View source for 2019 UN13

{{short description|3rd closest non-impacting Earth approach}}
{{DISPLAYTITLE:{{mp|2019 UN|13}}}}
{{Use dmy dates|date=February 2020}}
{{Infobox planet
 | minorplanet     = yes
 | name            = {{mp|2019 UN|13}}
 | background      = #FFC2E0
 | image           = 
 | image_size      = 
 | caption         = 
 | discovery_ref   = &thinsp;<ref name="MPC-object" />
 | discoverer      = [[Catalina Sky Survey|CSS]] (Teddy Pruyne)
 | discovery_site  = [[Catalina Station|Catalina Stn.]]
 | discovered      = 31 October 2019<br />{{small|(first observed only)}}
 | mpc_name        = {{mp|2019 UN|13}}
 | alt_names       = C0PPEV1<ref>{{Cite web |url=https://projectpluto.com/neocp2/mpecs/C0PPEV1.htm |title=Pseudo-MPEC for C0PPEV1 |access-date=1 November 2019 |archive-date=1 November 2019 |archive-url=https://web.archive.org/web/20191101221212/https://projectpluto.com/neocp2/mpecs/C0PPEV1.htm |url-status=dead }}</ref>
 | mp_category     = [[Near-Earth object|NEO]]{{·}}[[Aten asteroid|Aten]]&thinsp;<ref name="MPC-object" /><ref name="jpldata" />
 | orbit_ref       = &thinsp;<ref name="jpldata" />
 | epoch           = 27 April 2019 ([[Julian day|JD]] 2458600.5)
 | uncertainty     = 7
 | observation_arc = 3.7 hours<ref name="MPC-object"/><br />(18 observations)
 | aphelion        = 1.3301 [[Astronomical unit|AU]]<br />{{small|(2.06 AU after passage)}}
 | perihelion      = 0.6463 AU
 | semimajor       = 0.9882 AU
 | eccentricity    = 0.3460
 | period          = 359 days
 | mean_anomaly    = 100.74[[Degree (angle)|°]]
 | mean_motion     = {{Deg2DMS|1.0034|sup=ms}} / day
 | inclination     = 1.4925°
 | asc_node        = 217.58°
 | arg_peri        = 291.05°
 | moid            = {{cvt|0.000005|AU|km|sigfig=1|abbr=unit}}
 | mean_diameter   = {{val|1|-|2|ul=m}}<ref name=sentry/><ref name=esa/><ref name=NEO-CA/>
 | mass            = {{val|2800|ul=kg}} {{small|(est.)}}<ref name=sentry/>
 | rotation        = 
 | albedo          = 
 | spectral_type   = 
 | abs_magnitude   = 32.0<ref name="MPC-object" /><ref name="jpldata" />
}}

'''{{mp|2019 UN|13}}''' is a small [[near-Earth asteroid]] roughly 1–2 meters in diameter. Even though the asteroid was in the night sky for months, it was fainter than the [[sky survey]] limit of [[apparent magnitude#24|apparent magnitude 24]] until 29 October 2019 when the asteroid was two million km from Earth.<ref name="NEODyS2019"/> It was discovered on October 31, 2019, passing 6,200&nbsp;km above Earth's surface.<ref>{{Cite web|url=https://www.cnet.com/news/spooky-halloween-asteroid-flyby-one-of-the-closest-near-misses-ever-seen/|title=Spooky Halloween asteroid flyby one of the closest near misses ever seen}}.</ref><ref>[https://twitter.com/tony873004/status/1190017524777111553 Newly-discovered #asteroid C0PPEV1] Twitter message</ref>

[[2020 QG]] and {{mpl|2011 CQ|1}} are the only asteroids known where the [[Curve fitting|nominal]] orbit passed closer to the surface of Earth.<ref name=NEO-CA>Go to https://cneos.jpl.nasa.gov/ca/ and for Table Settings select "Nominal distance <= 1 LD", "Past only" and sort by "CA distance nominal"</ref> Other asteroids that passed very close to Earth include {{mpl|2004 FU|162}}, [[2018 UA]], and {{mpl|2019 AS|5}}.

An [[Impact event|impact]] by {{mp|2019 UN|13}} would be less significant than the [[2018 LA]] impact.

==2019 flyby==
[[File:2019UN13-hover.png|640px]]
: 5 minute markers of trajectory above the earth near closest approach

==Orbit changes==
The close approach to Earth lifted the asteroid's [[aphelion]] point (furthest distance from the Sun) from 1.33 [[Astronomical unit|AU]] (inside the orbit of [[Mars]]) to 2.06 AU (near the edge of the inner [[asteroid belt]]). The approach changed the orbit from an [[Aten asteroid]] with a [[semi-major axis]] less than 1 AU to an [[Apollo asteroid]] with a semi-major axis greater than that of the Earth (&gt; 1 [[Astronomical unit|AU]]).
{| class="wikitable" style="font-size: 0.9em;"
|+[[Orbital elements]] for April 2019 and April 2020
!
! 2019<ref name="jpldata"/>
! 2020
|-
|Orbit type || [[Aten asteroid|Aten]] || [[Apollo asteroid|Apollo]]
|-
|[[Perihelion]]<br />(closest distance to the Sun) || 0.64 AU || 0.83 AU
|-
|[[Semi-major axis]]<br />(average distance from the Sun) || 0.98 AU || 1.4 AU
|-
|[[Aphelion]]<br />(furthest distance from the Sun) || 1.3 AU || 2.0 AU
|-
|[[Orbital period]] || 358 days || 637 days
|}

With the new orbit, {{mp|2019 UN|13}} will come to perihelion 0.83 AU from the Sun on 15 December 2019. Without [[Perturbation (astronomy)|perturbations]], the previous orbit would have come to perihelion in January 2020.

==Future==
There is a small chance the asteroid will pass {{cvt|0.0001|AU|km|sigfig=2|abbr=unit}} from Mars on 26 October 2023.<ref name="jpldata" /> There is also a 1 in 3 million chance the asteroid will impact Earth on 1 November 2111.<ref name=sentry/>

==See also== 
{{Closest non-impacting asteroids to Earth}}

==References==
{{reflist|30em|refs=

<ref name="jpldata">{{cite web
  |type       = 2019-10-31 last obs.
  |title      = JPL Small-Body Database Browser: (2019 UN13)
  |url        = https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2019UN13&view=OPC
  |publisher  = [[Jet Propulsion Laboratory]]
  |archive-url= https://web.archive.org/web/20191103201228/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2019UN13;cad=1
  |archive-date= 3 November 2019
  |url-status = live
  |access-date = 1 November 2019}}</ref>

<ref name="MPC-object">{{cite web
  |title      = 2019 UN13
  |work       = Minor Planet Center
  |url        = https://www.minorplanetcenter.net/db_search/show_object?object_id=2019+UN13
  |access-date = 1 November 2019}}</ref>

<ref name=sentry>{{cite web
  |title      = Earth Impact Risk Summary: 2019 UN13
  |publisher  = NASA/JPL Near-Earth Object Program Office
  |url        = https://cneos.jpl.nasa.gov/sentry/details.html#?des=2019%20UN13
  |archive-url= https://archive.today/20191102135851/https://cneos.jpl.nasa.gov/sentry/details.html%23?des=2019%20UN13
  |archive-date= 2 November 2019
  |url-status = live
  |access-date = 2 November 2019}}</ref>

<ref name=esa>{{cite web
  |title      = esa: 2019 UN13
  |publisher  = ESA
  |url        = http://neo.ssa.esa.int/search-for-asteroids?tab=summary&des=2019UN13
  |archive-url= https://archive.today/20191103153609/http://neo.ssa.esa.int/search-for-asteroids?tab=summary&des=2019UN13
  |archive-date= 3 November 2019
  |url-status = live
  |access-date = 3 November 2019}}</ref>

<ref name="NEODyS2019">{{cite web
  |title=2019UN13 Ephemerides for October 2019
  |publisher=[[NEODyS]] (Near Earth Objects – Dynamic Site)
  |url=https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2019UN13&oc=500&y0=2019&m0=10&d0=1&h0=0&mi0=0&y1=2019&m1=11&d1=3&h1=0&mi1=0&ti=1.0&tiu=days
  |access-date=2019-11-03}}</ref>

}} <!-- end of reflist -->

==External links==
* [https://www.minorplanetcenter.net/mpec/K19/K19V09.html MPEC 2019-V09 : 2019 UN13], ''[[Minor Planet Electronic Circular]]'', 1 November 2019
* [https://catalina.lpl.arizona.edu/news/2019/11/catalina-sky-survey-scares-tiny-earth-grazing-halloween-asteroid Catalina Sky Survey Scares-Up Tiny Earth-Grazing Halloween Asteroid], CSS, 1 November 2019
* [https://earthsky.org/space/near-earth-asteroid-close-pass-oct-2019-c0ppev1 Small asteroid paid a heavy price for almost striking Earth Thursday], EarthSky, 1 November 2019
* [https://www.deseret.com/2019/11/1/20944310/this-small-asteroid-almost-struck-earth-on-halloween This small asteroid almost struck Earth on Halloween], Deseret News, 1 November 2019
* [http://iawn.net/close-approaches/2019-UN13_geometry.shtml 2019 UN13 Geometry], IAWN – International Asteroid Warning Network
* {{NeoDys|2019+UN13}}
* {{JPL small body|id=3892165}}

{{2019 in space}}

{{DEFAULTSORT:2019 UN13}}
[[Category:Astronomical objects discovered in 2019|20191031]]
[[Category:Aten asteroids|#]]
[[Category:Discoveries by the Catalina Sky Survey]]
[[Category:Minor planet object articles (unnumbered)]]
[[Category:Potential impact events caused by near-Earth objects]]