4179 Toutatis (

provisional designation Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calcu ...

) is an elongated, stony

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

and slow rotator, classified as a

near-Earth object A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun ( perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orbit a ...

and

potentially hazardous asteroid A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and which is large enough to cause significant regional damage in the event of impact. Th ...

of the

Apollo asteroid The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, discovered by German astronomer Karl Reinmuth in the 1930s. They are Earth-crossing asteroids that have an orbital semi-major axis greater than that of the Ear ...

group, approximately 2.5 kilometers in diameter. Discovered by French astronomer

Christian Pollas Christian Pollas (b. 1947) is a French astronomer, known for the discovery and observation of minor planets and supernovae. Pollas is credited by the Minor Planet Center with the discovery of 26 asteroids, some co-discovered with Eric W. Elst, ...

Caussols Caussols (; ; ) is a commune in the Alpes-Maritimes department in southeastern France. It is known for the CERGA Observatory on the Calern plateau. Demographics See also *Communes of the Alpes-Maritimes department The following is a l ...

in 1989, the asteroid was named after

Toutatis Teutates (spelled variously Toutatis, Totatis, Totates) is a Celtic god attested in literary and epigraphic sources. His name, which is derived from a proto-Celtic word meaning "tribe", suggests he was a national god, tribal deity. The Roman po ...

from Celtic mythology. Toutatis is also a

Mars-crosser asteroid A Mars-crossing asteroid (MCA, also Mars-crosser, MC) is an asteroid whose orbit crosses that of Mars. Some Mars-crossers numbered below 100000 are listed here. They include the two numbered Mars trojans 5261 Eureka and . Many databases, for i ...

with a

chaotic Chaotic was originally a Danish trading card game. It expanded to an online game in America which then became a television program based on the game. The program aired on 4Kids TV (Fox affiliates, nationwide), Jetix, The CW4Kids, Cartoon Netwo ...

orbit produced by a 3:1

resonance Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximu ...

with the planet

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

, a 1:4 resonance with the planet

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

, and frequent close approaches to the

terrestrial planet A terrestrial planet, tellurian 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 accepted by the IAU are the inner planets closest to ...

s, including Earth. In December 2012, Toutatis passed within about 18 lunar distances of Earth. The Chinese lunar probe

Chang'e 2 Chang'e 2 (; ) is a Chinese uncrewed lunar probe that was launched on 1 October 2010. It was a follow-up to the Chang'e 1 lunar probe, which was launched in 2007. Chang'e 2 was part of the first phase of the Chinese Lunar Exploration Program, ...

flew by the asteroid at a distance of 3.2 kilometers and a relative velocity of 10.73 km/s. Toutatis approached Earth again in 2016, but will not make another notably close approach until 2069.

Properties

Toutatis was first sighted on 10 February 1934, as object 1934 CT, but lost soon afterwards. It remained a

lost asteroid Lost or LOST may refer to getting lost, or to: Arts, entertainment, and media Television * ''Lost'' (TV series), a 2004 American drama series about people who become stranded on a mysterious island * ''Lost'' (2001 TV series), a short-lived Ameri ...

for several decades until it was rediscovered on 4 January 1989 by

French French may refer to: * Something of, from, or related to France ** French language, which originated in France ** French people, a nation and ethnic group ** French cuisine, cooking traditions and practices Arts and media * The French (band), ...

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

, and was named after the

Celtic god The gods and goddesses of the pre-Christian Celtic peoples are known from a variety of sources, including ancient places of worship, statues, engravings, cult objects, and place or personal names. The ancient Celts appear to have had a pantheon ...

of tribal protection

(Teutates). The name of this god is very familiar in

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

due to the

catchphrase A catchphrase (alternatively spelled catch phrase) is a phrase or expression recognized by its repeated utterance. Such phrases often originate in popular culture and in the arts, and typically spread through word of mouth and a variety of mass ...

''Par Toutatis!'' by the Gauls in the

comics a Media (communication), medium used to express ideas with images, often combined with text or other visual information. It typically the form of a sequence of Panel (comics), panels of images. Textual devices such as speech balloons, Glo ...

Asterix ''Asterix'' ( or , "Asterix the Gauls, Gaul"; also known as ''Asterix and Obelix'' in some adaptations or ''The Adventures of Asterix'') is a Franco-Belgian comics, French comic album book series, series about a Gaulish village which, thanks ...

. The spectral properties suggest that this is an S-type, or stony asteroid, consisting primarily of

silicate A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...

s. It has a moderate

Bond albedo The Bond albedo (also called spheric albedo, planetary albedo, and bolometric albedo), named after the American astronomer George Phillips Bond (1825–1865), who originally proposed it, is the fraction of power in the total electromagnetic radi ...

of 0.13.

Radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

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 (a

contact binary In astronomy, a contact binary is a binary star system whose component stars are so close that they touch each other or have merged to share their gaseous envelopes. A binary system whose stars share an envelope may also be called an overcontac ...

), with the resultant asteroid being compared to a

rubble pile In astronomy, a rubble pile is a celestial body that consists of numerous pieces of debris that have coalesced under the influence of gravity. Rubble piles have low density because there are large cavities between the various chunks that make the ...

. Its rotation combines two separate periodic motions into a non-periodic result; to someone on the surface of Toutatis, the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

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

rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...

around its long axis (P_ψ) of 5.38 days. This long axis is precessing with a period (P_φ) of 7.38 days. The asteroid may have lost most of its original angular momentum and entered into this tumbling motion as a result of the

YORP effect The Yarkovsky–O'Keefe–Radzievskii–Paddack effect, or YORP effect for short, changes the rotation state of a small astronomical body – that is, the body's spin rate and the obliquity of its pole(s) – due to the scattering of solar radia ...

Orbit

With a

semimajor axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the long ...

of 2.5294 AU, or roughly 2.5 times the distance between Earth and the Sun, Toutatis has a 3:1

orbital resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relation ...

with Jupiter and a near-1:4 resonance with Earth making it a member of the

Alinda asteroid The Alinda asteroids are a dynamical group of asteroids with a semi-major axis of about 2.5 AU and an orbital eccentricity approximately between 0.4 and 0.65. It thus completes one orbit around the Sun for every 4.02 annual orbits of Earth. The

gravitational perturbation In astronomy, perturbation is the complex motion of a massive body subjected to forces other than the gravitational attraction of a single other massive body. The other forces can include a third (fourth, fifth, etc.) body, resistance, as fro ...

s caused by frequent close approaches to the terrestrial planets lead to

behavior 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 for predictability at around 50 years, 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. The initial observations that showed its chaotic behavior were made by

Wiśniewski Wiśniewski (; feminine: Wiśniewska, plural Wiśniewscy) is the third most common surname in Poland (111,174 people in 2009).Ministry of Interior (Poland). Statystyka najpopularniejszych nazwisk występujących w Polsce in 2009'' (The most popula ...

. The low

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

(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 Toutatis. Earth did this in January 2009, July 2012, July 2016 and 2020.

Close approaches and collision risk

Toutatis makes frequent close approaches to Earth, with a currently minimum possible distance (Earth

MOID Minimum orbit intersection distance (MOID) is a measure used in astronomy to assess potential close approaches and collision risks between astronomical objects. It is defined as the distance between the closest points of the osculating orbits of ...

) of just 0.006 AU (2.3 times as far as the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

). The approach on 29 September 2004 was particularly close, at 0.0104 AU (within 4 lunar distances) from Earth, presenting a good opportunity for observation, with Toutatis having an

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of 8.8 at its brightest. A close approach of happened on 9 November 2008. The most recent close approach was on 12 December 2012, at a distance of , with a magnitude of 10.7. At magnitude 10.7, Toutatis was not visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

, but just visible to experienced observers using high-end

binoculars Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...

. During the 2012 encounter Toutatis was recovered on 21 May 2012, by the

Siding Spring Survey The Siding Spring Survey (SSS) was a near-Earth object search program that used the 0.5-metre Uppsala Southern Schmidt Telescope at Siding Spring Observatory, New South Wales, Australia. It was the southern hemisphere counterpart of the Catalin ...

18.9. A close approach will be 5 November 2069, at . Given that Toutatis makes many close approaches to Earth, such as in 1992, 1996, 2000, 2004, 2008, 2012, and 2016, it is listed as a

potentially hazardous object A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and which is large enough to cause significant regional damage in the event of impact. Th ...

. With an

uncertainty parameter The uncertainty parameter ''U'' is introduced by the Minor Planet Center (MPC) to quantify the uncertainty of a perturbed orbital solution for a minor planet. The parameter is a logarithmic scale from 0 to 9 that measures the anticipated longitud ...

of 0, the orbit of Toutatis is very well determined for the next few hundred years. The probability of the orbit intersecting Earth is essentially zero for at least the next six centuries. 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 inner Solar System within a few million years. In 2004 a

chain e-mail A chain letter is a message that attempts to convince the recipient to make a number of copies and pass them on to a certain number of recipients. The "chain" is an exponentially growing pyramid (a tree graph) that cannot be sustained indefinit ...

falsely claimed that Toutatis had a 63% chance of impacting Earth then. In fact, Toutatis passed by at 1.5 million kilometres, or about four Earth–Moon distances, as predicted. In 2006 Toutatis came closer than 2 AU to Jupiter; its orbit lies inside of Jupiter's. In the 2100s, it will approach Jupiter many times at a similar distance.

Physical characteristics

Large amounts of data of Toutatis were obtained during

's flyby. Toutatis is not a monolith, but most likely a coalescence of shattered fragments. This bifurcated asteroid is shown to be mainly consisting of a head (small lobe) and a body (large lobe). The two major parts are not round in shape, and their surfaces have a number of large facets. In comparison with radar models, the proximate observations from Chang'e 2's flyby have revealed several remarkable discoveries concerning Toutatis, among which the presence of the giant basin at the big end appears to be one of the most compelling geological features, and the sharply perpendicular silhouette in the neck region that connects the head and body is also quite novel. A large number of boulders and several short linear structures are also apparent on the surface.

Giant basin

The giant basin at the big end of Toutatis has a diameter of ~805 m, suggesting that one or more impactors may have collided with it there. The most significant feature is the ridge around the largest basin. The wall of this basin has a relatively high density of lineaments, some of which seem to be concentric to the basin. These ridges are indicative of an internal structure of small bodies and most of the ridges near the largest basin at the big end are most likely related to the huge stress energy during impact.

Observation

Toutatis has been observed with radar imaging from the

Arecibo Observatory The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science F ...

and the

Goldstone Solar System Radar The Goldstone Solar System Radar (GSSR) is a large radar system used for investigating objects in the Solar System, a field called radar astronomy. Located in the desert near Barstow, California, it comprises a 500-kW X-band (8500 MHz) transmitte ...

during the asteroid's prior Earth flybys in 1992, 1996, 2000, 2004, and 2008. It was also observed with radar during the December 2012 flyby and observed more distant flyby with radar in December 2016. After 2016, Toutatis will not pass close to Earth again until 2069. Resolution of the radar images is as fine as 3.75 m per pixel, providing data to model Toutatis's shape and spin state.

Exploration

The Chinese lunar probe

departed from the Sun–Earth L2 point in April 2012 and made a flyby of Toutatis on 13 December 2012, with closest approach being 3.2 kilometers and a relative velocity of 10.73 km/s, when Toutatis was near its closest approach to Earth. It took several pictures of the asteroid, revealing it to be a dusty red/orange color.

References

External links

More Chang'E 2 Toutatis flyby images
(Emily Lakdawalla : 2013/01/20)

(Planetary Society)
CCTV13 Special
(all in Mandarin)
China joined the interplanetary club by successfully imaging the asteroid Toutatis
(

Franck Marchis Franck Marchis (born April 6, 1973 in Caen, France), astronomer and planetary scientist, is best known for his discovery and characterization of multiple asteroids, his study of Io volcanism and imaging of exoplanets, planets around other star ...

, 14 December 2012)
Chinese space probe flies by asteroid Toutatis
(Xinhua 2012-12-15)
Surface Features of Asteroid Toutatis Revealed by Radar
(YouTube: JPLnews)

* ttp://www.solarviews.com/eng/toutatis.htm Interesting views of asteroid
Astrobiology Magazine article
(09/27/04)

(Gravity Simulator)

(Emily Lakdawalla 2012-12-06)

Size comparison

Chang'e 2 fly-by of Toutatis
Presentation from Small Bodies Assessment Group (SBAG) 8 meeting
Boulders on asteroid Toutatis as observed by Chang'e-2
(

arXiv arXiv (pronounced as "archive"—the X represents the Chi (letter), Greek letter chi ⟨χ⟩) is an open-access repository of electronic preprints and postprints (known as e-prints) approved for posting after moderation, but not Scholarly pee ...

:1511.00766 : 3 Nov 2015) * * * {{DEFAULTSORT:Toutatis 004179 004179 Discoveries by Christian Pollas Named minor planets 004179 004179 20121213 004179 004179 20121212 19890104