(415029) 2011 UL21

Apollo-class asteroid October 2019 yes #FFC2E0 (415029) 2011 UL 21 E1 PIA26384 2011ul21.jun27 ALL.jpg Catalina Sky Srvy. Catalina Stn. 17 October 2011 (415029) 2011 UL 21 ApolloNEOPHA 13 January 2016 (JD 2,457,400.5) 0 9,379 days (25.68 yr) 3.5091 AU Gm on 0.73606 AU Gm 2.1226 AU Gm 0.65323 3.09 yr (1129.5 d) 34.845° 275.60° 110.19° 0.31872 ms / day 284.74° 1 moonlet discovered 0.0185982 AU Gm 2.5 km 2.113 kg (assumed) 15.8 (415029) 2011 UL 21 is an Apollo-class potentially hazardous asteroid discovered on 17 October 2011, by the Catalina Sky Survey project. The asteroid is estimated to have a diameter of 2.5 km. It was rated at Torino scale 1 on 27 October 2011, with an observation arc of 9.6 days. 2011 UL 21 is the largest asteroid ever to be rated above a 0 on the Torino scale. Description 2011 UL 21 briefly had about a 1 in a million chance of impacting in 2029. Its cumulative impact probability dropped to 1 in 71 million by 2 November 2011 when the observation arc reached 15 days. It was removed from the Sentry risk table on 4 November 2011 when all impact scenarios for the next 100 years or more were ruled out. During 2029, the closest approach to Earth is 1.6 AU. Palomar Observatory precovery images from 1989 and 1990 have extended the observation arc to 22 years. With an absolute magnitude of 15.8, it is one of the brightest and therefore largest potentially hazardous asteroids (PHA) detected since (242450) 2004 QY 2. The next largest PHA (based on absolute magnitude) discovered in 2011 is 2011 WO 41 with an absolute magnitude of 16.8. On 27 June 2024 it had a relatively close fly-by with the Earth, reaching a minimum distance of 0.044 AU e6km e6mi unit on from it.Masi Gianluca 2024-05-27 The large potentially hazardous asteroid 2011 UL21 is safely approaching, no risk for our Earth - 27 May 2024 https://www.virtualtelescope.eu/2024/05/27/the-large-potentially-hazardous-asteroid-2011-ul21-is-safely-approaching-no-risk-for-our-earth-27-may-2024/ 2024-05-28 The Virtual Telescope Project 2.0 en-US It was revealed to be orbited by a moonlet.Carter Jamie NASA Drops Stunning New Images Of Mile-Wide Asteroid With Its Own Moon https://www.forbes.com/sites/jamiecartereurope/2024/07/03/nasa-drops-stunning-new-images-a-mile-wide-asteroid-with-a-moon/ 2024-07-05 Forbes en 2024-07-03 See also 2024 MK – a near-Earth object that made a close approach on 29 June 2024 References MPEC 2011-U39 : 2011 UL21 IAU Minor Planet Center 2011-10-28 https://www.minorplanetcenter.net/mpec/K11/K11U39.html November 1, 2011 2012-04-18 last obs (arc=22 years) JPL Small-Body Database Browser: (2011 UL21) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2011UL21 Jet Propulsion Laboratory 8 April 2016 Earth Impact Risk Summary: 2011 UL21 NASA/JPL Near-Earth Object Program Office http://neo.jpl.nasa.gov/risk/2011ul21.html November 1, 2011 2 November 2011 https://web.archive.org/web/20111102214142/http://neo.jpl.nasa.gov/risk dead 2011-10-27 Observations of small Solar-System bodies hohmanntransfer http://www.hohmanntransfer.com/mn/11/11300_1027.htm#2011UL21 2013-09-04 29 November 2014 https://web.archive.org/web/20141129025147/http://www.hohmanntransfer.com/mn/11/11300_1027.htm#2011UL21 dead (1.5e-06 = 1 in 667,000 chance) October 26, 2011 Should we be concerned about 2011 UL21 NASA Ask An Astrobiologist Morrison David David Morrison (astrophysicist) https://www.astrobiology.nasa.gov/ask-an-astrobiologist/answered/2011/10/27/2058/ 2011-11-06 June 2021 medicmedic Date/Time Removed NASA/JPL Near-Earth Object Program Office https://cneos.jpl.nasa.gov/sentry/removed.html 2011-11-06 2012 04 18 (arc=22 years) 2011 UL21 Orbit Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=2011+UL21 2012-05-17 2012-04-18 last obs (arc=22 years) JPL Close-Approach Data: (2011 UL21) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2011UL21;cad=1#cad 2012-05-17 JPL Small-Body Database Search Engine: PHAs and H < 17 (mag) JPL Solar System Dynamics https://ssd.jpl.nasa.gov/sbdb_query.cgi?obj_group=pha;obj_kind=all;obj_numbered=all;OBJ_field=0;ORB_field=0;c1_group=OBJ;c1_item=Ai;c1_op=%3C;c1_value=17;table_format=HTML;max_rows=100;format_option=comp;c_fields=AcBhBgBjBiBnBsCkCqAi;.cgifields=format_option;.cgifields=obj_kind;.cgifields=obj_group;.cgifields=obj_numbered;.cgifields=ast_orbit_class;.cgifields=table_format;.cgifields=com_orbit_class&query=1&c_sort=AcA 2011-11-20 External links 415029 415029 2011UL21 415029 (415029) 2011 UL 21 415029 415029 415029 415029 20111017