The First in a Series
|This artist's concept shows a broken-up asteroid.|
Image: Courtesy NASA/JPL-Caltech
On October 12, 2017, the asteroid 2012 TC4 is projected to make an exceptionally close approach to Earth, and it is possible that the media (alternative, mainstream, print, broadcast, and social) will go wild. Writeups will range from well written to poorly written, originally written to carbon copies, well research to poorly research, well intentioned to bad intentioned, and so forth. How is the consumer of media to make heads or tails of the hodgepodge of choices out there? The author plans a series of posts to give some background on 2012 TC4 in particular, some general knowledge about asteroids, their orbit, asteroid observing, asteroid risk list, and source information, to help the read navigate the mishmash of media out there.
What makes the Close-Approach on October 12, 2017, exceptional?
If we count 2008 TC3 and 2014 AA(both were small and impacted the Earth and would tie for first) 2012 TC4 could come in as the sixth closest known approach to date. While there is some uncertainty about how close the close-approach will be, there is sufficient observational data to rule out an impact on October 12, 2017, When talking about astronomical distances it can be tough to wrap one's head around this can lead one to use of analogies such as close shave which is not aways helpful. If one uses a basketball to serve as a model for the Earth it may be easier to grasp.
The Model (the Basketball Size Earth)
- Earth (Equatorial) radius: 4.2634965e-5 AU 3963.17 miles (6378.1 KM) - for the model 4.69507082121091 inches (11.93 CM)
- Earth (Equatorial) Circumference(assuming around Earth): 0.000267883358316 AU 24,901.32 miles (40,074.78 KM) -for the model 29.5 inches (74.93 CM)
- ISS(Perigee): 2.67383e-6 AU 248.55 miles (400.00 KM) -for the model 0.29 inches ( 0.75CM)
- ISS(apogee): 2.7407e-6 AU 254.76 miles (400.00 KM) -for the model 0.3 inches ( 0.77CM)
- The Close-Approach of 2012 TC4 on 2017-Oct-12 Minimum Possible Distance: 8.81780128572509e-05 AU (0.034 Lunar Distance (LD)) or 8196.66 miles (13191.24 KM) -for the model (after subtracting the radius)-5.02 inches (12.74 CM)
- The Close-Approach of 2012 TC4 on 2017-Oct-12 Nominal Distance: 9.6251580873557e-05 AU (0.037 Lunar Distance (LD)) or 8947.14 miles( 14399.03 KM) -for the model (after subtracting the radius)- 5.9 inches ( 15.0 CM)
- Geosynchronous orbit: 0.00023921463 AU (0.093 Lunar Distance (LD)) or 22236.39 miles (35786.00 KM) -for the model (after subtracting the radius)- 2.2 feet ( 0.67 M)
- Lunar Distance (LD): 0.003 AU or 238606.54 22236.39 miles (35786.00 KM) -for the model (after subtracting the radius)- 23.16 feet (7.06 M)
- The Close-Approach of 2012 TC4 on 2017-Oct-12 Maximum Possible Distance: 0.00289623510069374 AU (1.127 Lunar Distance (LD)) or 269221.87miles ( 433270.60 KM) -for the model (after subtracting the radius)- 26.19 feet ( 7.98M)
- Astronomical Unit: 389.171 Lunar Distance (LD) or 9.296e+7 miles (1.496e+8 KM) -for the model 1.7 miles (2.7 KM)
more to follow (Read The Second Part in a Series: Virtual Asteroids, The Observatory's Cat, a Lost Car Key, and 2012 TC4 Beyond the 2017-Oct-12 Close-Approach )
(as of 2017-01-16 )
- NOTE this is NOT a prediction of an impact but rather a statement there is insufficient observational data rule out an impact -- for information read Understanding Risk Pages by Jon Giorgini
- "The likelihood of a collision is zero, or is so low as to be effectively zero. Also applies to small objects such as meteors and bodies that burn up in the atmosphere as well as infrequent meteorite falls that rarely cause damage.."
- NEODyS Recovery Campaign: 2017-08-31t o 2017-10-24
- Last Observation (publish): 2012 10 11.74842 (by Volkssternwarte Drebach, Schoenbrunn(MPC code 113))