2010 WC9

Near-Earth asteroid first observed in 2010 May 2018 yes 2010 WC 9 #FFC2E0 2010_WC9-2018orbit.png Orbit of 2010 WC 9 with positions before 2018 flyby Catalina Sky Srvy. Catalina Stn.(first observed only) 30 November 2010 2010 WC 9 ZJ99C60 NEO Apollo 21 November 2025 (JD 2461000.5) 0 7.46 yr (2,723 d) 1.3727 AU 0.7652 AU 1.0689 AU 0.2841 1.11 yr (404 d) 225.55° 0.8918 ms / day 17.681° 54.598° 275.96° 0.00000867 AU (0.00338 LD) 0.14214 AU km on off 60 - 130 m 60 m (est. at 0.20) 130 m (est. at 0.04) 0.18469 hours 23.66 2010 WC 9 is a sub-kilometer near-Earth asteroid of the Apollo group, approximately 100 m off us in diameter. First observed for eleven days by the Catalina Sky Survey in 2010, the asteroid was recovered in May 2018 during its sub-lunar close encounter with Earth. First observation and recovery 2010 WC 9 was first observed by astronomers with the Catalina Sky Survey on 30 November 2010 with a 1-day observation arc and was observed through 10 December 2010. By 10 December 2010, the asteroid was more than 24 million kilometers from Earth at apparent magnitude 21.8 and was becoming too faint to be practical to track. The preliminary 10-day observation arc generated a line of variation roughly 15 million km long for May 2018 that did not intersect Earth's orbit and thus was not a 2018 impact threat. The 10-day observation arc showed the asteroid would pass about 0.026 AU km mi on on from Earth around late 14 May 2018. The asteroid was recovered on 8 May 2018 when it was 8 million kilometers from Earth and given the temporary NEOCP designation ZJ99C60. It was removed from the Sentry Risk Table on 10 May 2018 and is not an impact threat for the next 100 years or more. The asteroid now has a secure 7-year observation arc. Orbit and classification 2010 WC 9 is an Apollo asteroid, the largest dynamical group of near-Earth objects with nearly 10,000 known members. It orbits the Sun at a distance of 0.77–1.37 AU once every 13 months (404 days; semi-major axis of 1.07 AU). Its orbit has an eccentricity of 0.28 and an inclination of 18° with respect to the ecliptic. Using an epoch of 21 November 2025, the object had a minimum orbital intersection distance with Earth of 0.00000867 AU km on off 3 flip, or 0.00338 lunar distances (LD). 2018 approach On 15 May 2018, 22:05 UT, the asteroid approached Earth at just over 0.5 LD, the closest approach of this asteroid in nearly 300 years. It was expected to reach apparent magnitude +11 at closest approach, bright enough to be seen in a small telescope if you have a custom ephemeris for your location. At closest approach, it was best seen from the Southern hemisphere such as South Africa and southern South America. The asteroid passed Earth going 12.81 km/s mph on. This was the third closest approach ever observed by an asteroid with absolute magnitude (H) brighter than 24. horizontal left 225 2010_WC9-2018sky.png 2010_WC9-2018flyby.png Flyby in 2018: geocentric trajectory in the sky (top) and flyby from north to south, shown with hourly motion (bottom) left horizontal 300 Animation of 2010 WC9's orbit Animation of 2010 WC9 orbit around Sun.gif Around the Sun Animation of 2010 WC9 orbit around Earth.gif Around the Earth magenta 2010 WC9Yellow SunRoyalblue Earthgold Moon Physical characteristics Diameter As the asteroid has not been directly resolved by telescope, its diameter can only be estimated based on the distance and brightness. Based on a generic magnitude-to-diameter conversion, it is estimated to measure between 60 and 130 meters in diameter, for an absolute magnitude of 23.5, and an assumed albedo of 0.04–0.20. Numbering and naming As of 2018, this minor planet has neither been numbered nor named by the Minor Planet Center. See also List of asteroid close approaches to Earth in 2018 References 30em 2018-05-15 last obs. JPL Small-Body Database Browser: (2010 WC9) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=3552664 Jet Propulsion Laboratory 11 May 2018 https://web.archive.org/web/20180510124328/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2010WC9;cad=1 10 May 2018 live 2010 WC9 Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=2010+WC9 11 May 2018 MPEC 2010-X07 : 2010 WC9 IAU Minor Planet Center 2010-12-01 https://minorplanetcenter.net/mpec/K10/K10X07.html 2018-05-13 (K10W09C) MPC/MPO/MPS Archive: MPS 358671-362682 IAU Minor Planet Center 2010-12-19 https://www.minorplanetcenter.net/iau/ECS/MPCArchive/2010/MPS_20101219.pdf 2018-05-13 (pg 645) Earth Impact Risk Summary: 2010 WC9 (10 day arc; computed on Sep 20, 2015) http://neo.jpl.nasa.gov/risk/2010wc9.html 2010 WC9 Impact Risk 13 May 2018 https://web.archive.org/web/20161215233547/http://neo.jpl.nasa.gov/risk/2010wc9.html 15 December 2016 dead Removed Objects https://cneos.jpl.nasa.gov/sentry/removed.html Sentry: Earth Impact Monitoring 14 May 2018 https://web.archive.org/web/20180513185518/https://cneos.jpl.nasa.gov/sentry/removed.html 13 May 2018 bot: unknown 2010WC9 Ephemerides for 15–16 May 2018 NEODyS (Near Earth Objects Dynamic Site) https://newton.spacedys.com/neodys2/index.php?pc=1.1.3.1&n=2010WC9&oc=500&y0=2018&m0=5&d0=15&h0=0&mi0=0&y1=2018&m1=5&d1=17&h1=0&mi1=0&ti=1.0&tiu=hours 2018-05-14 "Lost" asteroid to pass closely May 15 Eddie Irizarry earthsky.org 12 May 2018 https://earthsky.org/space/lost-asteroid-to-pass-closely-may-15 12 May 2018 Asteroid Size Estimator CNEOS NASA/JPL https://cneos.jpl.nasa.gov/tools/ast_size_est.html 14 May 2018 Closest Approaches to the Earth by Minor Planets Minor Planet Center https://www.minorplanetcenter.net/iau/lists/Closest.html 14 May 2018 "Pseudo-MPEC" for ZJ99C60 projectpluto.com 10 May 2018 https://www.projectpluto.com/neocp2/mpecs/ZJ99C60.htm 14 May 2018 https://web.archive.org/web/20180512044316/https://www.projectpluto.com/neocp2/mpecs/ZJ99C60.htm 12 May 2018 dead External links "Lost" asteroid to pass closely May 15 Eddie Irizarry, 12 May 2018 Asteroid 2010 WC9 to flyby Earth at 0.53 LD on 15 May List Of Apollo Minor Planets (by designation), Minor Planet Center 2010WC9 2010WC9 3552664 # Category:Minor planet object articles (unnumbered) # # 20180515 20101130