View source for 2020 HS7

{{short description|Near-Earth asteroid}}
{{DISPLAYTITLE:{{mp|2020 HS|7}}}}
{{Use dmy dates|date=July 2022}}
{{Infobox planet
 | minorplanet     = yes
 | name            = {{mp|2020 HS|7}}
 | background      = #FFC2E0
 | image           = 
 | image_size      = 
 | caption         = 
 | discovery_ref   = <ref name="MPC-object"/><ref name="MPEC-2020-H212"/>
 | discoverer      = [[Pan-STARRS 2]]
 | discovery_site  = [[Haleakala Observatory|Haleakala Obs.]]
 | discovered      = 27 April 2020
 | mpc_name        = {{mp|2020 HS|7}}
 | alt_names       = 
 | pronounced      = 
 | named_after     = 
 | mp_category     = {{nowrap|[[Near-Earth object|NEO]]{{·}}[[Apollo asteroid|Apollo]]<ref name="jpldata"/><ref name="MPC-object"/>}}
 | orbit_ref       = <ref name="jpldata"/>
 | epoch           = 9 August 2022 ([[Julian day|JD]] 2459800.5)
 | uncertainty     = 6
 | observation_arc = 1 day
 | aphelion        = 2.904 AU
 | perihelion      = 0.793 AU
 | semimajor       = 1.849
 | eccentricity    = 0.5709
 | period          = 2.51 yr (918 days)
 | mean_anomaly    = 308.988[[Degree (angle)|°]]
 | mean_motion     = {{Deg2DMS|0.3921687|sup=ms}} / day
 | inclination     = 4.732°
 | asc_node        = 38.531°
 | arg_peri        = 245.692°
 | dimensions      = ''a''/''b'' ≥ 1.04<ref name="Beniyama2022"/>
 | mean_diameter   = {{val|4|-|8|ul=m}}<ref name="space_050520" />
 | rotation        = {{val|2.9945|0.0002|u=s}}<ref name="Beniyama2022"/><br/>{{val|2.9938|0.0002|u=s}}<ref name="Beniyama2022"/>
 | albedo          = 
 | spectral_type   = 
 | magnitude       = 
 | abs_magnitude   = {{val|29.10|0.36}}<ref name="jpldata"/>
}}

'''{{mp|2020 HS|7}}''' is a very small asteroid classified as a [[near-Earth object]] of the Earth-crossing [[Apollo asteroid|Apollo group]]. When it was discovered by the [[Pan-STARRS 2]] survey on 27 April 2020, the asteroid was initially calculated to have a 10% chance of impact with Earth before being ruled out by improved [[orbit determination]]s from additional observations.<ref name="ssa_072920"/> Although there is now no risk of impact with Earth, it did make a close approach {{convert|42700|km|mi}} from Earth on 28 April 2020, with a flyby speed of {{convert|15.6|km/s|mi/s}} relative to Earth.<ref name="jpldata"/><ref name="space_042820"/><ref name="space_050520"/> The asteroid will not make any close encounters within {{convert|1|LD|km mi|lk=in}} of Earth in the next 100 years.<ref name="jpldata"/>

Observations by [[Kiso Observatory]] in [[Nagano Prefecture|Nagano, Japan]] show that the asteroid rotates extremely rapidly with a [[rotation period]] of 3 seconds, making it the [[List of fast rotators (minor planets)|fastest-rotating asteroid]] known {{as of|2022|lc=y}}.<ref name="Beniyama2022"/> No other near-Earth asteroid of similar size is known to have a rotation period shorter than 10 seconds, which could be attributed to the tangential component of the [[YORP effect]] accelerating their rotation far beyond this period.<ref name="Beniyama2022"/> The asteroid exhibits a very small [[light curve]] amplitude of 0.07 [[magnitude (astronomy)|magnitude]]s, which either implies a nearly spherical shape or a pole-on rotation during observations.<ref name="Beniyama2022"/>

== See also ==
* [[List of fast rotators (minor planets)]]
* [[List of asteroid close approaches to Earth in 2020]]

== References ==
{{reflist|refs=

<ref name="jpldata">{{cite web
 |type         = 2022-04-28 last obs.
 |title        = JPL Small-Body Database Browser: (2020 HS7)
 |url          = https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2020HS7&view=OPC
 |publisher    = [[Jet Propulsion Laboratory]]
 |accessdate   = 29 July 2020}}</ref>

<ref name="MPC-object">{{cite web
  |title      = 2020 HS7
  |url        = http://www.minorplanetcenter.net/db_search/show_object?object_id=2020+HS7
  |publisher  = Minor Planet Center
  |accessdate = 15 July 2022}}</ref>

<ref name="MPEC-2020-H212">{{cite web
 |title        = MPEC 2022-F48 : 2022 FD1
 |url          = https://minorplanetcenter.net/mpec/K20/K20HL2.html
 |work         = Minor Planet Electronic Circular
 |publisher    = Minor Planet Center
 |date         = 28 April 2020
 |accessdate   = 15 July 2022}}</ref>

<ref name="space_042820">{{cite web |last=Malik |first=Tariq |title=Small asteroid zips safely by Earth just ahead of a larger space rock's flyby |url=https://www.space.com/small-asteroid-2020-hs7-buzzes-earth-ahead-of-big-space-rock.html |website=[[Space.com]] |date=28 April 2020}}</ref>

<ref name="space_050520">{{cite web |last=Bartels |first=Meghan |title=Tiny asteroid's super-close Earth flyby shows planetary protection in action, scientists say |url=https://www.space.com/asteroid-2020-hs7-earth-close-flyby-planetary-protection.html |website=[[Space.com]] |date=5 May 2020}}</ref>

<ref name="ssa_072920">{{cite web |title=ESA space situational awareness 2020HS7 |url=http://neo.ssa.esa.int/search-for-asteroids?tab=summary&des=2020HS7 |publisher=[[European Space Agency]] |access-date=29 July 2020}}</ref>

<ref name="Beniyama2022">{{cite journal|title=Video observations of tiny near-Earth objects with Tomo-e Gozen|display-authors=etal|first1=Jin|last1=Beniyama|journal=Publications of the Astronomical Society of Japan |year=2022 |volume=74 |issue=4 |pages=877–903 |doi=10.1093/pasj/psac043 |arxiv=2207.07071}}</ref>

}}

== External links ==
* {{NeoDys|2020+HS7}}
* {{ESA-SSA|2020HS7}}
* {{JPL small body|id=54016805}}

{{2020 in space}}
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{{DEFAULTSORT:2020 HS7}}
[[Category:Apollo asteroids|#]]
[[Category:Minor planet object articles (unnumbered)]]
[[Category:Discoveries by Pan-STARRS|#]]
[[Category:Fast rotating minor planets|#]]
[[Category:Near-Earth objects in 2020|20200428]]
[[Category:Astronomical objects discovered in 2020|20200427]]