "Press Information Sheet:Potentially Hazardous Asteroids", Harvard-Smithsonian Center for Astrophysics, retrieved online 3 May 2009, archived 22 November 2009.
- ^ List of Prior Impacts, NEODyS, retrieved 23 September 2023.
- ^ JPL SBDB: 2014 AA (Earth impactor on 1 January 2014)
- ^ JPL SBDB: 2020 QY2 (Near-Earth asteroid roughly 2–meters in diameter)
- ^ "JPL Small-Body Database Search Engine: Group: PHA and Orbit Constraint: Earth MOID < 0.0004 (
AU )" (currently defined at an epoch of 2023-Sep-13). JPL Solar System Dynamics. Retrieved 20 September 2023. - ^ "JPL Small-Body Database: (2016 FG60)" (last observation: 2020-06-17; arc: 4.29 years). Jet Propulsion Laboratory. Archived from the original on 28 May 2019. Retrieved 23 September 2023.
- ^ JPL SBDB: 73P-BW (Short-lived comet fragment)
External links edit
- Fast Geometric Method for Calculating Accurate Minimum Orbit Intersection Distances (PDF)
- MOID for all NEOs (Near-Earth Objects) for Mercury to Jupiter (Updated Daily)
- List of the Potentially Hazardous Asteroids (PHAs)
- MBPL - Minor Body Priority List ( PHA Asteroids )
- SAEL - Small Asteroids Encounters List