2015 TB145

2015 TB145
Discovery[1]
Discovered by Pan-STARRS
Discovery date 10 October 2015
Designations
MPC designation 2015 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 arc 22 days
Aphelion 3.9076 AU (584.57 Gm) (Q)
Perihelion 0.29345 AU (43.899 Gm) (q)
2.1005 AU (314.23 Gm) (a)
Eccentricity 0.86030 (e)
3.04 yr (1112.0 d)
10.4818° (M)
0° 19m 25.5s / day (n)
Inclination 39.6863° (i)
37.7318° (Ω)
121.731° (ω)
Earth MOID 0.00155156 AU (232,110 km)
Jupiter MOID 2.41379 AU (361.098 Gm)
TJupiter 2.964
Physical characteristics
Dimensions 650±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]

    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]

    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 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.[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 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.

    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 KJ91914-12-310.6060.6040.60819.4279–900data
    (458732) 2011 MD51918-09-170.9110.9090.91317.9556–1795data
    (163132) 2002 CU111925-08-300.9030.9010.90518.5443–477data
    69230 Hermes1937-10-301.9261.9261.92717.5700-900[20]data
    69230 Hermes1942-04-261.6511.6511.65117.5700-900[20]data
    (27002) 1998 DV91975-01-311.7621.7611.76218.1507–1637data
    2002 NY402002-08-181.3711.3711.37119.0335–1082data
    2004 XP142006-07-031.1251.1251.12519.3292–942data
    2015 TB1452015-10-311.2661.2661.26620.0620-690data
    (137108) 1999 AN102027-08-071.0141.0101.01917.9556–1793data
    (153814) 2001 WN52028-06-260.6470.6470.64718.2921–943data
    99942 Apophis2029-04-130.09810.09630.100019.7310–340data
    2017 MB12072-07-261.2161.2152.75918.8367–1186data
    2011 SM682072-10-171.8751.8651.88619.6254–820data
    (163132) 2002 CU112080-08-311.6551.6541.65618.5443–477data
    (416801) 1998 MZ2116-11-261.0681.0681.06919.2305–986data
    (153201) 2000 WO1072140-12-010.6340.6310.63719.3427–593data
    (276033) 2002 AJ1292172-02-081.7831.7751.79218.7385–1242data
    (290772) 2005 VC2198-05-051.9511.7912.13417.6638–2061data
    (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 passage

    On 11 November 2018 the asteroid will pass 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]

    Observations

    Radar imagery

    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]

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

    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][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]

    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 0.4AU from Earth.[8]

    References

    1. 1 2 "MPEC 2015-T86 : 2015 TB145". IAU Minor Planet Center. 2015-10-13. Retrieved 2015-10-14. (K15TE5B)
    2. 1 2 3 4 5 "JPL Small-Body Database Browser: (2015 TB145)" (last observation: 2015-10-27; arc: 17 days). Jet Propulsion Laboratory. Retrieved 4 April 2016.
    3. 1 2 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. 1 2 3 4 5 6 Halloween Skies to Include Dead Comet Flyby. NASA-JPL press release. October 30, 2015
    6. 1 2 "2015 TB145 Orbit". IAU Minor Planet Center. Retrieved 2016-01-24.
    7. 1 2 3 4 "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. 1 2 3 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. 1 2 3 4 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. 1 2 3 "2015TB145 Ephemerides for 15 October 2015 through 31 October 2015". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 2015-10-14.
    20. 1 2 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. 1 2 3 4 "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)

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