View source for Astronomy:(5645) 1990 SP

{{Infobox planet
 | minorplanet     = yes
 | name            = (5645) 1990 SP
 | background      = #FFC2E0
 | image           = 
 | image_size      = 
 | caption         = 
 | discovery_ref   = <ref name="jpldata" />
 | discovered      = 20 September 1990
 | discoverer      = R. H. McNaught
 | discovery_site  = Siding Spring Obs.
 | mpc_name        = (5645) 1990 SP
 | alt_names       = 1990 SP
 | pronounced      = 
 | named_after     = 
 | mp_category     = Apollo{{·}}[[Astronomy:Near-Earth object|NEO]]<ref name="MPC-5645" />
 | orbit_ref       = <ref name="jpldata" />
 | epoch           = 4 September 2017 ([[Astronomy:Julian day|JD]] 2458000.5)
 | uncertainty     = 0
 | observation_arc = 40.89 yr (14,935 days)
 | aphelion        = 1.8798 [[Astronomy:Astronomical unit|AU]]
 | perihelion      = 0.8302 AU
 | semimajor       = 1.3550 AU
 | eccentricity    = 0.3873
 | period          = 1.58 [[Astronomy:Julian year|yr]] (576 days)
 | mean_anomaly    = 339.42[[Degree (angle)|°]]
 | mean_motion     = {{Deg2DMS|0.6249|sup=ms}} / day
 | inclination     = 13.507°
 | asc_node        = 45.762°
 | arg_peri        = 48.178°
 | moid            = 0.0537 AU
 | dimensions      = {{val|1.648|}} km<ref name="Pravec-2012b" /><br />1.65 km {{small|(taken)}}<ref name="lcdb" /><br />{{val|1.668|0.018}} km<ref name="WISE" /><ref name="Mainzer-2011" /><br />{{val|1.849|0.334}} km<ref name="Mainzer-2012" /><br />{{val|2.20|0.74}} km<ref name="Mueller-2011a" />
 | rotation        = {{val|30.39|0.04}} [[Hour|h]]<ref name="Pravec-2005a" />
 | albedo          = {{val|0.06|0.08}}<ref name="Thomas-2011b" /><br />{{val|0.062|0.079}}<ref name="Mueller-2011a" /><br />{{val|0.068|0.032}}<ref name="Mainzer-2012" /><br />{{val|0.0827|}}<ref name="Pravec-2012b" /><br />{{val|0.121|0.022}}<ref name="WISE" /><ref name="Mainzer-2011" />
 | spectral_type   = [[Astronomy:P-type asteroid|P]]<ref name="Thomas-2011b" />{{·}}CXT<ref name="Thomas-2014" />{{·}}[[Astronomy:S-type asteroid|S]]<ref name="lcdb" />
 | abs_magnitude   = {{val|16.75|0.2}} {{small|(R)}}<ref name="Pravec-2005a" />{{·}}16.8<ref name="WISE" />{{·}}17.1<ref name="jpldata" />{{·}}{{val|17.20|0.3}}<ref name="Mainzer-2012" />{{·}}{{val|17.24|0.206}}<ref name="Pravec-2012b" /><ref name="lcdb" />
}}

'''(5645) 1990 SP''' is an eccentric and tumbling [[Astronomy:Asteroid|asteroid]], classified as [[Astronomy:Near-Earth object|near-Earth object]] of the [[Astronomy:Apollo asteroid|Apollo group]], approximately 1.7 kilometers in diameter. It was discovered on 20 September 1990, by Scottish–Australian astronomer Robert McNaught at the Siding Spring Observatory in Canberra, Australia.<ref name="MPC-5645" /> Scientists have said that it has a '1 in 364 billion chance' of colliding with the [[Astronomy:Earth|Earth]].

== Orbit and classification ==

The asteroid orbits the Sun at a distance of 0.8–1.9&nbsp;[[Astronomy:Astronomical unit|AU]] once every 1 years and 7 months (576 days). Its orbit has an [[Astronomy:Orbital eccentricity|eccentricity]] of 0.39 and an [[Astronomy:Orbital inclination|inclination]] of 14[[Degree (angle)|°]] with respect to the [[Astronomy:Ecliptic|ecliptic]].<ref name="jpldata" />

=== Close approaches ===

This near-Earth asteroid has an Earth [[Astronomy:Minimum orbit intersection distance|minimum orbit intersection distance]] of {{convert|0.055|AU|km|abbr=on}}, only slightly above the threshold minimum distance of 19.5 [[Astronomy:Lunar distance|lunar distances]] (0.05&nbsp;AU) to make it a [[Astronomy:Potentially hazardous object|potentially hazardous object]]. It also makes close approaches to Mars. On 14 April 1969, it passed the Red Planet at only {{convert|0.013|AU|km|abbr=on|sigfig=2}}.<ref name="jpldata" />

=== Precovery ===

Published by the [[Astronomy:Digitized Sky Survey|Digitized Sky Survey]] (DSS), a first [[Astronomy:Precovery|precovery]] was taken at the discovering observatory in 1974, extending the asteroid's [[Astronomy:Observation arc|observation arc]] by 16 years prior to its discovery.<ref name="MPC-5645" />

== Physical characteristics ==

The stony [[Astronomy:S-type asteroid|S-type asteroid]] is also characterized as a [[Astronomy:P-type asteroid|P-type]], based on post-cryogenic observations by the [[Astronomy:Spitzer Space Telescope|Spitzer Space Telescope]],<ref name="Thomas-2011b" /> while observations at the [[Organization:NASA Infrared Telescope Facility|NASA Infrared Telescope Facility]] using its [[Organization:NASA Infrared Telescope Facility#SpeX|SpeX instrument]] during a follow-up campaign of the Spitzer-observed objects between 2009 and 2012, gave it a C/X/T spectral type.<ref name="Thomas-2014" />

=== Rotation ===

In April 2002, Czech astronomer [[Biography:Petr Pravec|Petr Pravec]] obtained a rotational [[Astronomy:Lightcurve|lightcurve]] from a photometric observations, which gave a relatively long [[Rotation period|period]] of {{val|30.39|0.04}} hours with a brightness variation of 0.7 in [[Astronomy:Magnitude|magnitude]] ({{small|U=2}}). The observations have also shown that the body is most likely in a tumbling motion.<ref name="lcdb" /><ref name="Pravec-2005a" />

=== Diameter and albedo ===

Estimates for the body's diameter range from 1.6 to 2.2 kilometers with an [[Astronomy:Astronomical albedo|albedo]] for its surface between 0.06 and 0.12, according to observations made by the [[Astronomy:NEOWISE|NEOWISE]] mission of NASA's [[Astronomy:Wide-field Infrared Survey Explorer|Wide-field Infrared Survey Explorer]] and by the Spitzer Space Telescope.<ref name="Pravec-2012b" /><ref name="WISE" /><ref name="Mainzer-2011" /><ref name="Mainzer-2012" /><ref name="Mueller-2011a" /> The ''Collaborative Asteroid Lightcurve Link'' takes the revised WISE data – an albedo of 0.0872 and a diameter of 1.65 kilometers – as the best of all available results.<ref name="Pravec-2012b" /><ref name="lcdb" />

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

<ref name="jpldata">{{cite web
  |type       = 2015-07-04 last obs.
  |title      = JPL Small-Body Database Browser: 5645 (1990 SP)
  |url        = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2005645
  |publisher  = [[Organization:Jet Propulsion Laboratory|Jet Propulsion Laboratory]]
  |accessdate = 26 May 2017}}</ref>

<ref name="MPC-5645">{{cite web
  |title      = 5645 (1990 SP)
  |work       = Minor Planet Center
  |url        = https://www.minorplanetcenter.net/db_search/show_object?object_id=5645
  |accessdate = 29 June 2016}}</ref>

<ref name="lcdb">{{cite web
  |title      = LCDB Data for (5645) 
  |publisher  = Asteroid Lightcurve Database (LCDB)
  |url        = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=5645%7C
  |accessdate = 29 June 2016}}</ref>

<ref name="Mueller-2011a">{{Cite journal
  |display-authors = 6
  |first1     = Michael |last1 = Mueller
  |first2     = M. |last2 = Delbo'
  |first3     = J. L. |last3 = Hora
  |first4     = D. E. |last4 = Trilling
  |first5     = B. |last5 = Bhattacharya
  |first6     = W. F. |last6 = Bottke
  |first7     = S. |last7 = Chesley
  |first8     = J. P. |last8 = Emery
  |first9     = G. |last9 = Fazio
  |first10    = A. W. |last10 = Harris
  |first11    = A. |last11 = Mainzer
  |first12    = M. |last12 = Mommert
  |first13    = B. |last13 = Penprase
  |first14    = H. A. |last14 = Smith
  |first15    = T. B. |last15 = Spahr
  |first16    = J. A. |last16 = Stansberry
  |first17    = C. A. |last17 = Thomas
  |date       = April 2011
  |title      = ExploreNEOs. III. Physical Characterization of 65 Potential Spacecraft Target Asteroids
  |journal    = The Astronomical Journal
  |volume     = 141
  |issue      = 4
  |page       = 9
  |bibcode    = 2011AJ....141..109M
  |doi        = 10.1088/0004-6256/141/4/109|url = https://authors.library.caltech.edu/23152/1/Mueller2011p13239Astron_J.pdf }}</ref>

<ref name="Pravec-2012b">{{Cite journal
  |first1     = Petr |last1 = Pravec
  |first2     = Alan W. |last2 = Harris
  |first3     = Peter |last3 = Kusnirák
  |first4     = Adrián |last4 = Galád
  |first5     = Kamil |last5 = Hornoch
  |date       = September 2012
  |title      = Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations
  |journal    = Icarus
  |volume     = 221
  |issue      = 1
  |pages      = 365–387
  |bibcode    = 2012Icar..221..365P
  |doi        = 10.1016/j.icarus.2012.07.026}}</ref>

<ref name="Mainzer-2012">{{Cite journal
  |display-authors = 6
  |first1     = A. |last1 = Mainzer
  |first2     = T. |last2 = Grav
  |first3     = J. |last3 = Masiero
  |first4     = J. |last4 = Bauer
  |first5     = R. M. |last5 = Cutri
  |first6     = R. S. |last6 = McMillan
  |first7     = C. R. |last7 = Nugent
  |first8     = D. |last8 = Tholen
  |first9     = R. |last9 = Walker
  |first10    = E. L. |last10 = Wright
  |date       = November 2012
  |title      = Physical Parameters of Asteroids Estimated from the WISE 3-Band Data and NEOWISE Post-Cryogenic Survey
  |journal    = The Astrophysical Journal Letters
  |volume     = 760
  |issue      = 1
  |page       = 6
  |bibcode    = 2012ApJ...760L..12M
  |doi        = 10.1088/2041-8205/760/1/L12
  |arxiv = 1210.0502 |s2cid = 41459166 }}</ref>

<ref name="WISE">{{cite journal
  |display-authors = 6
  |first1     = A. |last1 = Mainzer
  |first2     = T. |last2 = Grav
  |first3     = J. |last3 = Masiero
  |first4     = E. |last4 = Hand
  |first5     = J. |last5 = Bauer
  |first6     = D. |last6 = Tholen
  |first7     = R. S. |last7 = McMillan
  |first8     = T. |last8 = Spahr
  |first9     = R. M. |last9 = Cutri
  |first10    = E. |last10 = Wright
  |first11    = J. |last11 = Watkins
  |first12    = W. |last12 = Mo
  |first13    = C. |last13 = Maleszewski
  |date       = November 2011
  |title      = NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results
  |journal    = The Astrophysical Journal
  |volume     = 741
  |issue      = 2
  |page       = 25
  |bibcode    = 2011ApJ...741...90M
  |doi        = 10.1088/0004-637X/741/2/90
  |arxiv      = 1109.6407|s2cid = 118700974 }}</ref>

<ref name="Pravec-2005a">{{Cite journal
  |display-authors = 6
  |first1     = P. |last1 = Pravec
  |first2     = A. W. |last2 = Harris
  |first3     = P. |last3 = Scheirich
  |first4     = P. |last4 = Kusnirák
  |first5     = L. |last5 = Sarounová
  |first6     = C. W. |last6 = Hergenrother
  |first7     = S. |last7 = Mottola
  |first8     = M. D. |last8 = Hicks
  |first9     = G. |last9 = Masi
  |first10    = Yu. N. |last10 = Krugly
  |first11    = V. G. |last11 = Shevchenko
  |first12    = M. C. |last12 = Nolan
  |first13    = E. S. |last13 = Howell
  |first14    = M. |last14 = Kaasalainen
  |first15    = A. |last15 = Galád
  |first16    = P. |last16 = Brown
  |first17    = D. R. |last17 = DeGraff
  |first18    = J. V. |last18 = Lambert
  |first19    = W. R. |last19 = Cooney
  |first20    = S. |last20 = Foglia
  |date       = January 2005
  |title      = Tumbling asteroids
  |journal    = Icarus
  |volume     = 173
  |issue      = 1
  |pages      = 108–131
  |bibcode    = 2005Icar..173..108P
  |doi        = 10.1016/j.icarus.2004.07.021}}</ref>

<ref name="Thomas-2011b">{{Cite journal
  |display-authors = 6
  |first1     = C. A. |last1 = Thomas
  |first2     = D. E. |last2 = Trilling
  |first3     = J. P. |last3 = Emery
  |first4     = M. |last4 = Mueller
  |first5     = J. L. |last5 = Hora
  |first6     = L. A. M. |last6 = Benner
  |first7     = B. |last7 = Bhattacharya
  |first8     = W. F. |last8 = Bottke
  |first9     = S. |last9 = Chesley
  |first10    = M. |last10 = Delbó
  |first11    = G. |last11 = Fazio
  |first12    = A. W. |last12 = Harris
  |first13    = A. |last13 = Mainzer
  |first14    = M. |last14 = Mommert
  |first15    = A. |last15 = Morbidelli
  |first16    = B. |last16 = Penprase
  |first17    = H. A. |last17 = Smith
  |first18    = T. B. |last18 = Spahr
  |first19    = J. A. |last19 = Stansberry
  |date       = September 2011
  |title      = ExploreNEOs. V. Average Albedo by Taxonomic Complex in the Near-Earth Asteroid Population
  |journal    = The Astronomical Journal
  |volume     = 142
  |issue      = 3
  |page       = 12
  |bibcode    = 2011AJ....142...85T
  |doi        = 10.1088/0004-6256/142/3/85|doi-access= free
  }}</ref>

<ref name="Thomas-2014">{{Cite journal
  |first1     = Cristina A. |last1 = Thomas
  |first2     = Joshua P. |last2 = Emery
  |first3     = David E. |last3 = Trilling
  |first4     = Marco |last4 = Delbó
  |first5     = Joseph L. |last5 = Hora
  |first6     = Michael |last6 = Mueller
  |date       = January 2014
  |title      = Physical characterization of Warm Spitzer-observed near-Earth objects
  |journal    = Icarus
  |volume     = 228
  |pages      = 217–246
  |bibcode    = 2014Icar..228..217T
  |doi        = 10.1016/j.icarus.2013.10.004
  |arxiv      = 1310.2000|s2cid = 119278697
 }}</ref>

<ref name="Mainzer-2011">{{Cite journal
  |display-authors = 6
  |first1     = A. |last1 = Mainzer
  |first2     = T. |last2 = Grav
  |first3     = J. |last3 = Bauer
  |first4     = J. |last4 = Masiero
  |first5     = R. S. |last5 = McMillan
  |first6     = R. M. |last6 = Cutri
  |first7     = R. |last7 = Walker
  |first8     = E. |last8 = Wright
  |first9     = P. |last9 = Eisenhardt
  |first10    = D. J. |last10 = Tholen
  |first11    = T. |last11 = Spahr
  |first12    = R. |last12 = Jedicke
  |first13    = L. |last13 = Denneau
  |first14    = E. |last14 = DeBaun
  |first15    = D. |last15 = Elsbury
  |first16    = T. |last16 = Gautier
  |first17    = S. |last17 = Gomillion
  |first18    = E. |last18 = Hand
  |first19    = W. |last19 = Mo
  |first20    = J. |last20 = Watkins
  |first21    = A. |last21 = Wilkins
  |first22    = G. L. |last22 = Bryngelson
  |first23    = A. |last23 = Del Pino Molina
  |first24    = S. |last24 = Desai
  |first25    = M. |last25 = Gómez Camus
  |first26    = S. L. |last26 = Hidalgo
  |first27    = I. |last27 = Konstantopoulos
  |first28    = J. A. |last28 = Larsen
  |first29    = C. |last29 = Maleszewski
  |first30    = M. A. |last30 = Malkan
  |first31    = J.-C. |last31 = Mauduit
  |first32    = B. L. |last32 = Mullan
  |first33    = E. W. |last33 = Olszewski
  |first34    = J. |last34 = Pforr
  |first35    = A. |last35 = Saro
  |first36    = J. V. |last36 = Scotti
  |first37    = L. H. |last37 = Wasserman
  |date       = December 2011
  |title      = NEOWISE Observations of Near-Earth Objects: Preliminary Results
  |journal    = The Astrophysical Journal
  |volume     = 743
  |issue      = 2
  |page       = 17
  |bibcode    = 2011ApJ...743..156M
  |doi        = 10.1088/0004-637X/743/2/156
  |arxiv      = 1109.6400|s2cid = 239991 }}</ref>

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

== External links ==
* [http://www.minorplanet.info/PHP/lcdbsummaryquery.php Asteroid Lightcurve Database (LCDB)], query form ([http://www.minorplanet.info/lightcurvedatabase.html info] {{Webarchive|url=https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html |date=16 December 2017 }})
* [https://books.google.com/books?id=aeAg1X7afOoC&pg Dictionary of Minor Planet Names], Google books
* [http://obswww.unige.ch/~behrend/page_cou.html Asteroids and comets rotation curves, CdR] – Observatoire de Genève, Raoul Behrend
* {{NeoDys|5645}}
* {{ESA-SSA|5645|1990SP}}
* {{JPL small body}}

{{Small Solar System bodies}}

{{DEFAULTSORT:1990 SP}}
[[Category:Apollo asteroids|005645]]

{{Sourceattribution|(5645) 1990 SP}}