2012 TC4

2012 TC4

2012 TC4 appears as a dot of this composite of 37 individual 50-second exposures.[1]
Discovery[2]
Discovered by Pan-STARRS F51
Discovery date October 4, 2012
Designations
Apollo
NEO
Orbital characteristics[3]
Epoch 17 February 2017 (JD 2457800.5)
Uncertainty parameter 1
Observation arc 1766 days (4.84 years)
Aphelion 1.87754518 AU (280.876761 Gm)
Perihelion 0.9337118 AU (139.68130 Gm)
1.40562850 AU (210.279031 Gm)
Eccentricity 0.3357336
1.67 yr (608.70134 d)
198.5086°
0° 35m 29.123s /day
Inclination 0.85638°
198.253783°
222.5613°
Known satellites none
Earth MOID 0.000249707 AU (37,355.6 km; 23,211.7 mi)
Jupiter MOID 3.461 AU
Physical characteristics
Dimensions 11-28 meters[note 1]
12 minutes, 13.7 seconds[4]
26.2 (as of August 6, 2017)[5]
26.8[6][3]
  1. ↑ assuming an Albedo of between 0.05 and 0.3 (reflecting between 5% and 30% of the light that shines on it)

2012 TC4 is an Apollo near-Earth asteroid roughly 20 meters in diameter. On October 12, 2017 at 5:42 UT, the asteroid will pass 0.00033 AU (49,000 km; 31,000 mi) from Earth.[7] NEODyS shows there is no chance of an Earth impact before October 12, 2050.[8] Based on observations from 2012, the asteroid rates -4.78 on the Palermo scale, with a 1 in 14,000 chance of impact over the next hundred years.[9]

The asteroid was not expected to become bright enough to recover with automated astronomical surveys until early September,[10] but it was successfully recovered with the Very Large Telescope (VLT) on July 27, 2017 at an apparent magnitude of 26.8,[11] making it one of the dimmest asteroid recoveries ever. As such, 2012 TC4 has become the first known asteroid ever to be observed passing less than 1 Lunar distance from Earth twice in a row.

2012 TC4 will reach a maximum apparent magnitude of 12.8 just prior to its closest approach, soon after which it will appear to be too close to the Sun to be seen with telescopes.[12]

2012

2012 TC4 was discovered on October 4, 2012 at apparent magnitude 20.1 while the asteroid was 0.03 AU (4,500,000 km; 2,800,000 mi) from Earth.[2] During the 2012 close approach, the asteroid only had an observation arc of 7 days, between October 4, 2012, and October 11, 2012, so the exact distance of the 2017 closest approach was poorly constrained. With the 7 day observation arc, the asteroid had a 3-sigma chance of passing between 0.00008818 and 0.002896 AU (0.034 to 1.127 LD, 13,200–433,200 km, 8,200-269,200 mi) from Earth on October 12, 2017.[13] Astronomers were certain that it would not pass closer than 6,800 km from the surface of Earth.[14] The asteroid had been known to make close approaches to Earth in the past, including the approach of 0.000634 AU (0.247 LD, 94,800 km, 58,900 mi) on October 12, 2012,[7] during the apparition for which the asteroid was discovered.

Paul Chodas of NASA's Center for Near-Earth Object Studies, and Vishnu Reddy of the University of Arizona's Lunar and Planetary Laboratory, viewed the 2017 flyby (inside of the orbit of the Moon) as a way to test and refine the global asteroid detection and tracking network designed to give warning of objects heading toward Earth.[14] Reddy coordinated the effort, involving over a dozen institutions worldwide.[14][15]

2017

The asteroid was recovered with the Very Large Telescope on July 27, 2017 at apparent magnitude 26.8 while the asteroid was 0.4 AU (60,000,000 km; 37,000,000 mi) from Earth.[11] At the time of recovery the asteroid was about 100 million times fainter than what can be seen with the naked eye[16] and 500 times fainter than when it was discovered in 2012. As of result of the 2017 recovery observations, it is known that on October 12, 2017 at 5:42 UT, the asteroid will pass 0.00033 AU (49,000 km; 31,000 mi) from Earth.[7] Then at 19:19 UT, the asteroid will pass 0.00185 AU (277,000 km; 172,000 mi) from the Moon.[7] The asteroid will peak at about apparent magnitude 12.8,[12] and will be too faint to be seen without a telescope.

Rotation

Studies of the asteroid's light curve found it to have a rotation period of approximately 12 minutes and 14 seconds,[4] relatively slow for asteroids of its size (10–20 meter). As a comparison, asteroid 2014 RC, a similarly-sized NEO, has a rotation period of only 16 seconds.

See also

References

  1. ↑ "A Very Close Encounter". www.eso.org. Retrieved 11 August 2017.
  2. 1 2 "MPEC 2012-T18 : 2012 TC4". IAU Minor Planet Center. 2012-10-07. Retrieved 2017-03-14. (K12T04C)
  3. 1 2 "JPL Small-Body Database Browser: 2012 TC4". JPL. NASA. Archived from the original on 22 October 2014. Retrieved 1 April 2016.
  4. 1 2 "Polishook 2013, MPB 40, 42". ADS. Minor Planet Bulletin. Bibcode:2013MPBu...40...42P. Retrieved 22 October 2014.
  5. ↑ "NEODyS-2 2012TC4". Department of Mathematics, University of Pisa, Italy. Retrieved 2017-03-13.
  6. ↑ "IAU Minor Planet Center - 2012 TC4". Minor Planet Center. IAU. Archived from the original on 22 October 2014. Retrieved 22 October 2014.
  7. 1 2 3 4 "Close Approach table for 2012 TC4". JPL. NASA. Retrieved 22 October 2014.
  8. ↑ "NEODyS-2 2012TC4 Impactor Table". Department of Mathematics, University of Pisa, Italy. Archived from the original on 7 August 2017. Retrieved 2017-08-07.
  9. ↑ "Earth Impact Risk Summary: 2012 TC4". NASA/JPL Near-Earth Object Program Office. Archived from the original on 2012-11-24. Retrieved 2017-03-13.
  10. ↑ "NEODyS-2 Possible recovery list". Department of Mathematics, University of Pisa, Italy. Retrieved 2017-03-14.
  11. 1 2 "MPEC 2017-P26 : 2012 TC4". IAU Minor Planet Center. 2017-08-06. Retrieved 2017-08-06. (K12T04C)
  12. 1 2 "2012TC4 Ephemerides for 12 October 2017". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 2017-08-07.
  13. ↑ "Close Approach table for 2012 TC4 (using 7 day obs arc)". JPL. NASA. Retrieved 22 October 2014.
  14. 1 2 3 "Asteroid Flyby Will Benefit NASA Detection and Tracking Network". JPL. NASA. 2017-07-28.
  15. ↑ CNN, Nancy Coleman (1 August 2017). "NASA's planetary defense system will be put to the test in October". CNN. Retrieved 2 August 2017.
  16. ↑ Math:


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