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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 will pass by Earth again in November 2018. The asteroid has not been observed since 2015.[2]

2015 TB145
2015 TB145 orbit 2015.png
Discovery[1]
Discovered byPan-STARRS
Discovery date10 October 2015
Designations
MPC designation2015 TB145
Apollo, NEO, PHA,
Mercury-crosser asteroid,
Venus-crosser asteroid,
Mars-crosser asteroid[2]
Orbital characteristics[2]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 2
Observation arc22 days
Aphelion3.9076 AU (584.57 Gm) (Q)
Perihelion0.29345 AU (43.899 Gm) (q)
2.1005 AU (314.23 Gm) (a)
Eccentricity0.86030 (e)
3.04 yr (1112.0 d)
10.4818° (M)
0° 19m 25.5s / day (n)
Inclination39.6863° (i)
37.7318° (Ω)
121.731° (ω)
Earth MOID0.00155156 AU (232,110 km)
Jupiter MOID2.41379 AU (361.098 Gm)
TJupiter2.964
Physical characteristics
Dimensions650±30 m (2130±100 ft)[3]
600 m[4][5]
5 hours,[5] 2.938 h (0.1224 d)[2]
0.06[5]
20.0[2][6]

Contents

DiscoveryEdit

 
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][a] The asteroid was not discovered sooner because it spends most of its time beyond the orbit of Mars, has a large orbital inclination, and spends most of its time well below the plane of the ecliptic.[9] The asteroid last passed within 0.064 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][13] the "Halloween Asteroid",[14][15][16] and the "Skull Asteroid"[11] due to its human skull-like appearance following radio frequency images taken at Arecibo Observatory and closest approach coincidentally occurring on Halloween day.[11]

2015 flybyEdit

 
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 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.[17] It is estimated that there are about 2400 near-Earth asteroids 300–500 meters in diameter, of which about 1100 have been discovered.[18]

During closest approach to Earth the asteroid reached about apparent magnitude 10,[19] 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.[19] 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.[19] After closest approach it quickly became too faint and too close to the Sun in the sky to be seen.[17]

 

History of close approaches of large near-Earth objects since 1908 (A)
PHA Date Approach distance in lunar distances Abs. mag
(H)
Diameter (C)
(m)
Ref (D)
Nominal(B) Minimum Maximum
(152680) 1998 KJ9 1914-12-31 0.606 0.604 0.608 19.4 279–900 data
(458732) 2011 MD5 1918-09-17 0.911 0.909 0.913 17.9 556–1795 data
(163132) 2002 CU11 1925-08-30 0.903 0.901 0.905 18.5 443–477 data
69230 Hermes 1937-10-30 1.926 1.926 1.927 17.5 700-900[20] data
69230 Hermes 1942-04-26 1.651 1.651 1.651 17.5 700-900[20] data
(27002) 1998 DV9 1975-01-31 1.762 1.761 1.762 18.1 507–1637 data
2002 NY40 2002-08-18 1.371 1.371 1.371 19.0 335–1082 data
2004 XP14 2006-07-03 1.125 1.125 1.125 19.3 292–942 data
2015 TB145 2015-10-31 1.266 1.266 1.266 20.0 620-690 data
(137108) 1999 AN10 2027-08-07 1.014 1.010 1.019 17.9 556–1793 data
(153814) 2001 WN5 2028-06-26 0.647 0.647 0.647 18.2 921–943 data
99942 Apophis 2029-04-13 0.0981 0.0963 0.1000 19.7 310–340 data
2017 MB1 2072-07-26 1.216 1.215 2.759 18.8 367–1186 data
2011 SM68 2072-10-17 1.875 1.865 1.886 19.6 254–820 data
(163132) 2002 CU11 2080-08-31 1.655 1.654 1.656 18.5 443–477 data
(416801) 1998 MZ 2116-11-26 1.068 1.068 1.069 19.2 305–986 data
(153201) 2000 WO107 2140-12-01 0.634 0.631 0.637 19.3 427–593 data
(276033) 2002 AJ129 2172-02-08 1.783 1.775 1.792 18.7 385–1242 data
(290772) 2005 VC 2198-05-05 1.951 1.791 2.134 17.6 638–2061 data
(A) This list includes near-Earth approaches of less than 2 lunar distances (LD) of objects with H brighter than 20.
(B) Nominal geocentric distance from the center of Earth to the center of the object (Earth has a radius of approximately 6,400 km).
(C) Diameter: estimated, theoretical mean-diameter based on H and albedo range between X and Y.
(D) Reference: data source from the JPL SBDB, with AU converted into LD (1 AU≈390 LD)
(E) Color codes:   unobserved at close approach   observed during close approach   upcoming approaches

2018 flybyEdit

On 11 November 2018 the flyby about 0.27 AU (40,000,000 km; 25,000,000 mi) from Earth.[7] It will only brighten to magnitude 19.[21]

After it had been unobservable for almost three years, 2015 TB145 has been recovered on 7 October 2018 by L. Buzzi at Schiaparelli Observatory, at apparent magnitude 21.[22]

ObservationsEdit

Radar imageryEdit

The close approach was studied with radar using Goldstone, the Green Bank Telescope,[17] 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.[17] Bistatic radar images created with the Green Bank Telescope had a resolution of 4 meters (13 ft) per pixel.[23] Arecibo images had a resolution of 7.5 meters (25 ft) per pixel.[5]

30 October October 31
12:55 - 13:08 UTC
1 November
   

Possible cometary originEdit

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][24] Orbital calculations by Petrus Jenniskens and Jérémie Vaubaillon showed that it was not expected to produce associated meteors in 2015.[25] Any meteoroids were expected to pass more than 0.0007 AU (100,000 km; 65,000 mi) from Earth's orbit.[25] If meteoroids related to this asteroid were to cross Earth's path, the radiant is expected to be near Northern Eridanus.[25] Cameras for Allsky Meteor Surveillance (CAMS) did not detect any activity in the presumed area of the sky during 2013 and 2014.[25] 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]

NotesEdit

  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 0.4AU from Earth.[8]

ReferencesEdit

  1. ^ a b "MPEC 2015-T86 : 2015 TB145". IAU Minor Planet Center. 2015-10-13. Retrieved 2015-10-14. (K15TE5B)
  2. ^ a b c d e "JPL Small-Body Database Browser: (2015 TB145)" (last observation: 2015-10-27; arc: 17 days). Jet Propulsion Laboratory. Retrieved 4 April 2016.
  3. ^ a b Müller, T. G.; Marciniak, A.; Butkiewicz-Bąk, M.; Duffard, R.; Oszkiewicz, D.; Käufl, H. U.; Szakáts, R.; Santana-Ros, T.; Kiss, C.; Santos-Sanz, P. (February 2017). "Large Halloween asteroid at lunar distance" (PDF). Astronomy & Astrophysics. 598: A63. arXiv:1610.08267. doi:10.1051/0004-6361/201629584. Retrieved 13 October 2018.
  4. ^ "Asteroid Size Estimator". CNEOS NASA/JPL. Retrieved 16 February 2018.
  5. ^ a b c d e f Halloween Skies to Include Dead Comet Flyby. NASA-JPL press release. 30 October 2015
  6. ^ a b "2015 TB145 Orbit". IAU Minor Planet Center. Retrieved 2016-01-24.
  7. ^ a b c d "JPL Close-Approach Data: (2015 TB145)" (last observation: 2015-10-27; arc: 17 days). Retrieved 2015-10-22.
  8. ^ "2015TB145 Ephemerides for October 2012". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 2015-10-24.
  9. ^ Kelly Beatty (2015-10-22). "Close-in Asteroid Offers Halloween Treat". Sky & Telescope. Retrieved 2015-10-26.
  10. ^ Sarah Begley (30 October 2015). "NASA Says 'Great Pumpkin' Asteroid Will Fly by on Halloween". TIME Magazine.
  11. ^ a b c Nick Divito (31 October 2015). "Spooky 'skull asteroid' whizzes past Earth on Halloween". New York Post.
  12. ^ Andrew Fazekas (23 October 2015). "Asteroid Called 'Spooky' Will Buzz Earth on Halloween". National Geographic Society.
  13. ^ RT (31 October 2015). "'Spooky' asteroid to fly by Earth on Halloween". RT (Russia Today).
  14. ^ Charles Poladian (20 October 2015). "Halloween Asteroid 2015 TB145 Hurtling Toward Earth At 80,000 MPH: Doomsday Threat?". International Business Times.
  15. ^ Morina Koren (31 October 2015). "A Halloween Comet". The Atlantic.
  16. ^ ESA (28 October 2015). "Halloween Asteroid Gives us a Miss, Confirms ESA". European Space Agency.
  17. ^ a b c d Dr. Lance A. M. Benner (24 October 2015). "Goldstone Radar Observations Planning: 2009 FD and 2015 TB145". NASA/JPL Asteroid Radar Research. Retrieved 2015-10-24.
  18. ^ "WISE Revises Numbers of Asteroids Near Earth". NASA/JPL. 2011-09-29. Retrieved 2015-10-29. (NASA Space Telescope Finds Fewer Asteroids Near Earth)
  19. ^ a b c "2015TB145 Ephemerides for 15 October 2015 through 31 October 2015". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 2015-10-14.
  20. ^ a b Marchis, F.; et al. "Multiple asteroid systems: Dimensions and thermal properties from Spitzer Space Telescope and ground-based observations". Icarus. 221 (2): 1130–1161. Retrieved 24 August 2018.
  21. ^ Williams, Matt (1 October 2018). "The "Death Comet" Will Pass By Earth Just After Halloween". Universe Today. Retrieved 13 October 2018.
  22. ^ "MPEC 2018-T130: 2015 TB145". Minor Planet Center. 10 October 2018. Retrieved 13 October 2018.
  23. ^ "PIA20043: Halloween Asteroid Rotation". NASA/JPL-Caltech/GSSR/NRAO/GB. 2015-11-03. Retrieved 2015-11-04.
  24. ^ Agle, D. C. (21 October 2015). "NASA Spots the 'Great Pumpkin': Halloween Asteroid a Treat for Radar Astronomers". NASA News. Retrieved 2015-10-26.
  25. ^ a b c d "Possible October 31 Meteors From Minor Planet 2015 TB_145". SETI Institute. 26 October 2015. Archived from the original on 28 October 2015. Retrieved 26 October 2015. (CBET 4154)

External linksEdit