Astronomy:2015 TB145

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Short description: Asteroid


2015 TB145
Skull2015-TB145.jpg
Radar image of 2015 TB145 taken by the Arecibo Observatory on 30 October 2015.
Discovery[1]
Discovered byPan-STARRS
Discovery date10 October 2015
Designations
2015 TB145
Minor planet category
Orbital characteristics[2]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc3.11 yr (1,137 d)
|{{{apsis}}}|helion}}3.9073 AU
|{{{apsis}}}|helion}}0.2941 AU
2.1007 AU
Eccentricity0.86002
Orbital period3.04 yr (1,112.1 d)
Mean anomaly121.744°
Mean motion0° 19m 25.364s / day
Inclination39.6899°
Longitude of ascending node37.698°
121.744°
Earth MOID0.00295731 AU (442,407 km)
Jupiter MOID2.41052 AU
TJupiter2.97
Physical characteristics
Dimensions
Rotation period
Geometric albedo0.06[5]
Absolute magnitude (H)20.0[2][6]


2015 TB145 is a sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 650 meters (2,000 feet) in diameter.[3] It safely passed 1.27 lunar distances from Earth on 31 October 2015 at 17:01 UTC,[7] and passed by Earth again in November 2018.

Discovery

Discovery image of 2015 TB145 from the Pan-STARRS1 telescope, operated by the Institute for Astronomy at the University of Hawaii.

The asteroid was first observed on 10 October 2015 by Pan-STARRS at an apparent magnitude of 20 using a 1.8-meter (71 in) Ritchey–Chrétien telescope.[1][6][lower-alpha 1] The asteroid was not discovered sooner because it spends most of its time beyond the orbit of Mars, has a large orbital inclination, and is usually well below the plane of the ecliptic.[9] The asteroid last passed within 0.064 astronomical unit|AU (9,600,000 km; 5,900,000 mi) of Earth on 29 October 1923 and will not pass that close again until 1 November 2088.[7]

The media has nicknamed the asteroid the "Great Pumpkin"[10] after the animated Halloween television special It's the Great Pumpkin, Charlie Brown,[11] "Spooky",[12] the "Halloween Asteroid",[13][14] and the "Skull Asteroid"[11] due to its skull-like appearance following radio frequency images taken at Arecibo Observatory and closest approach coincidentally occurring on Halloween day.[11]

2015 flyby

2015 TB145 passed 1.27 LD from the earth, and 0.75 LD from the moon.

On 31 October 2015 the asteroid passed 0.00191 astronomical unit|AU (286,000 km; 178,000 mi) from the Moon and then passed 0.00325 AU (486,000 km; 302,000 mi) from Earth.[7]

The last approach this close by an object with absolute magnitude brighter than 20 was 2004 XP14 on 3 July 2006 at 1.1 lunar distances. The next object this large known to pass this close to Earth is (137108) 1999 AN10 that will pass about 1 lunar distance from Earth on 7 August 2027.[15] It is estimated that there are about 2400 near-Earth asteroids 300–500 meters in diameter, of which about 1100 have been discovered.[16]

During closest approach to Earth the asteroid reached about apparent magnitude 10,[17] which is much too faint to be seen by the naked eye. Even at peak brightness, the asteroid was a challenging target for amateur astronomers with small telescopes, best seen in the Northern hemisphere. The glare from an 80% waning gibbous Moon also hindered observations.[citation needed]

At 11:00 UT the asteroid was in the constellation of Taurus about 9 degrees from the Moon and moving at a rate of 3.4 degrees per hour.[17] At the time of closest approach of 17:00 UT the asteroid was in the constellation of Ursa Major about 56 degrees from the Moon and moving at a rate of 14.7 degrees per hour.[17] After closest approach it quickly became too faint and too close to the Sun in the sky to be seen.[15]

2015 TB145 skypath.png


2018 flyby

Orbit of 2015 TB145

After it had been unobservable for almost three years, 2015 TB145 was recovered on 7 October 2018 by L. Buzzi at Schiaparelli Observatory (observatory code 204), at apparent magnitude 21.[18]

The 11 November 2018 flyby was about 0.267 astronomical unit|AU (39,900,000 km; 24,800,000 mi) from Earth.[7][19]

Observations

Radar imagery

The close approach was studied with radar using Goldstone, the Green Bank Telescope,[15] and the Arecibo Observatory. It was one of the best radar targets of the year with a resolution as high as 2 meters (7 ft) per pixel.[15] Bistatic radar images created with the Green Bank Telescope had a resolution of 4 meters (13 ft) per pixel.[20] Arecibo images had a resolution of 7.5 meters (25 ft) per pixel.[5]

30 October 31 October
12:55–13:08 UTC 		1 November
PIA20041-Asteroid-2015TB145-Animation-20151030.gif Halloween asteroid rotation animation.gif File:2015TB145 November 1.webm

Possible cometary origin

The high orbital inclination and eccentricity suggest 2015 TB145 may be an extinct comet that has shed its volatiles after numerous passes around the Sun.[5][21] Orbital calculations by Petrus Jenniskens and Jérémie Vaubaillon showed that it was not expected to produce associated meteors in 2015.[22] Any meteoroids were expected to pass more than 0.0007 AU (100,000 km; 65,000 mi) from Earth's orbit.[22]

If meteoroids related to this asteroid were to cross Earth's path, the radiant is expected to be near Northern Eridanus.[22] Cameras for Allsky Meteor Surveillance (CAMS) did not detect any activity in the presumed area of the sky during 2013 and 2014.[22] The object has a low albedo of 0.06, which is only slightly more than a typical comet that has an albedo of 0.03-0.05.[5]

Notes

  1. ↑ For comparison, around 6 October 2012, the asteroid peaked at about apparent magnitude 20.9, but had a solar elongation of only about 75 degrees while 0.4 AU from Earth.[8]

References

  1. ↑ 1.0 1.1 "MPEC 2015-T86: 2015 TB145". IAU Minor Planet Center. 2015-10-13. http://www.minorplanetcenter.net/mpec/K15/K15T86.html.  (K15TE5B)
  2. ↑ 2.0 2.1 2.2 2.3 "JPL Small-Body Database Browser: (2015 TB145)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=3729835. 
  3. ↑ 3.0 3.1 Müller, T. G.; Marciniak, A.; Butkiewicz-Bąk, M.; Duffard, R.; Oszkiewicz, D.; Käufl, H. U.; Szakáts, R.; Santana-Ros, T. et al. (February 2017). "Large Halloween asteroid at lunar distance". Astronomy & Astrophysics 598: A63. doi:10.1051/0004-6361/201629584. Bibcode: 2017A&A...598A..63M. https://www.aanda.org/articles/aa/pdf/2017/02/aa29584-16.pdf. Retrieved 13 October 2018. 
  4. ↑ "Asteroid Size Estimator". CNEOS NASA/JPL. https://cneos.jpl.nasa.gov/tools/ast_size_est.html. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Halloween Skies to Include Dead Comet Flyby. NASA-JPL press release. 30 October 2015
  6. ↑ 6.0 6.1 "2015 TB145 Orbit". IAU Minor Planet Center. http://www.minorplanetcenter.net/db_search/show_object?object_id=2015+TB145. 
  7. ↑ 7.0 7.1 7.2 7.3 "JPL Close-Approach Data: (2015 TB145)". https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2015TB145;cad=1#cad. 
  8. ↑ "2015TB145 Ephemerides for October 2012". NEODyS (Near Earth Objects – Dynamic Site). http://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2015TB145&oc=500&y0=2012&m0=10&d0=1&h0=0&mi0=0&y1=2012&m1=10&d1=15&h1=17&mi1=36&ti=1.0&tiu=days. 
  9. ↑ Kelly Beatty (2015-10-22). "Close-in Asteroid Offers Halloween Treat". Sky & Telescope. http://www.skyandtelescope.com/astronomy-news/observing-news/close-in-asteroid-halloween-treat-102220155/. 
  10. ↑ Sarah Begley (30 October 2015). "NASA Says 'Great Pumpkin' Asteroid Will Fly by on Halloween". TIME Magazine. http://time.com/4094227/nasa-great-pumpkin-asteroid/. 
  11. ↑ 11.0 11.1 11.2 Nick Divito (31 October 2015). "Spooky 'skull asteroid' whizzes past Earth on Halloween". New York Post. https://nypost.com/2015/10/31/spooky-skull-asteroid-whizzes-past-earth-on-halloween/. 
  12. ↑ Andrew Fazekas (23 October 2015). "Asteroid Called 'Spooky' Will Buzz Earth on Halloween". National Geographic Society. http://news.nationalgeographic.com/2015/10/151023-astronomy-asteroid-encounter-Earth-stargazing-nasa/. 
  13. ↑ Koren, Marina (31 October 2015). "A Halloween Comet". The Atlantic. https://www.theatlantic.com/science/archive/2015/10/its-dead/413518/. 
  14. ↑ ESA (28 October 2015). "Halloween Asteroid Gives us a Miss, Confirms ESA". European Space Agency. http://www.esa.int/Our_Activities/Operations/Space_Situational_Awareness/Halloween_asteroid_gives_us_a_miss_confirms_ESA. 
  15. ↑ 15.0 15.1 15.2 15.3 Lance A. M. Benner (24 October 2015). "Goldstone Radar Observations Planning: 2009 FD and 2015 TB145". NASA/JPL Asteroid Radar Research. http://echo.jpl.nasa.gov/asteroids/2009FD/2009FD_planning.html. 
  16. ↑ "WISE Revises Numbers of Asteroids Near Earth". NASA/JPL. 2011-09-29. http://www.nasa.gov/mission_pages/WISE/multimedia/gallery/neowise/pia14734.html.  (NASA Space Telescope Finds Fewer Asteroids Near Earth)
  17. ↑ 17.0 17.1 17.2 "2015TB145 Ephemerides for 15 October 2015 through 31 October 2015". NEODyS (Near Earth Objects – Dynamic Site). http://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2015TB145&oc=500&y0=2015&m0=10&d0=15&h0=0&mi0=0&y1=2015&m1=11&d1=1&h1=0&mi1=0&ti=1.0&tiu=hours. 
  18. ↑ "MPEC 2018-T130: 2015 TB145". Minor Planet Center. 10 October 2018. https://minorplanetcenter.net/mpec/K18/K18TD0.html. 
  19. ↑ Williams, Matt (1 October 2018). "The "Death Comet" Will Pass By Earth Just After Halloween". Universe Today. https://www.universetoday.com/140108/the-death-comet-will-pass-by-earth-just-after-halloween/. 
  20. ↑ "PIA20043: Halloween Asteroid Rotation". NASA/JPL-Caltech/GSSR/NRAO/GB. 2015-11-03. http://photojournal.jpl.nasa.gov/catalog/PIA20043. 
  21. ↑ Agle, D. C. (21 October 2015). "NASA Spots the 'Great Pumpkin': Halloween Asteroid a Treat for Radar Astronomers". NASA News. http://www.jpl.nasa.gov/news/news.php?feature=4745. 
  22. ↑ 22.0 22.1 22.2 22.3 "Possible October 31 Meteors From Minor Planet 2015 TB_145". SETI Institute. 2015-10-26. http://www.seti.org/seti-institute/news/possible-october-31-meteors-minor-planet-2015-tb145.  (CBET 4154)

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