Editing (29075) 1950 DA (section)

== Observations ==
{{multiple image
 |direction = vertical
 |align     = left
 |width     = 215
 |image1    = 1950 DA (color).png
 |image2    = 1950 DA radar movie.gif
 |caption1  = Asteroid ''{{mp|1950 DA}}'', [[Arecibo Observatory]] radar image (coloured version)
 |caption2  = Arecibo radar movie of {{mp|1950 DA}} obtained during 48 minutes (37% of a rotation) on 4 March 2001
}}

On 5 March 2001, {{mp|1950 DA}} made a close approach to Earth at a distance of {{convert|0.05207|AU|e6km e6mi LD|abbr=unit|lk=on}}.<ref name=jpl-close/> It was studied by radar at the [[Goldstone Observatory|Goldstone]] and [[Arecibo Observatory|Arecibo]] observatories from March 3 to 7, 2001.<ref name="Giorgini-2002" />

The studies showed that the asteroid has a [[mean diameter]] of 1.1&nbsp;km, assuming that {{mp|1950 DA}} is a retrograde rotator.<ref name="Farnocchia-2014" /> Optical [[lightcurve]] analysis by [[Lenka Šarounová]] and [[Petr Pravec]] shows that its rotation period is {{val|2.1216|0.0001}} hours. Due to its short rotation period and high radar [[albedo]], {{mp|1950 DA}} is thought to be fairly dense (more than 3.5&nbsp;g/cm<sup>3</sup>, assuming that it has no internal strength) and likely composed of [[nickel]]–[[iron]].<ref name="Busch-2007b" /> In August 2014, scientists from the [[University of Tennessee]] determined that ''{{mp|1950 DA}}'' is a [[rubble pile]] rotating faster than the breakup limit for its density, implying the asteroid is held together by [[van der Waals force]]s rather than gravity.<ref name="Rozitis-2014" /><ref name="tntoday" />

{{mp|1950 DA}} made distant approaches to Earth on 20 May 2012, 5 February 2021 and 5 February 2023.<ref name=jpl-close/> However, at these times it was a quarter to half an AU away from Earth, preventing more useful [[astrometry|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 {{convert|0.076|AU|e6km|abbr=unit|lk=off}} from Earth. The following table lists the approaches closer than 0.1&nbsp;AU until the year 2500.<ref name="jpl-close-hor"/> By 2136 the close approach solutions are becoming notably more divergent.{{citation needed|date=June 2024}}

{| class="wikitable sortable" style="font-size: 0.9em;"
|+Position uncertainty and increasing divergence<ref name="jpl-close-hor">{{Cite web|url=https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND=%2729075%27&EPHEM_TYPE=%27APPROACH%27&CA_TABLE_TYPE=%27EXTENDED%27&CALIM_SB=%270.10%27&START_TIME=%272020-01-01%27&STOP_TIME=%272500-01-01%27|title=Close-approach results|work=JPL Horizons|access-date=7 December 2024}} Soln.date: 2024-Dec-05 05:58:05</ref>
! Date
! [[JPL SBDB]]<br />[[Curve fitting|nominal]] geocentric<br />distance ([[astronomical unit|AU]])
! uncertainty<br />region<br/>([[68–95–99.7 rule|1-sigma]])
|-
| 2 March 2032 ||{{Convert|0.075752|AU|km|abbr=unit}} || ±10&nbsp;km
|-
|19 March 2074 ||{{Convert|0.095459|AU|km|abbr=unit}} || ±30&nbsp;km
|-
|10 March 2105 ||{{Convert|0.036316|AU|km|abbr=unit}} || ±43&nbsp;km
|-
|11 March 2136 ||{{Convert|0.042596|AU|km|abbr=unit}} || ±387&nbsp;km
|-
| 8 March 2187 ||{{Convert|0.035224|AU|km|abbr=unit}} || ±1717&nbsp;km
|-
|20 March 2218 ||{{Convert|0.084849|AU|km|abbr=unit}} || ±8712&nbsp;km
|-
|18 March 2373 ||{{Convert|0.058991|AU|km|abbr=unit}} || ±2508&nbsp;km
|-
| 6 March 2455 ||{{Convert|0.087706|AU|km|abbr=unit}} || ±1650&nbsp;km
|}
{| class="wikitable sortable" style="font-size: 0.9em;"
|+Impact probability at different times

! Date
! JPL Solution
! Impact probability
|-
| 5 April 2002 ||<ref name="Giorgini-2002"/> 
|| 1/306
|-
|7 December 2015 ||<ref>{{cite journal |last1=Farnocchia |first1=D. |last2=Chesley |first2=S.R. |last3=Chamberlin |first3=A.B. |last4=Tholen |first4=D.J. |title=Star catalog position and proper motion corrections in asteroid astrometry |journal=Icarus |date=January 2015 |volume=245 |pages=94–111 |doi=10.1016/j.icarus.2014.07.033 |arxiv=1407.8317 |bibcode=2015Icar..245...94F }}</ref> || 1/8300
|-
|29 March 2022 ||<ref>{{cite web | url=https://cneos.jpl.nasa.gov/sentry/notes.html | title=Sentry: Earth Impact Monitoring }}</ref> || 1/34000
|-
|18 June 2024 ||<ref>{{cite journal |last1=Fuentes-Muñoz |first1=Oscar |last2=Farnocchia |first2=Davide |last3=Naidu |first3=Shantanu P. |last4=Park |first4=Ryan S. |title=Asteroid Orbit Determination Using Gaia FPR: Statistical Analysis |journal=The Astronomical Journal |date=1 June 2024 |volume=167 |issue=6 |pages=290 |doi=10.3847/1538-3881/ad4291 |doi-access=free |bibcode=2024AJ....167..290F }}</ref> || 1/2600

|-
|23 January 2025 ||JPL276|| 1/2600
|}