Asteroid 4179 Toutatis
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Asteroid 4179 Toutatis
Asteroid 4179 Toutatis was discovered on January 4, 1989 by French astronomers observing Jupiter's satellites. The huge asteroid, which is some 2.9 miles (4.6 kilometers) long and 1.5 miles (2.4 kilometers) wide, was named after a Celtic god who features prominently in the Asterix comic book series popular in France. (Toutatis protects Asterix and his friends, who fear nothing except the possibility that the sky may fall on their heads someday.)
Toutatis has a four-year orbit that extends from just inside the Earth's orbit to the main asteroid belt between Mars and Jupiter. It frequently approaches very close to earth. Its closest approach to earth was on September 29, 2004, when it was 962,951 miles (1,549,719 kilometers) away. Since you are reading this entry after this date, you know that the panicky doomsday rumors about an impending collision between Toutatis and the Earth that spread on the Internet during the months leading up to September 2004 were not true. It was said that if Toutatis were to collide with the Earth, it would release energy equivalent to tens of thousands of hydrogen bombs and completely obliterate the light of the sun.
Last updated: March 06, 2005.
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4179 Toutatis
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Discovery
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| Discovered by | Christian Pollas |
| Discovery date | January 4, 1989 |
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Designations
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| Named after | Toutatis |
| Alternate name(s) | 1934 CT; 1989 AC |
| Minor planet category |
Apollo, Alinda, Mars-crosser |
| Epoch 2012-Mar-14 (JD 2456000.5) | |
| Aphelion | 4.1215 AU (616.5 Gm) |
| Perihelion | 0.93732 AU (140.2 Gm) |
| Semi-major axis | 2.5294 AU (378.3 Gm) |
| Eccentricity | 0.62943 |
| Orbital period | 4.02 a (1469.3 d) |
| Average orbital speed | 16.69 km/s |
| Mean anomaly | 299.56° |
| Inclination | 0.44602° |
| Longitude of ascending node | 124.50° |
| Argument of perihelion | 278.55° |
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Physical characteristics
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| Dimensions | 4.5×2.4×1.9 km |
| Mass | 5.0×1013 kg |
| Mean density | 2.1 g/cm³ |
| Equatorial surface gravity | 0.0010 m/s² |
| Escape velocity | 0.0019 km/s |
| Rotation period | 5.41 to 7.33 d[1] |
| Albedo | 0.13[1] |
| Temperature | ~174 K |
| Spectral type | S |
| Apparent magnitude | 8.8 (when near Earth)[2] to 22.4[3] |
| Absolute magnitude (H) | 15.30[1] |
4179 Toutatis/1989 AC (
/tuːˈtɑːtɨs/ too-TAH-tis) is an Apollo, Alinda, and Mars-crosser asteroid with a chaotic orbit produced by a 3:1 resonance with the planet Jupiter, a 1:4 resonance with the planet Earth, and frequent close approaches to the terrestrial planets, including Earth.[4] It is listed as a potentially hazardous object,[5] although the odds of a collision with the Earth are very small.[6]
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Contents
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Properties
4179 Toutatis was first sighted on February 10, 1934, as object 1934 CT, and then promptly lost. It remained a lost asteroid for several decades until it was recovered on January 4, 1989, by Christian Pollas, and was named after the Celtic god Toutatis/Teutates—known to popular culture as the God that the cartoon character Astérix's chief Vitalstatistix evokes so that the sky may never fall on his head.
The spectral properties suggest that this is an S-type, or stony asteroid, consisting primarily of silicates. It has a moderately bright Bond albedo of 0.13.[1] Radar imagery shows that Toutatis is a highly irregular body consisting of two distinct "lobes", with maximum widths of about 4.6 km and 2.4 km respectively. It is hypothesized that Toutatis formed from two originally separate bodies which coalesced at some point, with the resultant asteroid being compared to a "rubble pile".
Its rotation combines two separate periodic motions into a non-periodic result; to someone on the surface of Toutatis, the Sun would seem to rise and set in apparently random locations and at random times at the asteroid's horizon. It has a rotation period around its long axis (Pψ) of 5.38 days. This long axis is precessing with a period (Pφ) of 7.38 days.[7] The asteroid may have lost most of its original angular momentum and entered into this tumbling motion as a result of the YORP effect.[8]
Orbit
With a semimajor axis of 2.5294 AU, or roughly 2.5 times the separation of the Earth from the Sun, Toutatis has a 3:1 orbital resonance with Jupiter and a near-1:4 resonance with Earth.[4][9] Thus it completes one orbit around the Sun for every 4.02 annual orbits of the Earth. The gravitational perturbations caused by frequent close approaches to the terrestrial planets lead to chaotic behaviour in the orbit of Toutatis,[10] making precise long-term predictions of its location progressively inaccurate over time.[10] Estimates in 1993 put the Lyapunov time horizon for predictability at around 50 years,[10] after which the uncertainty region becomes larger with each close approach to a planet. Without the perturbations from the terrestrial planets the Lyapunov time would be close to 10,000 years.[10] The initial observations which showed its chaotic behaviour were made by Wiśniewski.[11]
The low inclination (0.47°) of the orbit allows frequent transits, where the inner planets Mercury, Venus, Earth, and Mars can appear to cross the Sun as seen from the perspective of the asteroid. Earth did this in January 2009, and will also do it in July 2012, 2016, and 2020.[12]
Close approaches and collision risk
Toutatis makes frequent close approaches to Earth, with a currently minimum possible distance (Earth MOID) of just 0.006 AU (2.3 times as far as the Moon).[1] The approach on September 29, 2004, was particularly close, at 0.0104 AU[13] (within 4 lunar distances) from Earth, presenting a good opportunity for observation, with Toutatis shining at magnitude 8.8 when brightest.[2] A more recent close approach of 0.0502 AU (7,510,000 km; 4,670,000 mi) happened on November 9, 2008.[13][5] The next close approach will be December 12, 2012, at a distance of 0.046 AU (6,900,000 km; 4,300,000 mi),[13][5] and at magnitude 10.7.[14] At magnitude 10.7, the asteroid will not be visible to the naked eye, but may be visible to experienced observers using high-end binoculars. By the middle of May 2012 the asteroid will become brighter than magnitude 19.5.[15] The probability of the orbit intersecting Earth is essentially zero for at least the next six centuries.[16]
Given that Toutatis makes many close approaches the Earth, such as in 1992, 1996, 2000, 2004, 2008, and 2012, it is listed as a potentially hazardous object.[5] With an uncertainty parameter of 0,[1] the orbit of Toutatis is very well determined for the next few hundred years.[5] The probability of the orbit intersecting Earth is zero for at least the next six centuries.[16] The likelihood of collision in the distant future is considered to be very small.[6] As a planet-crossing asteroid, Toutatis is likely to be ejected from the Solar System on a time scale of a few tens of thousands of years, giving it a limited number of opportunities to strike Earth before disappearing forever. As with many near-Earth objects, the doomsayers spread rumors about Toutatis back in 2004.[17]
See also
References
- ^ a b c d e f g "JPL Small-Body Database Browser: 4179 Toutatis (1989 AC)". http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1989AC. Retrieved 2012-03-23.
- ^ a b "AstDys (4179) Toutatis Ephemerides for 2004". Department of Mathematics, University of Pisa, Italy. http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.1&n=4179&oc=500&y0=2004&m0=9&d0=28&h0=0&mi0=0&y1=2004&m1=9&d1=30&h1=0&mi1=0&ti=1&tiu=hours. Retrieved 2010-06-27.
- ^ "AstDys (4179) Toutatis Ephemerides 2059". Department of Mathematics, University of Pisa, Italy. http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.1&n=4179&oc=500&y0=2059&m0=8&d0=31&h0=0&mi0=0&y1=2059&m1=9&d1=14&h1=0&mi1=0&ti=1.0&tiu=days. Retrieved 2010-06-27.
- ^ a b "Trick or Treat: It's Toutatis!". Science@Nasa. 2000-10-31. Archived from the original on 29 January 2009. http://science.nasa.gov/headlines/y2000/ast31oct_1.htm. Retrieved 2009-01-27.
- ^ a b c d e "JPL Close-Approach Data: 4179 Toutatis (1989 AC)". 2011-05-22 last obs (arc=77.28 years). http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Toutatis;cad=1#cad. Retrieved 2011-11-13.
- ^ a b "Close call for earth ahead? – possible collision with asteroid Toutatis". USA Today (Society for the Advancement of Education). 1993. http://findarticles.com/p/articles/mi_m1272/is_n2577_v121/ai_13953460/.
- ^ Belton, Michael J. S. (August 2002), "The Diagnosis of Complex Rotation in the Lightcurve of 4179 Toutatis and Potential Applications to Other Asteroids and Bare Cometary Nuclei", Icarus 158 (2): 305–311, Bibcode 2002Icar..158..305M, doi:10.1006/icar.2002.6892.
- ^ Bottke, William, Jr. (October 2007), "Implications of the YORP Effect for Our Understanding of Asteroid Evolution", Bulletin of the American Astronomical Society 39: 416, Bibcode 2007DPS....39.0507B.
- ^ "Toutatis is in a 3:1 mean-motion resonance with Jupiter (rotating frame)". Gravity Simulator. http://www.orbitsimulator.com/gravity/articles/toutatis.html. Retrieved 2009-01-27.
- ^ a b c d Whipple, L.; Shelus, Peter J. (1993). "Long-Term Dynamical Evolution of the Minor Planet (4179) Toutatis". Icarus 105 (2): 408–419. Bibcode 1993Icar..105..408W. doi:10.1006/icar.1993.1137.
- ^ http://www.minorplanet.info/MPB/MPB_21-2.pdf
- ^ "Solex by Aldo Vitagliano". http://chemistry.unina.it/~alvitagl/solex/. Retrieved 2009-03-03.
- ^ a b c "NEODys (4179) Toutatis Close Approaches". Department of Mathematics, University of Pisa, Italy. http://newton.dm.unipi.it/neodys/index.php?pc=1.1.8&n=Toutatis. Retrieved 2009-03-20.
- ^ "NEODys (4179) Toutatis Ephemerides for December 2012". Department of Mathematics, University of Pisa, Italy. http://hamilton.dm.unipi.it/astdys/index.php?pc=1.1.3.1&n=4179&oc=500&y0=2012&m0=12&d0=12&h0=0&mi0=0&y1=2012&m1=12&d1=19&h1=0&mi1=0&ti=3&tiu=hours. Retrieved 2010-06-27.
- ^ "(4179) Toutatis Ephemerides for May 2012". NEODyS (Near Earth Objects - Dynamic Site). http://newton.dm.unipi.it/neodys/index.php?pc=1.1.3.1&n=4179&oc=500&y0=2012&m0=05&d0=01&h0=0&mi0=0&y1=2012&m1=06&d1=01&h1=0&mi1=0&ti=1.0&tiu=days. Retrieved 2011-11-13.
- ^ a b Ostro, S. J.; Hudson, R. S.; Rosema, K. D.; Giorgini, J. D.; Winkler, R.; Yeomans, D. K.; Chodas, P. W.; Slade, M. A (1998). "Asteroid 4179 Toutatis: 1996 Radar Observations". Icarus 137: 122–139. hdl:2014/19433.
- ^ David Morrison (September 27, 2004). "Close Flyby This Week from Asteroid Toutatis". Asteroid and Comet Impact Hazards (NASA). http://impact.arc.nasa.gov/news_detail.cfm?ID=151. Retrieved 2011-11-13.
External links
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Wikimedia Commons has media related to: 4179 Toutatis |
- Toutatis radar information
- Toutatis Home Page, by one of the asteroid's discoverers (private access only)
- Space.com: Video of Toutatis's close approach to Earth, 29 Sept, 2004
- Interesting views of asteroid
- Astrobiology Magazine article
- Simulating the orbit of Toutatis exposes its resonance with Jupiter
- Orbital simulation from JPL (Java) / Ephemeris
- Toutatis Hi-res Video
- Six-Centimeter Radar Observations of 4179 Toutatis
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