Diagram showing different asteroid paths. The yellow band marks the Earth's orbit; the red line marks the asteroid's path.
Outer-grazer(†): middle, bottom
Crosser: right, bottom

Close approach trajectory of 2004 FH in the Earth–Moon system

Flyby of the near-Earth asteroid 2004 FH in March 2004. The other object that flashes by is an artificial satellite. Images were by Stefano Sposetti and composite by Raoul Behrend of Geneva Observatory

An Earth-crosser is a near-Earth asteroid whose orbit crosses that of Earth as observed from the ecliptic pole of Earth's orbit.^[1] The known numbered Earth-crossers are listed here. Those Earth-crossers whose semi-major axes are smaller than Earth's are Aten asteroids; the remaining ones are Apollo asteroids. See also the Amor asteroids.

An asteroid with an Earth-crossing orbit is not necessarily in danger of colliding with the Earth. The orbit of an Earth-crossing asteroid may not even intersect with the orbit of the Earth. This apparent contradiction arises because many asteroids have highly inclined orbits, so although they may have a perihelion less than that of the Earth, their paths can never cross. An asteroid for which there is some possibility of a collision with the Earth at a future date and which is above a certain size is classified as a Potentially Hazardous Asteroid (PHA). Specifically, an asteroid is a PHA if its Earth Minimum Orbital Intersection Distance (MOID) is <0.05 AU and its absolute magnitude is 22 or less.^[2] The concept of PHA is intended to replace the now abandoned strict definition of ECA (Earth-crossing asteroid) which existed for a few years. Determining if an asteroid was an ECA required calculation of its orbits millennia into the future, including planetary gravitational peturbations, to assess whether a collision with Earth was possible and this has proved to be impractical.^[3]

Having a small MOID is not a guarantee of a collision. On the other hand, small gravitational peturbations of the asteroid around its orbit from planets that it passes can significantly alter its path. For instance, 99942 Apophis will approach the Earth so closely in 2029 that it will get under the orbit of the Earth's geostationary satellites. The Earth will change the trajectory of Apophis and the result may be an even closer approach in the future, possibly 2036. It is not currently possible to accurately predict the path of Apophis subsequent to the 2029 encounter because its present orbit is not yet known to a sufficiently high precision — very small differences prior to the planetary encounter can produce large differences in orbit after the encounter.^[4]

Of the Earth-crossing asteroids, 3753 Cruithne is notable for having an orbit that has the same period as Earth's.

List [edit]

Notes: † outer-grazer

See also [edit]

• Earth-grazing fireball
• Asteroid deflection strategies
• List of Mercury-crossing minor planets
• List of Venus-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]

External links [edit]

• Very Close Approaches (<0.01 A.U.) of PHAs to Earth 1800–2200
• Upcoming Close Approaches (<0.10 A.U.) of Near-Earth Objects to Earth
• Table of next close approaches to the Earth
• Small Asteroids Encounter List
• Minor Body Priority List
• IAU-MPC Close Approaches to the Earth within 0.2 AU

v t e Impact cratering on Earth Geology Lists Worldwide Africa Antarctica Asia Australia Europe North America South America by country Confirmed ≥20 km diameter Acraman Amelia Creek Araguainha Beaverhead Boltysh Carswell Charlevoix Chesapeake Bay Chicxulub Clearwater East & West Gosses Bluff Haughton Kamensk Kara Karakul Keurusselkä Lappajärvi Logancha Manicouagan Manson Mistastin Mjølnir Montagnais Morokweng Nördlinger Ries Obolon' Popigai Presqu'île Puchezh-Katunki Rochechouart Saint Martin Shoemaker Siljan Ring Slate Islands Steen River Strangways Sudbury Tookoonooka Vredefort Woodleigh Yarrabubba Topics Alvarez hypothesis Breccia Coesite Complex crater Cryptoexplosion Ejecta blanket Impact crater Impact structure Impactite Cretaceous–Paleogene boundary Late Heavy Bombardment lechatelierite Meteorite Moldavite Ordovician meteor event Planar deformation features Shatter cone Shock metamorphism Shocked quartz Stishovite Suevite Tektite Research Baldwin, Ralph Belknap Barringer, Daniel Barringer Medal Chao, Edward C T Dietz, Robert S Earth Impact Database Hartmann, William K Impact Field Studies Group Lunar and Planetary Institute Melosh, H Jay Ryder, Graham Schultz, Peter H Shoemaker, Eugene Traces of Catastrophe book Astronomy Observation Asteroid Catalina Sky Survey Close approaches Earth-crosser asteroid Impact event LINEAR LONEOS Meteoroid Meteoritical Society NASA NEAT Near-Earth Object (NEO) NEOSSat Orbit@home Palermo Scale Pan-STARRS Planetary science Potentially hazardous object Sentry Spacewatch Torino Scale WISE Defense Asteroid impact avoidance B612 Foundation Gravity tractor Ion Beam Shepherd Japan Spaceguard Association NEOShield Spaceguard The Spaceguard Foundation Potential threats 1950 DA 1994 WR12 1999 RQ36 2002 MN 99942 Apophis 2004 VD17 2007 VK184 2011 BT15

We're sorry, but there's no news about "List of Earth-crossing minor planets" right now.