2004 FH

2004 FH is a micro-asteroid and near-Earth object of the Aten group, approximately 30 meters in diameter, that passed just 43,000 km (27,000 mi) above the Earth's surface on 18 March 2004, at 22:08 UTC. It was the 11th closest approach to Earth recorded as of 21 November 2008.[lower-alpha 2] 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.[2]

2004 FH
Flyby of asteroid 2004 FH [lower-alpha 1]
Discovery [1][2]
Discovered byLINEAR
Discovery siteLincoln Lab's ETS
Discovery date16 March 2004
Designations
2004 FH
2004 FH
NEO · Aten [1]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 5
Observation arc3 days
Aphelion1.0545 AU
Perihelion0.5816 AU
0.8180 AU
Eccentricity0.2891
0.74 yr (270 days)
302.96°
1° 19m 55.56s / day
Inclination0.0210°
290.98°
36.622°
Earth MOID0.00002265 AU
0.0088 LD · (3390 km)
Physical characteristics
Dimensions24 m (calculated)[3]
30 m (estimate)[4]
0.0504 h (3.02 min)[3]
0.20 (assumed)[3]
S (assumed)[3]
25.7[1]

    Orbit and classification
    Trajectory of 2004 FH in the Earth–Moon system

    2004 FH is an Aten asteroid. It passed 43,000 km from the Earth on 18 March 2004. For comparison, geostationary satellites 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 atmosphere. It might have produced a blast measured in hundreds of kilotons of 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.

    On 17 March 2044 the asteroid will pass no closer than 0.0116 AU (1,740,000 km; 1,080,000 mi) from the Earth.[5] 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, 2004 FU162, which was smaller, and a few years later 2009 DD45, which was closer in size passed by at similar distance.

    Physical characteristics

    2004 FH is an assumed stony S-type asteroid.[3]

    Rotation period

    In March 2004, two rotational lightcurves of 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, respectively (U=3/2+).[3][6]

    This makes this object a fast rotator, currently among the Top 100 known to exist. The photometric observations also revealed, that 2004 FH is a tumbler with a non-principal axis rotation.[3]

    Diameter and albedo

    has been estimated to measure approximately 30 meters (100 feet) in diameter.[4] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 24 meters based on an absolute magnitude of 25.7.[3]

    Notes
    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.
    2. 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.

    References
    1. "JPL Small-Body Database Browser: (2004 FH)" (2004-03-19 last obs.). Jet Propulsion Laboratory. Retrieved 23 November 2017.
    2. "2004 FH". Minor Planet Center. Retrieved 23 November 2017.
    3. "LCDB Data for (2004)". Asteroid Lightcurve Database (LCDB). Retrieved 23 November 2017.
    4. Steven R. Chesley; Paul W. Chodas (17 March 2004). "Recently Discovered Near-Earth Asteroid Makes Record-breaking Approach to Earth". NASA's Near Earth Object Program Office. Retrieved 23 November 2017.
    5. "JPL Close-Approach Data: (2004 FH)" (last observation: 2004-03-19; arc: 3 days; uncertainty: 3). Retrieved 23 March 2016.
    6. Behrend, Raoul. "Asteroids and comets rotation curves – (2004 FH)". Geneva Observatory. Retrieved 23 November 2017.

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