1620 Geographos

Asteroid October 2019 yes 1620 Geographos #FFC2E0 1620Geographos (Lightcurve Inversion).png Lightcurve-based 3D-model of Geographos A. G. WilsonR. Minkowski Palomar Observatory 14 September 1951 (1620) Geographos 1951 RA1983 CY 3 dʒ iː oʊ ˈ ɡ r æ f ɒ s National Geographic Society ApolloNEOPHA 4 September 2017 (JD 2458000.5) 0 65.37 yr (23,875 days) 31 August 1951 1.6629 AU 0.8276 AU 1.2453 AU 0.3354 1.39 yr (508 days) 246.00° 0.7093 ms / day 13.337° 337.20° 276.90° 0.0301 AU11.7 LD (5.0×2.0×2.1) ± 0.15 km 1.77 0.1 km1.87 0.05 km1.96 0.06 km2.5 km2.56 0.15 km 5.2220 0.0003 h5.22204 0.00007 hlcdb-Hamanowa-20115.22229 0.00004 h5.223 0.003 h5.223 0.005 h5.223 h5.223326 h5.223327 h5.223328 h5.224 0.007 h 0.260.290 0.0380.29 0.040.32 0.040.3258 0.051 Tholen SSMASS SSB–V 0.862B–V 0.896 0.009U–B 0.471V–R 0.462 0.005V–I 0.816 0.006 15.0915.4115.55 0.3715.6 1620 Geographos (dʒ iː oʊ ˈ ɡ r æ f ɒ s; provisional designation 1951 RA) is a highly elongated, stony asteroid, near-Earth object and potentially hazardous asteroid of the Apollo group, with a mean diameter of approximately 2.5 km on. It was discovered on 14 September 1951, by astronomers Albert George Wilson and Rudolph Minkowski at the Palomar Observatory in California, United States. The asteroid was named in honor of the National Geographic Society. Orbit and classification thumb|left|Animation of 1620 Geographos orbit 2010-2020 yellow Sun Lime Venus RoyalBlue Earth OrangeRed Mars Magenta 1620 Geographos Geographos orbits the Sun at a distance of 0.8–1.7 AU once every 1 years and 5 months (508 days). Its orbit has an eccentricity of 0.34 and an inclination of 13° with respect to the ecliptic. Its orbit is well-determined for the next several hundred years. Due to its high eccentricity, Geographos is also a Mars-crosser asteroid. The body's observation arc begins at Palomar, two weeks prior to its official discovery observation. Close approaches As a potentially hazardous asteroid, Geographos has a minimum orbital intersection distance (MOID) with Earth of less than 0.05 AU and a diameter of greater than 150 meters. The Earth-MOID is currently 0.0301 AU km on off 3, which translates into 11.7 lunar distances. In 1994, Geographos made its closest approach to Earth in two centuries at 5.0 million km – which will not be bettered until 2586. Failed Clementine mission Geographos was to be explored by the U.S.'s Clementine mission which was launched in January 1994. However, a malfunction in the spacecraft ended the mission before it could approach the asteroid.http://www.nasa.gov/mission_pages/LCROSS/searchforwater/clementine.html NASA - Clementine 24 May 2021 20 November 2022 https://web.archive.org/web/20221120010729/https://www.nasa.gov/mission_pages/LCROSS/searchforwater/clementine.html dead Physical characteristics Spectral type In the Tholen and SMASS classification, Geographos is an S-type asteroid. This means that it is highly reflective and composed of nickel-iron mixed with iron- and magnesium-silicates. Rotation period Since the 1970s, several rotational lightcurve of Geographos have been obtained from photometric observations. Lightcurve analysis gave a rotation period (retrograde sense of rotation) between 5.222 and 5.224 hours with a very high brightness variation between 1.02 and 2.03 magnitude (U=3/3/3/2/3/3/3).lcdb-Hamanowa-2011 The Yarkovsky effect is causing a decrease in the orbital semimajor axis of 27.4 5.7 m yr−1, while the YORP effect is increasing the asteroid's rotation at the rate of 1.14e−3 0.03 rad yr−2.10.1051/0004-6361/202141844 free Rotation acceleration of asteroids (10115) 1992 SK, (1685) Toro, and (1620) Geographos due to the YORP effect 2022 Ďurech J. Vokrouhlický D. Pravec P. Krugly Yu. N. Kim M.-J. Polishook D. Ayvazian V. V. Bonev T. Choi Y.-J. Datashvili D. G. Donchev Z. Ehgamberdiev S. A. Hornoch K. Inasaridze R. Ya. Kapanadze G. V. Kim D.-H. Kučáková H. Kusakin A. V. Kušnirák P. Lee H.-J. Molotov I. E. Moon H.-K. Mykhailova S. S. Nikolenko I. V. Novichonok A. Oey J. Omarov Ch. T. Pollock J. T. Reva I. V. Rumyantsev V. V. Astronomy & Astrophysics 657 A5 2110.06548 2022A&A...657A...5D 238744034 1 Spin axis Several lightcurve were also modeled from the abundant photometric observations. In 1994 and 1995, Polish astronomers obtained a concurring period 5.223328 hours and found a spin axis of (54.0°, −52.0°) in ecliptic coordinates (λ, β) (Q=3/3). Radiometric observations gave a period of 5.223327 hours and a pole of (55.0°, −46.0°). Two other international studies obtained a period of 5.223326 hours and a pole at (56.0°, −47.0°) and (55.0°, −45.0°), respectively (Q=3/3). Shape and structure The light curve shows a high amplitude, indicative of its elongated shape, measuring 5.0×2.0×2.1 kilometers, which corresponds to a mean-diameter of 2.5 km. The interior of the asteroid probably has a rubble-pile structure. The asteroid's high thermal inertia indicates the surface is most likely a mix of fine grains and large rocks and boulders. During the asteroid's close approach to Earth in 1994, a radar study of it was conducted by the Deep Space Network at the Goldstone Observatory, California. The resultant images show Geographos to be the most elongated object in the Solar System. Diameter and albedo According to the observations with the Goldstone Observatory and the space-based surveys carried out by the Infrared Astronomical Satellite IRAS and the NEOWISE mission of the Wide-field Infrared Survey Explorer, Geographos measures between 1.77 and 2.56 kilometers in diameter and its surface has an albedo between 0.26 and 0.3258. The Collaborative Asteroid Lightcurve Link adopts an albedo of 0.26 and a diameter of 2.5 kilometers based on an absolute magnitude of 15.09. Naming This minor planet was named after the National Geographic Society, in recognition of its contribution to astronomy by supporting the National Geographic Society – Palomar Observatory Sky Survey (NGS-POSS), which produced a photographic atlas of the entire northern sky in the 1950s. NGS-POSS was headed by the second discoverer, Rudolph Minkowski. The Greek word el geographos means geographer (from geo– 'Earth' + el graphos 'drawer/writer'). The official 1620 naming citation was published by the Minor Planet Center in August 1956 (M.P.C. 1468). alt=Model recreated from Radar images of Geographos|thumb|Model recreated from Radar images of Geographos Notes lcdb-Hamanowa-2011 Hamanowa (2011): lightcurve plot of (1620) Geographos, by H. & H. Hamanowa at the Hamanowa Astronomical Observatory (D91). Obs. date: 2008-02-10; rotation period 5.22204 hours (0.217585 days) with a brightness amplitude of 1.39 mag. Quality Code of 3. Summary figures at the LCDB References 30em 2017-01-11 last obs. JPL Small-Body Database Browser: 1620 Geographos (1951 RA) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001620 Jet Propulsion Laboratory 5 September 2017 Dictionary of Minor Planet Names – (1620) Geographos Schmadel Lutz D. Springer Berlin Heidelberg 128 2007 978-3-540-00238-3 10.1007/978-3-540-29925-7_1621 (1620) Geographos 1620 Geographos (1951 RA) Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=1620 5 September 2017 Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008) 2009 https://archive.org/details/dictionaryminorp2008schm limited Appendix – Publication Dates of the MPCs Schmadel Lutz D. Springer Berlin Heidelberg 221 978-3-642-01964-7 10.1007/978-3-642-01965-4 Asteroids and comets rotation curves – (1620) Geographos Behrend Raoul Geneva Observatory http://obswww.unige.ch/~behrend/page4cou.html#001620 5 September 2017 1 April 2019 https://web.archive.org/web/20190401181659/http://obswww.unige.ch/~behrend/page4cou.html#001620 dead B. Rozitis S. F. Green August 2014 Physical characterisation of near-Earth asteroid (1620) Geographos. Reconciling radar and thermal-infrared observations Astronomy and Astrophysics 568 11 2014A&A...568A..43R 10.1051/0004-6361/201323090 free 1407.2127 9257094 1620 5 September 2017 Harris, Alan W. February 1998 A Thermal Model for Near-Earth Asteroids http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=1998Icar..131..291H Icarus 131 2 291–301 1998Icar..131..291H 10.1006/icar.1997.5865 5 September 2017 R. S. Hudson S. J. 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Price October 2004 IRAS Minor Planet Survey V6.0 https://sbnarchive.psi.edu/pds3/iras/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0 2004PDSS...12.....T 17 October 2019 Dunlap, J. L. February 1974 Minor planets and related objects. XV. Asteroid (1620) Geographos Astronomical Journal 79 324 1974AJ.....79..324D 10.1086/111546 free T. Michalowski T. Kwiatkowski W. Borczyk W. Pych April 1994 CCD Photometry of the Asteroid 1620 Geographos http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=1994AcA....44..223M Acta Astronomica 44 223–226 1994AcA....44..223M 5 September 2017 Kwiatkowski, T. February 1995 Sidereal period, pole and shape of asteroid 1620 Geographos. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=1995A&A...294..274K Astronomy and Astrophysics 294 274–277 1995A&A...294..274K 5 September 2017 6 P. Magnusson M. Dahlgren M. A. Barucci L. Jorda R. P. Binzel S. M. Slivan C. Blanco D. Riccioli B. J. Buratti F. Colas J. 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Tonry Christopher Waters November 2015 Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015Icar..261...34V Icarus 261 34–47 2015Icar..261...34V 10.1016/j.icarus.2015.08.007 1506.00762 53493339 5 September 2017 C. L. Dandy A. Fitzsimmons S. J. Collander-Brown June 2003 Optical colors of 56 near-Earth objects: trends with size and orbit http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2003Icar..163..363D Icarus 163 2 363–373 2003Icar..163..363D 10.1016/S0019-1035(03)00087-3 5 September 2017 6 Steven J. Ostro Raymond F. Jurgens Keith D. Rosema R. Scott Hudson Jon D. Giorgini Ron Winkler Donald K. Yeomans Dennis Choate Randy Rose Martin A. Slade S. Denise Howard Daniel J. Scheeres David L. Mitchell May 1996 Radar Observations of Asteroid 1620 Geographos http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=1996Icar..121...46O Icarus 121 1 46–66 1996Icar..121...46O 10.1006/icar.1996.0071 5 September 2017 External links NASA Asteroid Radar Research - Radar-Detected Asteroids: 1620 Geographos Large amplitude fast rotatorJanuary 2025 medicmedic (Yahoo Groups) Asteroid Lightcurve Database (LCDB), query form (info https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html 16 December 2017 ) Dictionary of Minor Planet Names, Google books Asteroids and comets rotation curves, CdR https://web.archive.org/web/20241208174218/http://obswww.unige.ch/~behrend/page_cou.html 8 December 2024 – Observatoire de Genève, Raoul Behrend 1620 1620 Geographos 1619 Ueta 1620 1621 Druzhba 001620 Category:Discoveries by Albert George Wilson Category:Named minor planets 001620 001620 001620 001620 19510914 Category:Discoveries by Rudolph Minkowski