2015 TB145

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2015 TB145
250px
Discovery image of 2015 TB145 from the Pan-STARRS1 telescope, operated by the Institute for Astronomy at the University of Hawaii
Discovery[1]
Discovered by Pan-STARRS (F51)
Discovery date 10 October 2015
Designations
MPC designation 2015 TB145
Apollo 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)
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)
Physical characteristics
Dimensions 600 m (2,000 ft)[3][4]
5 hours,[4] 2.938 h (0.1224 d)[2]
0.06[4]
20.0[5][2]

2015 TB145 (also written 2015 TB145) is an Apollo near-Earth asteroid roughly Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value). in diameter. It safely passed 1.27 lunar distances from Earth on 31 October 2015 at 17:01 UTC.[6]

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][5][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.[8] 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.[6] The 2015 flyby was its closest approach to Earth in at least the next 500 years.

The media has nicknamed the asteroid the "Great Pumpkin"[9] after the animated Halloween television special It's the Great Pumpkin, Charlie Brown,[10] "Spooky",[11][12] the “Halloween Asteroid”,[13][14][15] and the “Skull Asteroid”[10] due to its human skull-like appearance following radio frequency images taken at Arecibo Observatory.[10]

File:PIA20043.png
Goldstone radar image of 2015 TB145

2015 flyby

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.[6]

The last approach this close by an object (with absolute magnitude < 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.[16] It is estimated that there are about 2400 near-Earth asteroids 300–500 meters in diameter, of which about 1100 have been discovered.[17]

During closest approach to Earth the asteroid reached about apparent magnitude 10,[18] 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.[18] 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.[18] After closest approach it quickly became too faint and too close to the Sun in the sky to be seen.[16]

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Animation of flyby

Asteroid flyby 2015 TB145.gif
An animation of the flyby, as seen from the center of the Earth, with hourly trace circles along the path of motion

Radar imagery

The close approach was studied with radar using Goldstone, the Green Bank Telescope,[16] and the Arecibo Observatory. It was one of the best radar targets of the year with a resolution as high as Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value). per pixel.[16] Bistatic radar images created with the Green Bank Telescope had a resolution of Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value). per pixel.[19] Arecibo images had a resolution of Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value). per pixel.[4]

October 30 October 31
12:55 - 13:08 UTC
File:PIA20041-Asteroid-2015TB145-Animation-20151030.gif 150px

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.[4][20] Orbital calculations by Petrus Jenniskens and Jérémie Vaubaillon show that it is not expected to produce associated meteors in 2015.[21] Meteoroids should pass more than 0.0007 AU (100,000 km; 65,000 mi) from Earth's orbit.[21] If meteoroids do cross Earth's path, the radiant should be Northern Eridanus.[21] Cameras for Allsky Meteor Surveillance (CAMS) did not detect any activity in the presumed area of the sky during 2013 and 2014.[21] 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.[4]

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.[7]

References

  1. ↑ 1.0 1.1 Lua error in package.lua at line 80: module 'strict' not found. (K15TE5B)
  2. ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Halloween Skies to Include Dead Comet Flyby. NASA-JPL press release. October 30, 2015
  5. ↑ 5.0 5.1 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 6.2 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ 10.0 10.1 10.2 Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ 16.0 16.1 16.2 16.3 Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ Lua error in package.lua at line 80: module 'strict' not found. (NASA Space Telescope Finds Fewer Asteroids Near Earth)
  18. ↑ 18.0 18.1 18.2 Lua error in package.lua at line 80: module 'strict' not found.
  19. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  20. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  21. ↑ 21.0 21.1 21.2 21.3 Lua error in package.lua at line 80: module 'strict' not found. (CBET 4154)

External links

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