163693 Atira

Infobox Planet | discovery=yes | physical_characteristics = yes | bgcolour=#FFFFC0
name=Atira
discoverer=M. Blythe, F. Shelly,
M. Bezpalko, R. Huber,
L. Manguso, S. Adams,
D. Torres, T. Brothers,
S. Partridge / LINEAR
discovered=February 11, 2003
alt_names="none"
mp_category=Aten, Apohele
Venus-crosser
epoch=October 22, 2004 (JD 2453300.5)
semimajor=110.865 Gm (0.741 AU)
perihelion=75.149 Gm (0.502 AU)
aphelion=146.580 Gm (0.980 AU)
eccentricity=0.322
period=233.023 d (0.64 a)
inclination=25.618°
asc_node=103.952°
arg_peri=252.914°
mean_anomaly=20.298°
avg_speed=33.68 km/s
dimensions=~2.0 km
mass=1.0×10¹² kg
density=2.0? g/cm³
surface_grav=0.0003 m/s²
escape_velocity=0.0005 km/s
rotation=? d
spectral_type=?
abs_magnitude=16.43
albedo=0.10
single_temperature=~323 KDiscovered February 11, 2003, by the Lincoln Near-Earth Asteroid Research project's station at Socorro, New Mexico, (163693) Atira (previously named mp|2003 CP|20), was the first asteroid known to have an orbit entirely within that of Earth. Together with mpl|2004 JG|6, which has an even smaller orbit, it forms a subclass of Aten asteroids, known as Apoheles. Atira takes slightly over 233 days to orbit the Sun. It is a Venus-crosser asteroid, but does not get as close to the Sun as Mercury. With a diameter of about 2 km, it is the larger of the two known Apoheles and is one of the larger Aten asteroids.

External links

* [http://earn.dlr.de/nea/163693.htm Discovery Circumstances]
* [http://newton.dm.unipi.it/cgi-bin/neodys/neoibo?objects:Atira;main Orbital Information]
* [http://www.klet.org/html/2003cp20.html Photo]