(29075) 1950 DA

Discovery and nomenclature

was first discovered on 23 February 1950 by Carl A. Wirtanen at Lick Observatory. Just two hours later it was recognized as .

Observations

On 5 March 2001, made a close approach to Earth at a distance of 0.05207 AU. It was studied by radar at the Goldstone and Arecibo observatories from March 3 to 7, 2001.

The studies showed that the asteroid has a mean diameter of 1.1 km, assuming that is a retrograde rotator. Optical lightcurve analysis by Lenka Šarounová and Petr Pravec shows that its rotation period is hours. Due to its short rotation period and high radar albedo, is thought to be fairly dense (more than 3.5 g/cm3, assuming that it has no internal strength) and likely composed of nickel–iron. In August 2014, scientists from the University of Tennessee determined that ** is a rubble pile rotating faster than the breakup limit for its density, implying the asteroid is held together by van der Waals forces rather than gravity.

made distant approaches to Earth on 20 May 2012, 5 February 2021 and 5 February 2023. However, at these times it was a quarter to half an AU away from Earth, preventing more useful astrometrics and timing that occurs when an object is closer to Earth. The next close approach that presents a good opportunity to observe the asteroid will be on 2 March 2032, when it will be 0.076 AU from Earth. The following table lists the approaches closer than 0.1 AU until the year 2500. By 2136 the close approach solutions are becoming notably more divergent.

Possible Earth impact

has one of the best-determined asteroid orbital solutions. This is due to a combination of:

• an orbit moderately inclined (12 degrees) to the ecliptic plane (reducing in-plane perturbations);
• high-precision radar astrometry, which provides its distance and is complementary to the measurements of angular positions;
• a 74-year observation arc;
• an uncertainty region controlled by resonance.

Main-belt asteroid 78 Diana (~125 km in diameter) will pass about 0.003 AU from on 5 August 2150. At that distance and size, Diana will perturb enough so that the change in trajectory is notable by 2880 (730 years later). In addition, over the intervening time, 's rotation will cause its orbit to slightly change as a result of the Yarkovsky effect. If continues on its present orbit, it may approach Earth on 16 March 2880, though the mean trajectory passes many millions of kilometres from Earth, so does not have a significant chance of impacting Earth. , according to the latest solution dated 11 September 2025, the probability of an impact in 2880 is 1 in 2,600 (0.038%).

The energy released by a collision with an object the size of would cause major effects on the climate and biosphere, which would be devastating to human civilization. The discovery of the potential impact heightened interest in asteroid deflection strategies.

Notes

References

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References

1. (29 March 2022). "Impact threat analysis update completed for 1950 DA". European Space Agency.
2. (4 January 2001). "MPEC 2001-A22 : 2000 YK66". Minor Planet Center.
3. (4 January 2001). "MPEC 2001-A26 : 1950 DA = 2000 YK66". Minor Planet Center.
4. "Close-approach results". JPL Horizons.
5. (January 2015). "Star catalog position and proper motion corrections in asteroid astrometry". Icarus.
6. "Sentry: Earth Impact Monitoring".
7. (1 June 2024). "Asteroid Orbit Determination Using Gaia FPR: Statistical Analysis". The Astronomical Journal.