2009 SH2

Near-Earth asteroid February 2021 yes 2009 SH 2 #FFC2E0 Siding Spring Survey Siding Spring Obs. 18 September 2009 2009 SH 2 Earth co-orbitalNEOAten 21 November 2025 (JD 2461000.5) 4 14 days 1.085 AU 0.8978 AU 21 October 2025 05:40 UT 0.991 AU 0.09423 0.99 yr (360.47 d) 30.7234° 0.9986873 ms / day 6.810° 6.657° 101.752° 0.0002 AU km 30 - 60 m (assumed albedo 0.05–0.25) 1.26 h 18.8 (at discovery) 24.9 2009 SH 2 is a sub-kilometer near-Earth asteroid of the Aten group, discovered by the Siding Spring Survey at Siding Spring Observatory, Australia on 18 September 2009. It is in a co-orbital configuration with Earth, a type of 1:1 orbital resonance where the asteroid appears to librate around Earth's path in a horseshoe orbit when viewed in a corotating reference frame with Earth. The co-orbital state of 2009 SH 2 is only temporary as it has entered it about 30 years ago and will leave it in about 100 years into the future. Discovery 2009 SH 2 was discovered by the Siding Spring Survey at Siding Spring Observatory, Coonabarabran, New South Wales, Australia on 18 September 2009. It was first observed in the constellation Fornax at an apparent magnitude of 18.8. The asteroid was moving at an on-sky rate around 2.5 arcseconds per minute, from a distance of 0.030 AU e6km e6mi unit from Earth. Follow-up observations of the asteroid were carried out by the Rio Cuarto Observatory (I20) on the following day. The asteroid was then confirmed by the Minor Planet Center and announced as 2009 SH 2 on 19 September 2009. Orbit thumb|left|Orbit diagram of 2009 SH 2 and the inner planets 2009 SH 2 orbits the Sun at an average distance of 0.99 AU once every 360 days, or approximately 0.99 years. Its orbit has an eccentricity of 0.09 and an inclination of 7° with respect to the ecliptic plane. Over the course of its orbit, its distance from the Sun ranges from 0.90 AU at perihelion to 1.08 AU at aphelion, crossing the orbit of Earth. Since its orbit crosses that of Earth's while having a semi-major axis less than 1 AU, 2009 SH 2 is classified as an Aten asteroid. Its nominal orbit has a small minimum orbit intersection distance approximately 0.0006 AU km mi from Earth's orbital path and periodically makes close approaches to Earth. In 2013, astronomers Carlos and Raúl de la Fuente Marcos identified 2009 SH 2 to be in a co-orbital configuration with Earth, a type of 1:1 orbital resonance where the asteroid appears to librate around Earth's path in a horseshoe orbit when viewed in a corotating reference frame with Earth. The co-orbital state of 2009 SH 2 is only temporary as it has entered it about 30 years ago and will leave it in about 100 years into the future. Physical characteristics Based on a magnitude-to-diameter conversion and a measured absolute magnitude of 24.9, 2009 SH 2 measures between 30 and 60 meters in diameter for an assumed geometric albedo of 0.25 and 0.05, respectively. A rotation period of 1.26 h has been tentatively measured from its lightcurve. See also Arjuna asteroid 2003 YN 107 2006 JY 26 2012 FC 71 2013 BS 45 References 2009-10-02 last obs. JPL Small-Body Database Browser: 2009 SH2 https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=3467258 Jet Propulsion Laboratory 12 February 2021 2009 SH2 http://www.minorplanetcenter.net/db_search/show_object?object_id=2009+SH2 Minor Planet Center International Astronomical Union 12 February 2021 Ephemerides at discovery (obs. code E12) 2009SH2 Ephemerides https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2009SH2&oc=E12&y0=2009&m0=9&d0=18&h0=18&mi0=0&y1=2009&m1=9&d1=18&h1=19&mi1=0&ti=10&tiu=minutes Near Earth Objects – Dynamic Site Department of Mathematics, University of Pisa, Italy 12 February 2021 MPEC 2009-S51 : 2009 SH2 https://minorplanetcenter.net/mpec/K09/K09S51.html Minor Planet Electronic Circular Minor Planet Center 19 September 2009 12 February 2021 Conversion of Absolute Magnitude to Diameter for Minor Planets http://www.physics.sfasu.edu/astro/asteroids/sizemagnitude.html Dan Bruton Department of Physics, Engineering, and Astronomy Stephen F. Austin State University 12 February 2021 23 July 2011 https://web.archive.org/web/20110723191750/http://www.physics.sfasu.edu/astro/asteroids/sizemagnitude.html dead C. de la Fuente Marcos R. de la Fuente Marcos A resonant family of dynamically cold small bodies in the near-Earth asteroid belt September 2013 Monthly Notices of the Royal Astronomical Society: Letters 434 1 L1–L5 10.1093/mnrasl/slt062 free 1305.2825 2013MNRAS.434L...1D External links 2009sh2 2009SH2 3467258 Astronomy Outer Space # # Category:Minor planet object articles (unnumbered) # Category:Earth-crossing asteroids 20090918