- (29075) 1950 DA
Infobox Planet | discovery=yes | physical_characteristics = yes | bgcolour=#FFFFC0
name=(29075) 1950 DA
Carl A. Wirtanen
February 23, 1950
March 06, 2006(JD 2453800.5)
semimajor=254.133 Gm (1.699 AU)
perihelion=125.117 Gm (0.836 AU)
aphelion=383.148 Gm (2.561 AU)
period=808.726 d (2.21626 a)
mass=>3,000 x 109 kg
density=3.0 + g/cm³
rotation=0.0884 d (2.1216 h)
spectral_type=E or M
(29075) 1950 DA is a
near Earth asteroid. It is notable for having the highest known probabilityof impacting Earth, according to the Palermo Technical Impact Hazard Scale(although this probability remains low). For a few days in December 2004it was temporarily surpassed by 99942 Apophis(which at the time was named only by its provisional designationmp|2004 MN|4).
Discovery and name
1950 DA was first discovered on
February 23, 1950by Carl A. Wirtanenat Lick Observatory. It was observed for 17 days and then lost for half a century. An object discovered on December 31, 2000(provisionally designated mp|2000 YK|66) was later recognized as a rediscovery of 1950 DA.
The asteroid has been given the number 29075, but does not yet have a name. Wirtanen had naming rights as the original discoverer; upon his death, naming rights reverted to the IAU, which may assign a name in the future.
2001, 1950 DA made a close approach to the Earth coming to within 7.8 million km. It was studied by radar at the Goldstone and Arecibo observatories from March 3to 7, 2001.The studies showed that the asteroid has a mean diameter of 1.1–1.4 km. Optical lightcurve analysis by Lenka Sarounova and Petr Pravecshows that its rotation period is 2.1216 ± 0.0001 hours. Due to its short rotation period and high radar albedo, 1950 DA is thought to be fairly dense (more than 3 g/cm³). [ [http://echo.jpl.nasa.gov/asteroids/1950DA_goldstone/html/1950DA_planning.html 1950DA Planning] on the NASAwebsite (last accessed on October 7, 2007).]
Possible Earth impact
If 1950 DA continues on its present orbit, it will approach near to the Earth on
March 16, 2880. However, over the intervening time, its rotation will cause its orbit to change (by the Yarkovsky effect). Available radar and optical data suggest two possible pole directions [ [http://neo.jpl.nasa.gov/1950da Asteroid 1950 DA ] ] ; one trajectory misses the Earth by tens of millions of kilometers, while the other has an impact probability of 1⁄300.
The energy released by a collision with an object the size of 1950 DA would cause major effects on the
climateand biospherewhich would be devastating to human civilization. The discovery of the potential impact has heightened interest in asteroid deflection strategies.
List of noteworthy asteroids
* [http://neo.jpl.nasa.gov/1950da/ NASA Near Earth Object Program: Asteroid 1950 DA]
* [http://www.blackwell-synergy.com/links/doi/10.1046/j.1365-246X.2003.01944.x/abs/ Article on the effects of a hypothetical impact, with particular relation to a predicted megatsunami (Geophysical Journal International)]
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