View source for 2018 VP1

{{short description|Apollo near-Earth asteroid}}
{{DISPLAYTITLE:{{mp|2018 VP|1}}}}
{{Use dmy dates|date=July 2019}}
{{Infobox planet
| minorplanet = yes
| background = #FFC2E0
| name = {{mp|2018 VP|1}}
| discovery_ref = <ref name="MPEC2018-V42"/>
| discoverer = [[Zwicky Transient Facility]]
| discovery_site = [[Palomar Mountain]] ([[List of observatory codes|I43]])
| discovered = 3 November 2018
| mpc_name = {{mp|2018 VP|1}}
| mp_category = {{Hlist
 | [[Apollo asteroid|Apollo]]
 | [[Near-Earth object|NEO]]<ref name="jpldata"/>
 | [[Sentry (monitoring system)|risk listed]]<ref name=sentry/>
 }}
| orbit_ref = <ref name="jpldata"/>
| epoch = 2020-May-31 ([[Julian day|JD]]&nbsp;2459000.5)
| uncertainty = 7
| observation_arc = 12.9 days<ref name=sentry/>
| moid = 8300&nbsp;km
| jupiter_moid = {{Convert|3.1|AU|km|abbr=on}}
| aphelion = {{Convert|2.2703|AU|km|abbr=on|lk=on}} (Q)
| perihelion = {{Convert|0.90513|AU|km|abbr=on}} (q)
| semimajor = {{Convert|1.5877|AU|km|abbr=on}} (a)
| eccentricity = 0.42992 (e)
| period = 2.00&nbsp;[[Julian year (astronomy)|yr]]
| inclination = 3.2419° (i)
| asc_node = 39.816° (Ω)
| mean_anomaly = 300.72[[Degree (angle)|°]] (M)
| arg_peri = 315.12° (ω)
| dimensions = ~{{convert|2|m|ft|sigfig=1|abbr=off|sp=us}}<ref name=sentry/><br />2–4 meters (CNEOS)
| abs_magnitude = 30.9<ref name=jpldata/>
}}
'''{{mp|2018 VP|1}}''' is an [[List of Apollo asteroids|Apollo]] [[near-Earth asteroid]] roughly {{convert|2|m|ft|sigfig=1|abbr=off|sp=us}} in diameter. The asteroid had a 0.41% chance (1 in 240) of [[Impact event|impacting]] Earth on 2 November 2020 01:12 UT.<ref name=sentry/> It was discovered on 3 November 2018 when it was about {{convert|0.003|AU|km mi|abbr=on}} from Earth and had a [[solar elongation]] of 165 degrees. The asteroid has a short 12.9 day [[observation arc]]. It was last observed on 16 November 2018 by the [[European Southern Observatory]] [[Very Large Telescope]] at [[apparent magnitude]] 26 pushing the telescope close to the [[limiting magnitude]].

The [[JPL Horizons On-Line Ephemeris System|JPL Horizons]] 2 November 2020 [[Curve fitting|nominal]] Earth approach was estimated as roughly {{convert|0.0028|AU|km mi|abbr=on}}.<ref name="jpldata" /> The line of variations (LOV, uncertainty region<ref>{{Cite web|title=Sentry: Earth Impact Monitoring|url=https://cneos.jpl.nasa.gov/sentry/intro.html|access-date=2020-09-04|website=cneos.jpl.nasa.gov}}</ref>) allowed the asteroid to impact Earth{{efn|name=sbdb-min}} or pass as far away as {{convert|0.025|AU|km mi|abbr=on}}.<ref name="jpldata" /> Its diameter of 2–4 meters makes it approximately 100–1000 times less massive than the 20-meter [[Chelyabinsk meteor]].{{efn|name=volume}} An Earth-[[Impact event|impact]] by this asteroid, assuming it is a common primitive [[chondrite]], might rattle some windows after an airburst and/or drop [[pebble]]-sized meteorites on roof tops after [[Dark flight (astronomy)|dark flight]].<ref name="AMS" />

Preliminarily results are that nothing was detected via [[infrasound]] or atmospheric flash monitors.<ref>[https://twitter.com/michael_w_busch/status/1323344713022345219 Astronomer Michael Busch]</ref> The asteroid was not visually recovered.

== Return ==
{{mp|2018 VP|1}} has a low 3.2° [[orbital inclination]] with respect to the [[ecliptic plane]] and an Earth-[[Minimum orbit intersection distance|MOID]] of only 9700&nbsp;km.<ref name=jpldata/> Since the asteroid approached Earth in November 2018 and has a 2.00 year [[orbital period]], the asteroid approached Earth again around 2 November 2020 (±3 days).<ref name=jpldata/>{{efn|name=sbdb-date}} Where Earth will be on a given date is known. However, given the short observation arc and the two years since it was seen at all, the location of the asteroid along its orbit was imprecisely known.

The asteroid intersected Earth's orbit. A slight variation in the known orbit of the asteroid can cause it to be early (NEODyS solution), right on time (Sentry solution), or late (JPL solution).{{efn|name=crossing}} The nominal [[NEODyS]] 1 November 2020 23:54 UT Earth approach is {{convert|0.0004|AU|km mi|abbr=on}}.<ref name="NEODyS-CA" /> The [[Sentry Risk Table]] showed an estimated 1 in 240 chance of Earth impact on 2 November 2020 1:12 UT.<ref name="sentry" /> The nominal JPL Horizons 2 November 2020 11:33 UT Earth approach was {{convert|0.0028|AU|km mi|abbr=on}} with a [[3-sigma]] uncertainty of {{Nowrap|± 4 million km}}.<ref name="jpldata" />

{|class="wikitable" style="text-align:center; font-size:0.9em;"
|+Line of variation (LOV) and different closest approaches
! Date and time
! Closest Earth approach
! Reference
|-
| 1 November 2020 23:54 || {{convert|0.0004|AU|km|abbr=on}} || NEODyS<ref name="NEODyS-CA"/>
|- bgcolor=#edf3fe
| 2 November 2020 01:12 || Impact scenario || Sentry<ref name=sentry/>{{efn|name=crossing}}
|-
| 2 November 2020 11:33 || {{convert|0.0028|AU|km|abbr=on}} || JPL SBDB<ref name=jpldata/>
|}

{{multiple image
| align = left
| direction = horizontal
| width = 300
| header = Animation of 2018 VP1's orbit
| image1 = Animation of 2018 VP1's orbit around Sun.gif
| caption1 = Around the Sun – close approach in 2018 and 2020
| image2 = Animation of 2018 VP1 close approach in November 2018.gif
| caption2 = Around the Earth – close approach in 2018
| image3 = Animation of 2018 VP1 close approach in November 2020.gif
| caption3 = Around the Earth – assumed close approach in 2020, but numerous other solutions fit

| footer = {{legend2|yellow|Sun}}{{·}}{{legend2| Royalblue | Earth}}{{·}}{{legend2| magenta| 2018 VP1}}{{·}}{{legend2| DarkKhaki| Moon}}
}}
{{clear}}

=== Impact line ===
The line of variation (LOV) passed across the [[Pacific Ocean]].<ref name="PeterThomas">[https://twitter.com/ptastro1/status/1154741054672756737 Path of risk (Risk Corridor)] (Peter Thomas, 26 July 2019)</ref>

The asteroid came to [[Opposition (planets)|opposition]] (opposite the Sun in the sky) at the end of May 2020 at an estimated [[apparent magnitude]] of ~31,<ref name="NEODyS2020"/> and as a moving object was much too faint for any telescope to detect. Large ground-based observatories take 10 hours to image a [[apparent magnitude#27|magnitude ~28]] object. The [[Hubble Space Telescope]] needs 3 weeks of [[exposure time]] to image [[apparent magnitude#31|magnitude 31]] objects. The November 2020 Earth approach was expected be hidden by the glare of the Sun due to the asteroid's low [[solar elongation]] in that time.<ref name="NEODyS2020"/>

Since the asteroid is only about {{convert|2|m|ft|sigfig=1|abbr=off|sp=us}} in diameter it is too small to do more than create a [[bolide]] and common [[strewn field]] similar to the [[Sutter's Mill meteorite]] or [[2014 AA]].<ref>{{cite web | url = https://www.clickondetroit.com/features/2020/08/21/an-asteroid-is-on-possible-collision-course-with-earth-this-november-should-we-be-worried/ | title = An asteroid is on possible collision course with Earth this November: Should we be worried? | last = Allen | first = Jeremy | website = ClickOnDetroit | date = 21 August 2020 | publisher = Graham Media Group | access-date = 2020-08-22}}</ref>

It is not categorized as a [[potentially hazardous object]] given the estimated size is smaller than the threshold for potentially hazardous objects which are estimated at more than 140 meters in diameter.

== See also ==
*{{mpl|2020 AP|1}}
*{{mpl|2006 QV|89}}
*{{mpl|2020 VV}}

== Notes ==
{{notelist|refs=

{{efn|name=sbdb-min|The [[JPL Small-Body Database]] for 2020-Nov-02 shows a minimum possible distance of {{Convert|0.000039|AU|km|abbr=on}} from the center of Earth, which is less than the 6371&nbsp;km radius of Earth.}}

{{efn|name=volume|Assuming the same density and given that the [[volume of a sphere]] <math>= \frac{\pi}{6}\ d^3</math>, 2018 VP1 would have a volume of 4–33&nbsp;m<sup>3</sup> and the [[Chelyabinsk meteor]] was ~4200&nbsp;m<sup>3</sup>.}}

{{efn|name=sbdb-date|The [[JPL Small-Body Database]] for 2020-Nov-02 shows the "Time Uncertainty" as 3_07:11 which is 3 days, 7 hours, and 11 minutes.}}

{{efn|name=crossing|Earth traveling at 30 km/s and with a diameter of 12,800&nbsp;km, only blocked the path of single virtual impactor for about 8 minutes (30*60*8). Due to a non-Earth like orbit, the virtual asteroids can only impact Earth for about ±10 minutes centered around the virtual impactor at 2 November 2020 01:12 UT. If 2018 VP1 was not crossing Earth's orbit during that time there could be no impact.}}

}} <!-- end of notelist -->

== References ==
{{Reflist|refs=

<ref name="MPEC2018-V42">{{cite web
  |title=MPEC 2018-V42 : 2018 VP1
  |publisher=IAU Minor Planet Center
  |date=2018-11-04
  |url=https://www.minorplanetcenter.net/mpec/K18/K18V42.html
  |accessdate=2019-07-22}} (K18V01P)</ref>

<ref name=sentry>{{cite web
  |title=Earth Impact Risk Summary: 2018 VP1
  |publisher=NASA/JPL Near-Earth Object Program Office
  |url=https://cneos.jpl.nasa.gov/sentry/details.html#?des=2018%20VP1
  |archive-url=https://archive.today/20190305080330/https://cneos.jpl.nasa.gov/sentry/details.html%23?des=2018%20VP1#?des=2018%20VP1
  |archive-date=5 March 2019
  |accessdate=2019-07-22
  |url-status=live
  }}</ref>

<ref name=jpldata>{{cite web
  |type=last observation: 2018-11-16; [[Observation arc|arc]]: 13 days
  |title=JPL Small-Body Database Browser: (2018 VP1)
  |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2018VP1;cad=1
  |publisher=[[Jet Propulsion Laboratory]]
  |archive-url=https://web.archive.org/web/20190721052345/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2018VP1;cad=1
  |archive-date=21 July 2019
  |accessdate=2019-07-22
  |url-status=live
  }}</ref>

<ref name="NEODyS-CA">{{cite web
  |title=2018VP1 Close Approaches
  |publisher=[[NEODyS]] (Near Earth Objects{{Snd}} Dynamic Site)
  |url=https://newton.spacedys.com/neodys/index.php?pc=1.1.8&n=2018VP1
  |archive-url=https://web.archive.org/web/20190721054108/https://newton.spacedys.com/neodys/index.php?pc=1.1.8&n=2018VP1
  |archive-date=2019-07-21
  |url-status=live
  |accessdate=2019-07-22}}</ref>

<ref name="NEODyS2020">{{cite web
  |title=2018VP1 Ephemerides for May–Nov 2020
  |publisher=[[NEODyS]] (Near Earth Objects{{Snd}} Dynamic Site)
  |url=https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2018VP1&oc=500&y0=2020&m0=5&d0=3&h0=0&mi0=0&y1=2020&m1=11&d1=2&h1=0&mi1=0&ti=3.0&tiu=days
  |archive-url=https://archive.today/20190721073352/https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2018VP1&oc=500&y0=2020&m0=5&d0=3&h0=0&mi0=0&y1=2020&m1=11&d1=2&h1=0&mi1=0&ti=3.0&tiu=days
  |archive-date=21 July 2019
  |accessdate=2019-07-22
  |url-status=live
  }}</ref>

<ref name="AMS">{{cite web
  |title=Can a meteorite dropping fireball be observed all the way to impact with the ground? (Dark Flight)
  |publisher=American Meteor Society
  |url=https://www.amsmeteors.org/fireballs/faqf/#8
  |accessdate=2020-08-23}}</ref>

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

== External links ==
* [https://www.minorplanetcenter.net/iau/lists/t_apollos.html List Of Apollo Minor Planets (by designation)], ''Minor Planet Center''
* {{NeoDys|2018+VP1}}
* {{JPL small body|id=3835977}}
* [http://iawn.net/close-approaches/2018-VP1_geometry.shtml IAWN: 2018 VP1 Geometry] (2018 Approach)
* [http://www.brera.mi.astro.it/sormano/teca.html Table of Asteroids Next Closest Approaches to the Earth] – Sormano Astronomical Observatory
* [http://www.hohmanntransfer.com/mn/18/18309_1105.htm#2018VP1 NEODyS (5 Nov 2018) with 1 day arc] – hohmanntransfer
* [https://www.youtube.com/watch?v=8M_27st1ZCI Asteroid Hazards, Part 3: Finding the Path] – YouTube video by the Minor Planet Center (26 August 2015)

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{{DEFAULTSORT:2018 VP1}}
[[Category:Apollo asteroids|#]]
[[Category:Minor planet object articles (unnumbered)]]
[[Category:Potential impact events caused by near-Earth objects]]
[[Category:Near-Earth objects in 2020|20201102]]
[[Category:Astronomical objects discovered in 2018|20181103]]