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2015 TB145
Radar image of 2015 TB145 taken by the Arecibo Observatory on 30 October 2015.
Discovery [1]
Discovered by Pan-STARRS
Discovery date10 October 2015
Designations
2015 TB145
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 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] [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

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]

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 [18] data
69230 Hermes 1942-04-26 1.651 1.651 1.651 17.5 700-900 [18] data
2017 NM6 1959-07-12 1.89 1.846 1.934 18.8 580–1300 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 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. [19]

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

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. [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

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] [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

  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. ^ a b "MPEC 2015-T86: 2015 TB145". IAU Minor Planet Center. 13 October 2015. Retrieved 14 October 2015. (K15TE5B)
  2. ^ a b c d "JPL Small-Body Database Browser: (2015 TB145)" (2018-11-20 last obs.). Jet Propulsion Laboratory. Retrieved 1 March 2020.
  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. 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. ^ 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 24 January 2016.
  7. ^ a b c d "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. ^ 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. 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. ^ a b c d 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. Retrieved 29 October 2015. (NASA Space Telescope Finds Fewer Asteroids Near Earth)
  17. ^ a b c "2015TB145 Ephemerides for 15 October 2015 through 31 October 2015". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 14 October 2015.
  18. ^ 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. 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. ^ 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 links

Wikimedia Commons has media related to 2015 TB145.
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