View source for 2004 FH

{{Use dmy dates|date=February 2018}}
{{Infobox planet
| minorplanet = yes
| name = 2004 FH
| background = #FFC2E0
| image = Asteroid 2004 FH.gif
| image_scale = 
| caption = Flyby of asteroid {{mp|2004 FH}} {{efn|name=image-description-extended}}, the object that flashes by is a man-made satellite.
| discovery_ref = <ref name="jpldata" /><ref name="MPC-object" />
| discoverer = [[Lincoln Near-Earth Asteroid Research|LINEAR]]
| discovery_site = [[Lincoln Laboratory's Experimental Test Site|Lincoln Lab's ETS]]
| discovered = 16 March 2004
| mpc_name = 2004 FH
| alt_names = 2004 FH
| pronounced = 
| named_after = 
| mp_category = [[Near-Earth object|NEO]]{{·}}[[Aten asteroid|Aten]]<ref name="jpldata" />
| orbit_ref = <ref name="jpldata" />
| epoch = 4 September 2017 ([[Julian day|JD]] 2458000.5)
| uncertainty = 5
| observation_arc = 3 days
| aphelion = 1.0545 [[Astronomical unit|AU]]
| perihelion = 0.5816 AU
| semimajor = 0.8180 AU
| eccentricity = 0.2891
| period = 0.74 [[Julian year (astronomy)|yr]] (270 days)
| mean_anomaly = 302.96[[Degree (angle)|°]]
| mean_motion = {{Deg2DMS|1.3321|sup=ms}} / day
| inclination = 0.0210°
| asc_node = 290.98°
| arg_peri = 36.622°
| moid = 0.00002265 AU<br />{{nowrap|0.0088 [[Lunar distance (astronomy)|LD]]{{·}}(3390 km)}}
| dimensions = 24 m {{small|(calculated)}}<ref name="lcdb" /><br />30 m {{small|(estimate)}}<ref name="news142"/>
| mass = <!-- 2.8{{e|7}} kg source?-->
| rotation = {{Convert|0.0504|h|min|abbr=on|lk=on}}<ref name="lcdb" />
| albedo = 0.20 {{small|(assumed)}}<ref name="lcdb" />
| spectral_type = [[S-type asteroid|S]] {{small|(assumed)}}<ref name="lcdb" />
| abs_magnitude = 25.7<ref name="jpldata" />
}}

'''2004 FH''' is a micro-[[asteroid]] and [[near-Earth object]] of the [[Aten asteroid|Aten group]], approximately 30 meters in diameter, that passed just {{convert|43,000|km|mi|abbr=on}} above the [[Earth]]'s surface on 18 March 2004, at 22:08 [[Coordinated Universal Time|UTC]]. It was the [[List of asteroid close approaches to Earth|11th closest approach to Earth]] recorded {{As of|2008|11|21|lc=on}}.{{efn|name=record-definitions}} The asteroid was first observed on 16 March 2004, by astronomers of the [[Lincoln Near-Earth Asteroid Research]] at the [[Lincoln Laboratory's Experimental Test Site]] near Socorro, New Mexico.<ref name="MPC-object" />

== Orbit and classification ==
[[File:2004fs56992main 2004.jpg|thumb|left|Trajectory of {{mp|2004 FH}} in the Earth–Moon system]]

{{mp|2004 FH}} is an [[Aten asteroid]]. It passed 43,000&nbsp;km from the Earth on 18 March 2004. For comparison, [[geostationary satellite]]s orbit Earth at 35,790 kilometers. Despite its small size, it is still the fourth largest asteroid detected coming closer to the Earth than the Moon.

Had this object hit Earth, it would probably have detonated high in the [[Earth's atmosphere|atmosphere]]. It might have produced a blast measured in hundreds of kilotons of [[Trinitrotoluene|TNT]], but may not have produced any effect on the ground. It could also have been an [[Earth-grazing fireball]] if it had been much closer but not close enough to impact.{{citation needed|date=November 2017}}<!--infobox: MASS= 2.8{{e|7}} kg source?-->

On 17 March 2044 the asteroid will pass no closer than {{convert|0.0116|AU|km mi|abbr=on|lk=off}} from the Earth.<ref name=jpl-close/> {{mp|2004 FH}} also has the distinction of having the lowest [[inclination]] of any known near-Earth asteroids.

Two weeks later another asteroid approached even closer, {{mpl|2004 FU|162}}, which was smaller; and a few years later {{mpl|2009 DD|45}}, which was closer in size, passed by at similar distance.

== Physical characteristics ==

{{mp|2004 FH}} is an assumed stony [[S-type asteroid]].<ref name="lcdb" />

=== Rotation period ===

In March 2004, two rotational [[lightcurve]]s of {{mp|2004 FH}} were obtained from photometric observations by astronomers [[Petr Pravec]], [[Stefano Sposetti]] and [[Raoul Behrend]]. Lightcurve analysis gave a [[rotation period]] of 0.0504 hours (3.02 minutes) with a brightness amplitude of 1.16 and 0.75 [[Magnitude (astronomy)|magnitude]], respectively ({{small|[[LCDB quality code|U=3/2+]]}}).<ref name="lcdb" /><ref name="geneva-obs" />

This makes this object a [[List of fast rotators (minor planets)|fast rotator]], currently among the [[List of fast rotators (minor planets)#Periods 0.05–0.1 hour|Top 100]] known to exist. The photometric observations also revealed, that {{mp|2004 FH}} is a [[List of tumblers (small Solar System bodies)|tumbler]] with a non-principal axis rotation.<ref name="lcdb" />

=== Diameter and albedo ===

has been estimated to measure approximately 30 meters (100 feet) in diameter.<ref name="news142"/> The ''Collaborative Asteroid Lightcurve Link'' assumes a standard [[astronomical albedo|albedo]] for stony asteroids of 0.20 and calculates a diameter of 24 meters based on an [[absolute magnitude]] of 25.7.<ref name="lcdb" />

== Notes ==
{{notelist|refs=

{{efn|name=image-description-extended|1=Flyby of asteroid 2004 FH (center dot being followed by the sequence). The other object that flashes by is an artificial [[satellite]]. Images were taken by [[Stefano Sposetti]] and composited by [[Raoul Behrend]] of [[Geneva Observatory]].}}

{{efn|name=record-definitions|1=Rankings depend on definitions of meteoroid and approach. The 2-10 m 1972 grazer was at 57 km, the 44 kg 1990 grazer was about 100 km, possible 2006 grazer size and altitude not available. ''See [[List of asteroid close approaches to Earth]]''.}}

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

== References ==
{{reflist|30em|refs=

<ref name="jpldata">{{cite web
  |type       = 2004-03-19 last obs.
  |title      = JPL Small-Body Database Browser: (2004 FH)
  |url        = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=3177202
  |publisher  = [[Jet Propulsion Laboratory]]
  |accessdate = 23 November 2017}}</ref>

<ref name=jpl-close>{{cite web
  |type=last observation: 2004-03-19; [[Observation arc|arc]]: 3 days; [[Uncertainty Parameter U|uncertainty]]: 3
  |title=JPL Close-Approach Data: (2004 FH)
  |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2004FH;cad=1#cad
  |accessdate=23 March 2016}}</ref>

<ref name="news142">{{cite web
  |date=March 17, 2004
  |title=Recently Discovered Near-Earth Asteroid Makes Record-breaking Approach to Earth 
  |publisher=NASA's Near Earth Object Program Office
  |author=Steven R. Chesley
  |author2=Paul W. Chodas
  |url=https://cneos.jpl.nasa.gov/news/news142.html
  |accessdate = 23 November 2017}}</ref>

<ref name="MPC-object">{{cite web
  |title      = 2004 FH
  |work       = Minor Planet Center
  |url        = http://www.minorplanetcenter.net/db_search/show_object?object_id=2004+FH
  |accessdate = 23 November 2017}}</ref>

<ref name="geneva-obs">{{cite web
  |title      = Asteroids and comets rotation curves – (2004 FH)
  |last       = Behrend |first = Raoul
  |publisher  = [[Geneva Observatory]]
  |url        = http://obswww.unige.ch/~behrend/page5cou.html#04f00h
  |accessdate = 23 November 2017}}</ref>

<ref name="lcdb">{{cite web
  |title      = LCDB Data for (2004) 
  |publisher  = Asteroid Lightcurve Database (LCDB)
  |url        = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=0%7C2004+FH
  |accessdate = 23 November 2017}}</ref>

}} <!-- end of reflist -->

== External links ==
{{Commons}}
* [http://www.minorplanetcenter.org/mpec/K04/K04F24.html MPEC 2004-F24]
* [http://www.klet.org/klenot//html/2004fh.html Images of 2004 FH] at Klet
* [http://www.minorplanet.info/PHP/lcdbsummaryquery.php Asteroid Lightcurve Database (LCDB)], query form ([http://www.minorplanet.info/lightcurvedatabase.html info] {{Webarchive|url=https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html |date=16 December 2017 }})
* [http://obswww.unige.ch/~behrend/page_cou.html Asteroids and comets rotation curves, CdR] – Observatoire de Genève, Raoul Behrend
* {{NeoDys|2004+FH}}
* {{ESA-SSA|2004FH}}
* {{JPL small body}}

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{{DEFAULTSORT:2004 FH}}
[[Category:Aten asteroids|#]]
[[Category:Minor planet object articles (unnumbered)]]
[[Category:Fast rotating minor planets|#]]
[[Category:Near-Earth objects in 2004|20040318]]
[[Category:Astronomical objects discovered in 2004|20040316]]