List of Earth-crossing asteroids

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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 Orbites definition.png
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 Trajectory of 2004 FH in the Earth-Moon system.svg
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 Asteroid 2004 FH.gif
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.)

Contents

An asteroid with an Earth-crossing orbit is not necessarily in danger of colliding with Earth. The orbit of an Earth-crossing asteroid may not even intersect with that of Earth. This apparent contradiction arises because many asteroids have highly inclined orbits, so although they may have a perihelion less than that of Earth, their paths can never cross. An asteroid for which there is some possibility of a collision with 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 brighter. [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 perturbations, 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 perturbations of the asteroid around its orbit from planets that it passes can significantly alter its path. For instance, 99942 Apophis will approach Earth so closely in 2029 that it will get under the orbit of the Earth's geostationary satellites. [4]

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

List

Notes: † outer-grazer

See also

Related Research Articles

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Piero Sicoli is an Italian astronomer and discoverer of minor planets, observing at the Italian Sormano Astronomical Observatory. As the observatory's coordinator, he is responsible for close encounters computation of near-Earth objects (NEOs), orbit computations, and identification of asteroids. The Observatory's focus is the examination and tracking of NEOs in Solar System.

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<span class="nowrap">(33342) 1998 WT<sub>24</sub></span> Sub-kilometer asteroid

(33342) 1998 WT24 is a bright, sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid (PHA) of the Aten group, located in Venus's zone of influence that has frequent close encounters with Mercury, Venus, and Earth. It made a close approach to Earth on 11 December 2015, passing at a distance of about 4.2 million kilometers (2.6 million miles, 11 lunar distances) and reaching about apparent magnitude 11.

99942 Apophis (provisional designation 2004 MN4) is a near-Earth asteroid and a potentially hazardous object with a diameter of 370 metres (1,210 feet) that caused a brief period of concern in December 2004 when initial observations indicated a probability up to 2.7% that it would hit Earth on April 13, 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth in 2029. Until 2006, a small possibility nevertheless remained that, during its 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole of no more than about 800 kilometres (500 mi) in diameter, which would have set up a future impact exactly seven years later on April 13, 2036. This possibility kept it at Level 1 on the Torino impact hazard scale until August 2006, when the probability that Apophis would pass through the keyhole was determined to be very small and Apophis's rating on the Torino scale was lowered to zero. By 2008, the keyhole had been determined to be less than 1 km wide. During the short time when it had been of greatest concern, Apophis set the record for highest rating ever on the Torino scale, reaching level 4 on December 27, 2004.

(179806) 2002 TD66 (also written 2002 TD66) is a sub-kilometer asteroid, classified as near-Earth object of the Apollo group. It was discovered on 5 October 2002, by the LINEAR project at Lincoln Laboratory's ETS in Socorro, New Mexico. It was announced on 7 October 2002 and appeared later that day on the JPL current risk page.

<span class="mw-page-title-main">Potentially hazardous object</span> Hazardous near-Earth asteroid or comet

A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and which is large enough to cause significant regional damage in the event of impact. They are conventionally defined as having a minimum orbit intersection distance with Earth of less than 0.05 astronomical units and an absolute magnitude of 22 or brighter, the latter of which roughly corresponds to a size larger than 140 meters. More than 99% of the known potentially hazardous objects are no impact threat over the next 100 years. As of September 2022, just 17 of the known potentially hazardous objects listed on the Sentry Risk Table could not be excluded as potential threats over the next hundred years. Over hundreds if not thousands of years though, the orbits of some "potentially hazardous" asteroids can evolve to live up to their namesake.

<span class="mw-page-title-main">Minimum orbit intersection distance</span> Measure of close approach or collision risk in astronomy

Minimum orbit intersection distance (MOID) is a measure used in astronomy to assess potential close approaches and collision risks between astronomical objects. 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.

(85640) 1998 OX4 (provisional designation 1998 OX4) is a sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group.

2003 BR47 is a sub-kilometer asteroid classified as near-Earth object and potentially hazardous asteroid of the Apollo group. It was discovered on 31 January 2003 by the LINEAR program. As of 19 March 2013, its orbit is based on 170 observations spanning a data-arc of 939 days.

2013 ND15 (also written 2013 ND15) is an asteroid that is a temporary trojan of Venus, the first known Venus trojan.

(456938) 2007 YV56, provisional designation 2007 YV56, is a sub-kilometer asteroid on an eccentric orbit, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 190–360 meters (620–1,200 ft) in diameter. It was discovered on 31 December 2007, by astronomers of the Catalina Sky Survey conducted at the Catalina Station in Arizona, United States.

2011 GA is a small asteroid that is a Near-Earth object and an Apollo asteroid.

(549948) 2011 WL2 is a sub-kilometer asteroid, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group. It was discovered on 16 November 2011, by astronomers with the LINEAR at the Lincoln Laboratory ETS near Socorro, New Mexico, in the United States.

(415713) 1998 XX2 is a sub-kilometer asteroid, classified as a near-Earth object and potentially hazardous asteroid of the Aten group. It was discovered 8 December 1998, by the Lincoln Near-Earth Asteroid Research at Lincoln Laboratory's Experimental Test Site, and was found to have frequent approaches to the Earth, Venus, and Mercury.

<span class="nowrap">(52768) 1998 OR<sub>2</sub></span> Asteroid

(52768) 1998 OR2 (provisional designation 1998 OR2) is an asteroid on an eccentric orbit, classified as a near-Earth object and potentially hazardous asteroid of the Amor group, with a diameter of 2 kilometers (1.2 mi). It was discovered on 24 July 1998, by astronomers of the Near-Earth Asteroid Tracking (NEAT) program at the Haleakala Observatory, Hawaii. It is one of the brightest and therefore largest potentially hazardous asteroids known to exist. With an observation arc of 35 years, the asteroid has a well-determined orbit, and its trajectory is well known through the year 2197. The asteroid's orbit is only potentially hazardous on a time scale of thousands of years.

(85182) 1991 AQ is a stony asteroid on a highly eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 1.1 kilometers in diameter. It was discovered on 14 January 1991, by American astronomer Eleanor Helin at the Palomar Observatory in California. Based on its brightness variation of 0.69 magnitude, this Q-type asteroid is likely elongated. It belongs to the small group of potentially hazardous asteroids larger than one kilometer.

2019 PG1 is a sub-kilometer near-Earth object and potentially hazardous asteroid of the Apollo class, discovered by Pan-STARRS on 8 August 2019, two weeks after it passed Earth at 62 LD. With an observation arc of 103 days, Earth approach dates become divergent by 2042 as the date of closest approach in 2042 has an uncertainty of ±3 days.

References

  1. ↑ Report of the Task Force on potentially hazardous Near Earth Objects, p49, Department of Trade and Industry (UK), September 2000, Pub 4990/5k/9/00/NP.URN00/1041, retrieved online Archived 7 March 2009 at the Wayback Machine , 16 May 2009.
  2. ↑ "Near Earth Object Program", National Aeronautics and Space Administration, retrieved online 3 May 2009.
  3. ↑ Brian G. Marsden, "Press Information Sheet:Potentially Hazardous Asteroids", Harvard-Smithsonian Center for Astrophysics, retrieved online 3 May 2009.
  4. ↑ Dr. Tony Phillips, "Friday the 13th, 2029", Science@NASA, retrieved online Archived 24 March 2010 at the Wayback Machine May 3, 2009.
  5. ↑ MPEC 2020-Q51 : 2020 QG, Minor Planet Center, https://www.minorplanetcenter.net/mpec/K20/K20Q51.html, 17 August 2020, accessed 17 August 2020.
  6. ↑ Newly-discovered asteroid ZTF0DxQ passed less than 1/4 Earth diameter yesterday, making it the closest-known flyby that didn't hit our planet., Tony Dunn, 17 August 2020.
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