4179 Toutatis

4179 Toutatis

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4179 Toutatis/1989 AC is an Apollo
Apollo asteroid
The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, the first asteroid of this group to be discovered by Karl Wilhelm Reinmuth...

, Alinda, and Mars-crosser asteroid
Mars-crosser asteroid
A Mars-crosser is an asteroid whose orbit crosses that of Mars. The known numbered Mars-crossers are listed here. They include the two numbered Mars trojans 5261 Eureka and ....

 with a chaotic
Chaos theory
Chaos theory is a field of study in mathematics, with applications in several disciplines including physics, economics, biology, and philosophy. Chaos theory studies the behavior of dynamical systems that are highly sensitive to initial conditions, an effect which is popularly referred to as the...

 orbit produced by a 3:1 resonance
Orbital resonance
In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers. Orbital resonances greatly enhance the mutual gravitational influence of...

 with the planet Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

, a 1:4 resonance with the planet Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

, and frequent close approaches to the terrestrial planet
Terrestrial planet
A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun...

s. Due to its very low orbital inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...

 (0.47°) and its orbital period of very nearly 4 years, Toutatis makes frequent close approaches to Earth, with a currently minimum possible distance (Earth MOID) of just 0.006 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

 (2.3 times as far as the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

). The approach on September 29, 2004, was particularly close, at 0.0104 AU (within 4 lunar distances
Lunar distance (astronomy)
In astronomy, a lunar distance is a measurement of the distance from the Earth to the Moon. The average distance from Earth to the Moon is 384,400 kilometers...

) from Earth, presenting a good opportunity for observation, with Toutatis shining at magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

 8.8 when brightest. The most recent close approach of 0.0502 AU happened on November 9, 2008. The next close approach will be December 12, 2012, at a distance of 0.046 AU, and at magnitude 10.7. By the middle of May 2012 the asteroid will become brighter than magnitude 19.5.

Its rotation combines two separate periodic motions into a non-periodic result; to someone on the surface of Toutatis, the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 would seem to rise and set in apparently random locations and at random times at the asteroid's horizon.

It 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
Christian Pollas
Christian Pollas is a French astronomer.He has discovered tens of asteroids, some co-discovered with Eric W. Elst, including notably the Aten asteroid 1989 UQ, the Apollo asteroid 4179 Toutatis, and the Amor asteroid 1990 VB....

, and was named after the Celtic god
Celtic polytheism
Celtic polytheism, commonly known as Celtic paganism, refers to the religious beliefs and practices adhered to by the Iron Age peoples of Western Europe now known as the Celts, roughly between 500 BCE and 500 CE, spanning the La Tène period and the Roman era, and in the case of the Insular Celts...

 Toutatis
Toutatis
Toutatis or Teutates was a Celtic god worshipped in ancient Gaul and Britain. On the basis of his name's etymology, he has been widely interpreted to be a tribal protector. Today, he is best known under the name Toutatis through the Gaulish catchphrase "By Toutatis!", invented for the Asterix...

/Teutates, known to popular culture as the God the cartoon character Astérix
Asterix
Asterix or The Adventures of Asterix is a series of French comic books written by René Goscinny and illustrated by Albert Uderzo . The series first appeared in French in the magazine Pilote on October 29, 1959...

's chief Vitalstatistix evokes so that the sky may never fall on his head.

Radar
Radar astronomy
Radar astronomy is a technique of observing nearby astronomical objects by reflecting microwaves off target objects and analyzing the echoes. This research has been conducted for six decades. Radar astronomy differs from radio astronomy in that the latter is a passive observation and the former an...

 imagery has shown 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
Rubble pile
In astronomy, rubble pile is the informal name for an object that is not a monolith, consisting instead of numerous pieces of rock that have coalesced under the influence of gravity...

".
The low inclination of the orbit allows frequent transits
Astronomical transit
The term transit or astronomical transit has three meanings in astronomy:* A transit is the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point...

, where the inner planets Mercury, Venus, Earth, and Mars can appear to cross the Sun. Earth did this in January 2009, and will also do it in 2012, 2016, and 2020.

Dual resonances and chaotic behaviour


Toutatis has a 3:1 orbital resonance
Orbital resonance
In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers. Orbital resonances greatly enhance the mutual gravitational influence of...

 with Jupiter and a near-1:4 resonance with Earth. The frequent close approaches to the terrestrial planets lead to chaotic
Chaos theory
Chaos theory is a field of study in mathematics, with applications in several disciplines including physics, economics, biology, and philosophy. Chaos theory studies the behavior of dynamical systems that are highly sensitive to initial conditions, an effect which is popularly referred to as the...

 behaviour in the orbit of Toutatis, making precise long-term predictions of its location progressively inaccurate over time. Estimates in 1993 put the Lyapunov time horizon
Lyapunov exponent
In mathematics the Lyapunov exponent or Lyapunov characteristic exponent of a dynamical system is a quantity that characterizes the rate of separation of infinitesimally close trajectories...

 for predictability at around 50 years, after which the uncertainty region becomes larger with each close approach to a planet. Without the perturbations
Perturbation (astronomy)
Perturbation is a term used in astronomy in connection with descriptions of the complex motion of a massive body which is subject to appreciable gravitational effects from more than one other massive body....

 from the terrestrial planets the Lyapunov time would be close to 10,000 years.

Collision risk


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
Potentially Hazardous Object
A potentially hazardous object is an asteroid or comet with an orbit such that it has the potential to make close approaches to the Earth and a size large enough to cause significant regional damage in the event of impact....

. The likelihood of collision in the distant future is considered to be very small. 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 fear mongering
Fear mongering
Fear mongering is the use of fear to influence the opinions and actions of others towards some specific end...

 doomsday crowd
Doomsday cult
Doomsday cult is an expression used to describe groups who believe in Apocalypticism and Millenarianism, and can refer both to groups that prophesy catastrophe and destruction, and to those that attempt to bring it about...

spread misinformation about Toutatis back in 2004.

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