Jump to content
 







Main menu
    


Navigation  


●Main page
 ●Contents
 ●Current events
 ●Random article
 ●About Wikipedia
 ●Contact us
 ●Donate
  



Contribute  


●Help
 ●Learn to edit
 ●Community portal
 ●Recent changes
 ●Upload file
  







Search  

































●Create account

●Log in
 









●Create account
 ● Log in
  



Pages for logged out editors learn more  


●Contributions
 ●Talk
  


















Contents

   



(Top)
  


1 Notes  




2 References  




3 External links  













2021 UA1






●日本語
 ●Українська
  
Edit links
  








●Article
 ●Talk
  
















●Read
 ●Edit
 ●View history
  







Tools
    


Actions  


●Read
 ●Edit
 ●View history
  



General  


●What links here
 ●Related changes
 ●Upload file
 ●Special pages
 ●Permanent link
 ●Page information
 ●Cite this page
 ●Get shortened URL
 ●Download QR code
 ●Wikidata item
  



Print/export  


●Download as PDF
 ●Printable version
  















Appearance
    

 





From Wikipedia, the free encyclopedia
  

2021 UA1
Orbit of 2021 UA1
Discovery[1]
Discovered byCatalina Sky Survey
Discovery date25 October 2021
Designations

MPC designation

2021 UA1

Minor planet category

  • Aten (pre-flyby)
  • Apollo (post-flyby)
  • risk listed[2]
    • Orbital characteristics[3]
    Epoch 2021-Jul-01 (JD 2459396.5)
    Uncertainty parameter6
    Observation arc0.9 days[2]
    Aphelion1.35 AU (Q)
    Perihelion0.6139 AU (q)

    Semi-major axis

    		0.98 AU (a)
    Eccentricity0.3750 (e)

    Orbital period (sidereal)

    		0.97 years

    Mean anomaly

    		312.8° (M)
    Inclination10.19° (i)

    Longitude of ascending node

    		211.6° (Ω)

    Argument of perihelion

    		66.27° (ω)
    Earth MOID0.000064 AU (9,600 km)
    Jupiter MOID3.7 AU (550,000,000 km)
    Physical characteristics
    Dimensions
    • ~2 m (7 ft)[2]
  • 1–3 meters

    • Absolute magnitude (H)

    		31.8[3][4]

    2021 UA1 is a small (~2 meter) near-Earth object that passed about 3047 km from the surface of Earth while passing over Antarctica on 25 October 2021 around 03:07 UT.[5][a] Given the small size of the asteroid it only reached the brightness of Pluto at around apparent magnitude 14.[5] Since it approached from the direction of the Sun, it was not discovered until 4 hours after closest approach.[1]

    Closest non-impacting asteroids to Earth, except Earth-grazing fireballs
    (using JPL SBDB numbers and Earth radius of 6,378 km)
    Asteroid Date Distance from
    surface of Earth     		Uncertainty in
    approach distance     		Observation arc Reference
    2020 VT4 2020-11-13 17:21 368 km ±11 km 5 days (34 obs) data
    2020 QG 2020-08-16 04:09 2939 km ±11 km 2 days (35 obs) data
    2021 UA1 2021-10-25 03:07 3049 km ±10 km 1 day (22 obs) data
    2023 BU 2023-01-27 00:29 3589 km ±<1 km 10 days (231 obs) data
    2011 CQ1 2011-02-04 19:39 5474 km ±5 km 1 day (35 obs) data
    2019 UN13 2019-10-31 14:45 6235 km ±189 km 1 day (16 obs) data
    2008 TS26 2008-10-09 03:30 6260 km ±970 km 1 day (19 obs) data
    2004 FU162 2004-03-31 15:35 6535 km ±13000 km 1 day (4 obs) data

    The 2021 Earth approach lifted the orbit and increased the orbital period from 356 days to 413 days.[6] This changed it from an Aten asteroid to an Apollo asteroid.

    Orbital Elements
    Parameter Epoch Period
    (p)     		Aphelion
    (Q)     		Perihelion
    (q)     		Semi-major axis
    (a)     		Eccentricity
    (e)     		Inclination
    (i)
    Units (days) AU (°)
    Pre-flyby 2021-Jul-01[3] 355.6 1.351 0.614 0.982 0.3750 10.19°
    Post-flyby 2022-Jan-01[6] 413.1 1.525 0.646 1.086 0.4046 0.006°
    Animation of 2021 UA1's orbit around Sun - 2021 Earth approach
      2021 UA1 ·   Mercury  ·   Venus  ·   Earth ·   Mars  ·   Sun

    Notes[edit]

    1. ^ Geocentric approach distance 0.000063 AU – 6378 km (Earth radius) is 3047 km. It passed within 4 degrees of the South celestial pole near closest approach.

    References[edit]

    1. ^ a b "MPEC 2021-U95 : 2021 UA1". IAU Minor Planet Center. 26 October 2021. Retrieved 26 October 2021. (K21U01A)
  • ^ a b c "Earth Impact Risk Summary: 2021 UA1". NASA/JPL Near-Earth Object Program Office. Retrieved 26 October 2021.
  • ^ a b c "JPL Small-Body Database Browser: (2021 UA1)" (Under Close Approach Data select km for distance units). Jet Propulsion Laboratory. Retrieved 26 October 2021.
  • ^ "2021 UA1 Orbit". Minor Planet Center. Retrieved 26 October 2021.
  • ^ a b "Horizons Batch for 2021-10-25 03:06 UT". JPL Horizons. Archived from the original on 26 October 2021. Retrieved 26 October 2021.
  • ^ a b "Horizons Batch showing epoch 2021-Jul-01 and 2022-Jan-01". JPL Horizons. Retrieved 26 October 2021.

    • External links[edit]


    Retrieved from "https://en.wikipedia.org/w/index.php?title=2021_UA1&oldid=1195681428"
    Categories: 
    ●Aten asteroids
     ●Minor planet object articles (unnumbered)
     ●Potential impact events caused by near-Earth objects
     ●Near-Earth objects in 2021
     ●Astronomical objects discovered in 2021
     Hidden categories: 
    ●Articles with short description
     ●Short description matches Wikidata
     ●Use dmy dates from October 2021
     ●JPL Small-Body Database ID same as Wikidata
     ●Articles with JPL SBDB identifiers
      


    ●This page was last edited on 14 January 2024, at 21:35 (UTC).
    ●Text is available under the Creative Commons Attribution-ShareAlike License 4.0; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.


    ●Privacy policy
    ●About Wikipedia
    ●Disclaimers
    ●Contact Wikipedia
    ●Code of Conduct
    ●Developers
    ●Statistics
    ●Cookie statement
    ●Mobile view


    Wikimedia Foundation
    Powered by MediaWiki