2004 FH

2004 FH

Discovery
Discovered by	LINEAR
Discovery date	March 15, 2004
Designations
Alternate name(s)	none
Minor planet category	Aten asteroid, Earth-crosser asteroid Venus-crosser asteroid
Orbital characteristics
Epoch July 14, 2004 (JD 2453200.5)
Aphelion	157.651 Gm (1.054 AU)
Perihelion	87.070 Gm (0.582 AU)
Semi-major axis	122.360 Gm (0.818 AU)
Eccentricity	0.288
Orbital period	270.192 d (0.740 a)
Average orbital speed	32.237 km/s
Mean anomaly	28.042°
Inclination	0.016 62°
Longitude of ascending node	264.432°
Argument of perihelion	62.952°
Proper orbital elements
Physical characteristics
Dimensions	0.030 km
Mass	2.8×107 kg
Mean density	2 ? g/cm³
Equatorial surface gravity	8.4×10−6 m/s²
Escape velocity	16×10−6 km/s
Rotation period	? d
Albedo	0.1 ?
Temperature	~308 K
Spectral type	?
Absolute magnitude (H)	26.42

Flyby of 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

2004 FH is a near-Earth asteroid that was discovered on March 15, 2004, by the NASA-funded LINEAR asteroid survey. The object is roughly 30 metres in diameter and passed just 43,000 km (27,000 mi) above the Earth's surface on March 18, 2004, at 22:08 UTC; making it the 11th closest approach to Earth recorded as of 21 November 2008 (2008 -11-21) (see the diagram below). For comparison, geostationary satellites orbit Earth at 35,790 km.

2004 FH is an Aten family asteroid, although by some definitions it should be called a meteoroid, since it is smaller than 50 metres in diameter. Despite its relatively small size (about 30 metres), 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 ground level effect. It could also have been an Earth-grazing fireball if it had been much closer but not close enough to impact.

The asteroid will not make another close approach to Earth until 2044 when it will be no closer than 1.4 Gm (1.4 million kilometres). 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.

Trajectory of 2004 FH in the Earth-Moon system

See also

• Near-Earth object
• List of notable asteroids

References

1. Chesley, Steven R; Chodas, Paul W. Recently Discovered Near-Earth Asteroid Makes Record-breaking Approach to Earth. Pasadena, California (USA): NASA Near Earth Object Program Office. March 17, 2004.

External links

• MPEC 2004-F24
• Images of 2004 FH
• Official press release by NASA
• Asteroid Scare Prompts NASA to Formalize Response by Robert Roy Britt
• Minor Planet Center: Closest Approaches to the Earth by Minor Planets