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2015 TB145

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2015 TB145
Image
Radar image of 2015 TB145 taken by the Arecibo Observatory on 30 October 2015
Discovery[1]
Discovered byPan-STARRS
Discovery date10 October 2015
Designations
Orbital characteristics[2]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc3.11 yr (1,137 d)
Aphelion3.9073 AU
Perihelion0.2941 AU
2.1007 AU
Eccentricity0.86002
3.04 yr (1,112.1 d)
121.744°
0° 19m 25.364s / day
Inclination39.6899°
37.698°
121.744°
Earth MOID0.00295731 AU (442,407 km)
Jupiter MOID2.41052 AU
TJupiter2.97
Physical characteristics
Dimensions
0.06[5]
20.0[2][6]

2015 TB145 is a sub-kilometer asteroid, classified as a 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

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Image
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 is usually 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] 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

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Image
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.[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]

Image

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[18]data
69230 Hermes1942-04-261.6511.6511.65117.5700-900[18]data
2017 NM61959-07-121.891.8461.93418.8580–1300data
(27002) 1998 DV91975-01-311.7621.7611.76218.1507–1637data
2002 NY402002-08-181.3711.3711.37119.0335–1082data
(612901) 2004 XP14142006-07-031.1251.1251.12519.3292–942data
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 flyby

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Image
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.[19]

The 11 November 2018 flyby was about 0.267 AU (39,900,000 km; 24,800,000 mi) from Earth.[7][20]

Observations

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Radar imagery

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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.[21] 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
Image Image

Possible cometary origin

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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][22] Orbital calculations by Petrus Jenniskens and Jérémie Vaubaillon showed that it was not expected to produce associated meteors in 2015.[23] Any meteoroids were expected to pass more than 0.0007 AU (100,000 km; 65,000 mi) from Earth's orbit.[23]

If meteoroids related to this asteroid were to cross Earth's path, the radiant is expected to be near Northern Eridanus.[23] Cameras for Allsky Meteor Surveillance (CAMS) did not detect any activity in the presumed area of the sky during 2013 and 2014.[23] 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

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  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

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  1. 1 2 "MPEC 2015-T86: 2015 TB145". IAU Minor Planet Center. 13 October 2015. Retrieved 14 October 2015. (K15TE5B)
  2. 1 2 3 4 "JPL Small-Body Database Browser: (2015 TB145)" (2018-11-20 last obs.). Jet Propulsion Laboratory. Retrieved 1 March 2020.
  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. Bibcode:2017A&A...598A..63M. doi:10.1051/0004-6361/201629584. S2CID 119162848. 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. 30 October 2015
  6. 1 2 "2015 TB145 Orbit". IAU Minor Planet Center. Retrieved 24 January 2016.
  7. 1 2 3 4 "JPL Close-Approach Data: (2015 TB145)" (last observation: 2015-10-27; arc: 17 days). Retrieved 22 October 2015.
  8. ↑ "2015TB145 Ephemerides for October 2012". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 24 October 2015.
  9. ↑ Kelly Beatty (22 October 2015). "Close-in Asteroid Offers Halloween Treat". Sky & Telescope. Retrieved 26 October 2015.
  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. Archived from the original on 23 October 2015.
  13. ↑ Koren, Marina (31 October 2015). "A Halloween Comet". The Atlantic. Retrieved 1 January 2019.
  14. ↑ ESA (28 October 2015). "Halloween Asteroid Gives us a Miss, Confirms ESA". European Space Agency. Archived from the original on 4 May 2017. Retrieved 2 November 2015.
  15. 1 2 3 4 Lance A. M. Benner (24 October 2015). "Goldstone Radar Observations Planning: 2009 FD and 2015 TB145". NASA/JPL Asteroid Radar Research. Retrieved 24 October 2015.
  16. ↑ "WISE Revises Numbers of Asteroids Near Earth". NASA/JPL. 29 September 2011. Archived from the original on 5 December 2017. Retrieved 29 October 2015. (NASA Space Telescope Finds Fewer Asteroids Near Earth) Archived 12 November 2020 at the Wayback Machine
  17. 1 2 3 "2015TB145 Ephemerides for 15 October 2015 through 31 October 2015". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 14 October 2015.
  18. 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. Bibcode:2012Icar..221.1130M. doi:10.1016/j.icarus.2012.09.013. Retrieved 24 August 2018.
  19. ↑ "MPEC 2018-T130: 2015 TB145". Minor Planet Center. 10 October 2018. Retrieved 13 October 2018.
  20. ↑ Williams, Matt (1 October 2018). "The "Death Comet" Will Pass By Earth Just After Halloween". Universe Today. Retrieved 13 October 2018.
  21. ↑ "PIA20043: Halloween Asteroid Rotation". NASA/JPL-Caltech/GSSR/NRAO/GB. 3 November 2015. Retrieved 4 November 2015.
  22. ↑ Agle, D. C. (21 October 2015). "NASA Spots the 'Great Pumpkin': Halloween Asteroid a Treat for Radar Astronomers". NASA News. Retrieved 26 October 2015.
  23. 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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