View source for 2004 FU162

{{Short description|Closest known Earth approach until 2008}}
{{Use dmy dates|date=February 2018}}
{{DISPLAYTITLE:{{mp|2004 FU|162}}}}
{{Infobox planet
 | minorplanet     = yes
 | name            = {{mp|2004 FU|162}}
 | background      = #FFC2E0
 | image           = 
 | caption         = 
 | discovery_ref   = <ref name="jpldata" /><ref name="MPC-obj" />
 | discovered      = 
 | discoverer      = 
 | discovery_site  = 
 | mpc_name        = {{mp|2004 FU|162}}
 | alt_names       = <!--{{mp|2004 FU|162}}-->
 | mp_category     = [[Aten asteroid|Aten]]{{·}}[[Near-Earth object|NEO]]<ref name="jpldata" /><ref name="MPC-obj" />
 | orbit_ref       = <ref name="jpldata" />
 | epoch           = 5 April 2004 ([[Julian day|JD]] 2453100.5)
 | uncertainty     = 9
 | observation_arc = 44 minutes<ref name="MPC-obj"/>{{efn|name=arc}}<br/>(only 4 observations)
 | aphelion        = 1.1511 [[Astronomical unit|AU]]
 | perihelion      = 0.5026 AU
 | semimajor       = 0.8269 AU
 | eccentricity    = 0.3922
 | period          = 0.75 [[Julian year (astronomy)|yr]] (275 days)
 | mean_anomaly    = 262.67[[Degree (angle)|°]]
 | mean_motion     = {{Deg2DMS|1.3109|sup=ms}} / day
 | inclination     = 4.1647°
 | asc_node        = 191.25°
 | arg_peri        = 139.78°
 | moid            = 0.0001 AU
 | dimensions      = 4–12 meters {{small|(estimated)}}
 | rotation        = 
 | albedo          = 
 | spectral_type   = 
 | abs_magnitude   = 28.7<ref name="jpldata" />
}}

'''{{mp|2004 FU|162}}''' is an [[Aten asteroid|Aten]] [[near-Earth asteroid]] less than 20 meters in diameter crudely estimated to have passed roughly 6500&nbsp;km above the surface of Earth{{efn|name=surface}} on 31 March 2004.

It was only observed for 44 minutes on 31 March 2004,{{efn|name=arc}} by the [[Lincoln Near-Earth Asteroid Research]] (LINEAR) team at [[Lincoln Laboratory's Experimental Test Site]] in Socorro, New Mexico, and remains a [[lost asteroid]].<ref name="MPC-obj" /> The estimated 4 to 6 meter sized body made one of the [[List of asteroid close approaches to Earth|closest known approaches]] to Earth.

== Description ==
On 31 March 2004, around 15:35 [[UTC]], the asteroid is crudely estimated to have passed within approximately 1 [[Earth radius]] ({{Earth radius}}) or 6,400 kilometers of the surface of the Earth (or 2.02&nbsp;{{Earth radius}} from Earth's center). But due to the very short observation arc, the uncertainty in the close approach distance is a large ±15000&nbsp;km. By comparison, [[geostationary]] satellites orbit at 5.6 {{Earth radius}} and [[GPS]] satellites orbit at 3.17 {{Earth radius}} from the center of the Earth.

{{As of|2008}} this was the [[List of notable asteroids#Record-setting close approaches to Earth|third or fourth closest approach]].<!-- 1972 grazer was at 57 km, 1990 grazer was about 100km, possible 2006 grazer altitude not available --> The first observation of {{mp|2004 FU|162}} was not announced until 22 August 2004.

It was only observed four times in the space of 44 minutes and could not be followed up. Nevertheless, "the orbit is quite determinate and, given the exceptional nature of this close approach, the object is now receiving a designation".<ref name="hohm"/> No [[precovery]] images have been found.

{{mp|2004 FU|162}} is estimated to be approximately 6 meters in diameter.{{citation needed|date=April 2017}}  This means that it would burn up from [[Drag (physics)|atmospheric friction]] before striking the ground in the case of an Earth [[impact event|impact]].

On 26 March 2010, it may have come within 0.0825&nbsp;AU (12.3 million km) of Earth,<ref name=horizons /> but with an [[Uncertainty Parameter U|uncertainty parameter]] of 9,<ref name=jpldata/> the orbit is poorly determined.

Another, larger near-Earth asteroid, [[2004 FH]] passed just two weeks prior to {{mp|2004 FU|162}}.

A closer non-impacting approach to Earth was not known until {{mp|2008 TS|26}} on 9 October 2008.

== See also ==
{{Closest non-impacting asteroids to Earth}}

== Notes ==
{{notelist|refs=

{{efn|name=arc|Observation arc: (31.30799 – 31.27744) * 24 hours * 60 minutes {{=}} 43.99 minutes}}

{{efn|name=surface|The asteroid passed about 12913±15000 km from the center of Earth and Earth has a radius of 6371 km.}}

}} <!-- end of notelist -->

== References ==
<references>

<ref name="jpldata">{{cite web
  |type       = last observation: 2004-03-31; [[Observation arc|arc]]: 1 day; [[Uncertainty Parameter U|uncertainty]]: 9
  |title      = JPL Small-Body Database Browser: (2004 FU162)
  |publisher  = [[Jet Propulsion Laboratory]]
  |url        = https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2004FU162&view=OPC
  |archive-url=https://web.archive.org/web/20201128181049/http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2004FU162;cad=1
  |archive-date=2020-11-28
  |url-status=live
  |accessdate = 28 April 2017}}</ref>

<ref name="MPC-obj">{{cite web
  |title      = 2004 FU162
  |work       = Minor Planet Center
  |url        = http://www.minorplanetcenter.net/db_search/show_object?object_id=2004+FU162
  |accessdate = 28 April 2017}}</ref>

<ref name="hohm">{{cite web
  |date=22 August 2004
  |title=Closest by far
  |publisher=hohmanntransfer
  |url=http://www.hohmanntransfer.com/mn/0408/22.htm
  |accessdate=2004-08-25
  |archive-date=5 November 2016
  |archive-url=https://web.archive.org/web/20161105153448/http://www.hohmanntransfer.com/mn/0408/22.htm
  |url-status=dead
  }}</ref>

<ref name=horizons>{{cite web |last = Yeomans |first = Donald K. |url=http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=2004FU162 |title=Horizon Online Ephemeris System |publisher=California Institute of Technology, Jet Propulsion Laboratory |accessdate=2008-01-25}}</ref>

</references> <!-- end of reflist -->

== External links ==
* [http://cfa-www.harvard.edu/mpec/K04/K04Q22.html MPEC 2004-Q22] (2004 Aug. 22)
* {{JPL small body|id=3249978}}

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{{Small Solar System bodies}}
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{{DEFAULTSORT:2004 FU162}}
[[Category:Aten asteroids|#]]
[[Category:Minor planet object articles (unnumbered)]]
[[Category:Near-Earth objects in 2004|20040331]]
[[Category:Astronomical objects discovered in 2004|20040331]]
[[Category:Lost minor planets]]