![]() Toutatis imaged by Chang'e 2 during its flyby | |
Discovery [1] | |
---|---|
Discovered by | Christian Pollas |
Discovery site | Caussols |
Discovery date | 4 January 1989 |
Designations | |
(4179) Toutatis | |
Pronunciation | /taʊˈteɪtɪs/ |
Named after | Toutatis (Celtic mythology) [2] |
| |
Adjectives | Toutatian [4] |
Orbital characteristics [3] | |
Epoch 27 November 2008 (JD 2454797.5) | |
Uncertainty parameter 0 | |
Observation arc | 83.29 yr (30,422 days) |
Earliest precovery date | 10 February 1934 |
Aphelion | 4.1242 AU |
Perihelion | 0.9399 AU |
2.5321 AU | |
Eccentricity | 0.6288 |
4.03 yr (1,472 days) | |
5.1220° | |
0° 14m 40.56s / day | |
Inclination | 0.4460° |
124.30° | |
278.75° | |
Earth MOID | 0.0064 AU (2.5 LD) |
Physical characteristics | |
Dimensions | |
Mean diameter | 2.45 km [6] |
Mass | 1.9×1013 kg [7] |
Mean density | 2.5 g/cm3 [7] |
176 h (7.3 d) [8] | |
0.13 [3] | |
Sk (SMASSII) [3] | |
8.8–22.4 [9] [10] | |
15.30 [3] | |
4179 Toutatis (Provisional designation 1989 AC) is an elongated, stony asteroid and slow rotator, [11] classified as a near-Earth object and potentially hazardous asteroid of the Apollo asteroid and Alinda asteroid groups,[ citation needed ] approximately 2.5 kilometers in diameter. Discovered by French astronomer Christian Pollas at Caussols in 1989, the asteroid was named after Toutatis from Celtic mythology. [1] [2]
Toutatis is also a 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. [12] In December 2012, Toutatis passed within about 18 lunar distances of Earth. The Chinese lunar probe Chang'e 2 flew by the asteroid at a distance of 3.2 kilometers and a relative velocity of 10.73 km/s. [13] Toutatis approached Earth again in 2016, but will not make another notably close approach until 2069. [14]
Toutatis was first sighted on 10 February 1934, as object 1934 CT, but lost soon afterwards. [15] It remained a lost asteroid for several decades until it was rediscovered on 4 January 1989 by French astronomer Christian Pollas, and was named after the Celtic god of tribal protection Toutatis (Teutates). The name of this god is very familiar in France due to the catchphrase Par Toutatis! by the Gauls in the comics Asterix. [16]
The spectral properties suggest that this is an S-type, or stony asteroid, consisting primarily of silicates. It has a moderate Bond albedo of 0.13. [3] 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 (a contact binary), 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. [17] The asteroid may have lost most of its original angular momentum and entered into this tumbling motion as a result of the YORP effect. [18]
With a semimajor axis of 2.5294 AU, or roughly 2.5 times the distance between Earth and the Sun, Toutatis has a 3:1 orbital resonance with Jupiter and a near-1:4 resonance with Earth making it a member of the Alinda asteroid group. [12] [19] It thus completes one orbit around the Sun for every 4.02 annual orbits of Earth. The gravitational perturbations caused by frequent close approaches to the terrestrial planets lead to chaotic behavior in the orbit of Toutatis, [20] making precise long-term predictions of its location progressively inaccurate over time. [20] Estimates in 1993 put the Lyapunov time horizon for predictability at around 50 years, [20] 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. [20] The initial observations that showed its chaotic behavior were made by Wiśniewski. [21]
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 Toutatis. Earth did this in January 2009, July 2012, July 2016 and 2020. [22]
Close approaches [14] | ||
---|---|---|
Year | AU | LD |
1985 | 0.28 | 109 |
1988 | 0.12 | 45 |
1992 | 0.02 | 9 |
1996 | 0.03 | 14 |
2000 | 0.07 | 29 |
2004 | 0.01 | 4 |
2008 | 0.05 | 20 |
2012 | 0.05 | 18 |
2016 | 0.25 | 98 |
2065 | 0.36 | 142 |
2069 | 0.02 | 8 |
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). [3] The approach on 29 September 2004 was particularly close, at 0.0104 AU [23] (within 4 lunar distances) from Earth, presenting a good opportunity for observation, with Toutatis having an apparent magnitude of 8.8 at its brightest. [9] A close approach of 0.0502 AU (7,510,000 km ; 4,670,000 mi ) happened on 9 November 2008. [14] [23] The most recent close approach was on 12 December 2012, at a distance of 0.046 AU (6,900,000 km; 4,300,000 mi), [14] [23] with a magnitude of 10.7. [24] At magnitude 10.7, Toutatis was not visible to the naked eye, but just visible to experienced observers using high-end binoculars. During the 2012 encounter Toutatis was recovered on 21 May 2012, by the Siding Spring Survey at apparent magnitude 18.9. [25] A close approach will be 5 November 2069, at 0.01985 AU (2,970,000 km). [14]
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. [14] With an uncertainty parameter of 0, [3] the orbit of Toutatis is very well determined for the next few hundred years. [14] The probability of the orbit intersecting Earth is essentially zero for at least the next six centuries. [26] The likelihood of collision in the distant future is considered to be very small. [27] 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 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. [28]
In 2006 Toutatis came closer than 2 AU to Jupiter; its orbit lies inside of Jupiter's. [14] In the 2100s, it will approach Jupiter many times at a similar distance. [14]
PHA | Date | Approach distance (lunar dist.) | Abs. mag ( H ) | Diameter (C) (m) | Ref (D) | ||
---|---|---|---|---|---|---|---|
Nomi- nal(B) | Mini- mum | Maxi- mum | |||||
(33342) 1998 WT24 | 1908-12-16 | 3.542 | 3.537 | 3.547 | 17.9 | 556–1795 | data |
(458732) 2011 MD5 | 1918-09-17 | 0.911 | 0.909 | 0.913 | 17.9 | 556–1795 | data |
(7482) 1994 PC1 | 1933-01-17 | 2.927 | 2.927 | 2.928 | 16.8 | 749–1357 | data |
69230 Hermes | 1937-10-30 | 1.926 | 1.926 | 1.927 | 17.5 | 668–2158 | data |
69230 Hermes | 1942-04-26 | 1.651 | 1.651 | 1.651 | 17.5 | 668–2158 | data |
(137108) 1999 AN10 | 1946-08-07 | 2.432 | 2.429 | 2.435 | 17.9 | 556–1795 | data |
(33342) 1998 WT24 | 1956-12-16 | 3.523 | 3.523 | 3.523 | 17.9 | 556–1795 | data |
(163243) 2002 FB3 | 1961-04-12 | 4.903 | 4.900 | 4.906 | 16.4 | 1669–1695 | data |
(192642) 1999 RD32 | 1969-08-27 | 3.627 | 3.625 | 3.630 | 16.3 | 1161–3750 | data |
(143651) 2003 QO104 | 1981-05-18 | 2.761 | 2.760 | 2.761 | 16.0 | 1333–4306 | data |
2017 CH1 | 1992-06-05 | 4.691 | 3.391 | 6.037 | 17.9 | 556–1795 | data |
(170086) 2002 XR14 | 1995-06-24 | 4.259 | 4.259 | 4.260 | 18.0 | 531–1714 | data |
(33342) 1998 WT24 | 2001-12-16 | 4.859 | 4.859 | 4.859 | 17.9 | 556–1795 | data |
4179 Toutatis | 2004-09-29 | 4.031 | 4.031 | 4.031 | 15.3 | 2440–2450 | data |
2014 JO25 | 2017-04-19 | 4.573 | 4.573 | 4.573 | 17.8 | 582–1879 | data |
(137108) 1999 AN10 | 2027-08-07 | 1.014 | 1.010 | 1.019 | 17.9 | 556–1795 | data |
(35396) 1997 XF11 | 2028-10-26 | 2.417 | 2.417 | 2.418 | 16.9 | 881–2845 | data |
(154276) 2002 SY50 | 2071-10-30 | 3.415 | 3.412 | 3.418 | 17.6 | 714–1406 | data |
(164121) 2003 YT1 | 2073-04-29 | 4.409 | 4.409 | 4.409 | 16.2 | 1167–2267 | data |
(385343) 2002 LV | 2076-08-04 | 4.184 | 4.183 | 4.185 | 16.6 | 1011–3266 | data |
(52768) 1998 OR2 | 2079-04-16 | 4.611 | 4.611 | 4.612 | 15.8 | 1462–4721 | data |
(33342) 1998 WT24 | 2099-12-18 | 4.919 | 4.919 | 4.919 | 17.9 | 556–1795 | data |
(85182) 1991 AQ | 2130-01-27 | 4.140 | 4.139 | 4.141 | 17.1 | 1100 | data |
314082 Dryope | 2186-07-16 | 3.709 | 2.996 | 4.786 | 17.5 | 668–2158 | data |
(137126) 1999 CF9 | 2192-08-21 | 4.970 | 4.967 | 4.973 | 18.0 | 531–1714 | data |
(290772) 2005 VC | 2198-05-05 | 1.951 | 1.791 | 2.134 | 17.6 | 638–2061 | data |
(A) List includes near-Earth approaches of less than 5 lunar distances (LD) of objects with H brighter than 18. (B) Nominal geocentric distance from the Earth's center to the object's center (Earth radius≈0.017 LD). (C) Diameter: estimated, theoretical mean-diameter based on H and albedo range between X and Y. (D) Reference: data source from the JPL SBDB, with AU converted into LD (1 AU≈390 LD) (E) Color codes: unobserved at close approach observed during close approach upcoming approaches |
Large amounts of data of Toutatis were obtained during Chang'e 2'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. [5]
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. [5]
Toutatis has been observed with radar imaging from the Arecibo Observatory and the Goldstone Solar System Radar 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. [29] 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, [30] providing data to model Toutatis's shape and spin state.
The Chinese lunar probe Chang'e 2 departed from the Sun–Earth L2 point in April 2012 [31] 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. [13] [32] [33] It took several pictures of the asteroid, revealing it to be a dusty red/orange color.
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. The namesake is 887 Alinda, discovered by Max Wolf in 1918.
2063 Bacchus, provisional designation 1977 HB, is a stony asteroid and near-Earth object of the Apollo group, approximately 1 kilometer in diameter. The contact binary was discovered on 24 April 1977, by American astronomer Charles Kowal at the Palomar Observatory in California, United States. It was named after Bacchus from Roman mythology.
1036 Ganymed, provisional designation 1924 TD, is a stony asteroid on a highly eccentric orbit, classified as a near-Earth object of the Amor group. It was discovered by German astronomer Walter Baade at the Bergedorf Observatory in Hamburg on 23 October 1924, and named after Ganymede from Greek mythology. With a diameter of approximately 35 kilometers, Ganymed is the largest of all near-Earth objects but does not cross Earth's orbit. The S-type asteroid has a rotation period of 10.3 hours. In October 2024, it is predicted to approach Earth at a distance of 56,000,000 km; 35,000,000 mi (0.374097 AU).
6489 Golevka is an Apollo, Mars-crosser, and Alinda asteroid discovered in 1991 by Eleanor F. Helin.
(53319) 1999 JM8 is an asteroid, slow rotator and tumbler, classified as a near-Earth object and potentially hazardous asteroid (PHA) of the Apollo group, approximately 7 kilometers (4 miles) in diameter, making it the largest PHA known to exist. It was discovered on 13 May 1999, by astronomers of the Lincoln Near-Earth Asteroid Research at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico.
(33342) 1998 WT24 is a bright, sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid (PHA) of the Aten group, located in Venus's zone of influence that has frequent close encounters with Mercury, Venus, and Earth. It made a close approach to Earth on 11 December 2015, passing at a distance of about 4.2 million kilometers (2.6 million miles, 11 lunar distances) and reaching about apparent magnitude 11.
3752 Camillo is an inclined contact-binary asteroid, classified as near-Earth object of the Apollo group, approximately 2.3 kilometers in diameter. It was discovered on 15 August 1985, by astronomers Eleanor Helin and Maria Barucci using a 0.9-metre (35 in) telescope at the CERGA Observatory in Caussols, France. Lightcurve studies by Petr Pravec in 1998 suggest that the assumed S-type asteroid has an elongated shape and a longer-than average rotation period of 38 hours.
2007 TU24 is an Apollo near-Earth asteroid that was discovered by the Catalina Sky Survey in Arizona on 11 October 2007. Imaging radar has estimated that it is 250 meters (820 ft) in diameter. The asteroid passed 554,209 kilometer (344,370 mile or 1.4-lunar distance) from Earth on 29 January 2008 at 08:33 UTC. (At the time of the passage it was believed the closest for any known potentially hazardous asteroid (PHA) of this size before 2027, but in 2010 2005 YU55 was measured to be 400 meters in diameter.) At closest approach the asteroid had an apparent magnitude of 10.3 and was about 50 times fainter than the naked eye can see. It required about a 3-inch (76 mm) telescope to be seen.
(153591) 2001 SN263 is a carbonaceous trinary asteroid, classified as near-Earth object and former potentially hazardous asteroid of the Amor group, approximately 2.6 kilometers (1.6 miles) in diameter. It was discovered by the Lincoln Near-Earth Asteroid Research project at Lincoln Lab's Experimental Test Site in Socorro, New Mexico, on 20 September 2001. The two synchronous minor-planet moons measure approximately 770 and 430 meters and have an orbital period of 16.46 and 150 hours, respectively.
3122 Florence is a stony trinary asteroid of the Amor group. It is classified as a near-Earth object and potentially hazardous asteroid. It measures approximately 5 kilometers in diameter. It orbits the Sun at a distance of 1.0–2.5 AU once every 2 years and 4 months ; the orbit has an eccentricity of 0.42 and an inclination of 22° with respect to the ecliptic. Florence has two moons.
1915 Quetzálcoatl, provisional designation 1953 EA, is a very eccentric, stony asteroid classified as near-Earth object, about half a kilometer in diameter. It was discovered on 9 March 1953, by American astronomer Albert George Wilson at Palomar Observatory, California. It was named for Quetzalcoatl from Aztec mythology.
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, and conducted research from a 100-km-high lunar orbit in preparation for the December 2013 soft landing by the Chang'e 3 lander and rover. Chang'e 2 was similar in design to Chang'e 1, although it featured some technical improvements, including a more advanced onboard camera. Like its predecessor, the probe was named after Chang'e, an ancient Chinese moon goddess.
(308635) 2005 YU55, provisionally named 2005 YU55, is a potentially hazardous asteroid 360±40 meters in diameter, as measured after its Earth flyby. Previously it was estimated to be 310 meters or about 400 m (1,300 feet) in diameter. It was discovered on 28 December 2005 by Robert S. McMillan at Steward Observatory, Kitt Peak. On 8 November 2011 it passed 0.85 lunar distances (324,900 kilometers; 201,900 miles) from Earth.
(192642) 1999 RD32, provisional designation: 1999 RD32, is an asteroid and suspected contact binary on an eccentric orbit, classified as a large near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 5 kilometers (3 miles) in diameter. It was discovered on 8 September 1999, at a magnitude of 18, by astronomers of the LINEAR program using its 1-meter telescope at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, United States. The asteroid is likely of carbonaceous composition and has a rotation period of 17.08 hours.
2014 HQ124 is a sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Aten group, approximately 400 meters (1,300 feet) in diameter. It passed 3.25 lunar distances (LD) from Earth on 8 June 2014. It was discovered on 23 April 2014 by NEOWISE. It is estimated that an impact event would have had the energy equivalent of 2,000 megatons of TNT and would have created a 5 km (3 mi) impact crater. The news media misleadingly nicknamed it The Beast. 2014 HQ124 previously passed this close to Earth in 1952 and will not again until at least 2307. Radar imaging suggests it may be a contact binary.
2012 TC4 is a tumbling micro-asteroid classified as a bright near-Earth object of the Apollo group, approximately 10 meters (30 feet) in diameter. It was first observed by Pan-STARRS at Haleakala Observatory on the Hawaiian island of Maui, in the United States. As of 1 October 2017, it had a small Earth minimum orbital intersection distance of 0.000149 AU (22,300 km). On 12 October 2017, it passed Earth at 0.00033524 AU (50,151 km). The asteroid was removed from the Sentry Risk Table on 16 October 2017 and with a 5-year observation arc has a well-known orbit. For example, on the previously risk-listed date of 12 October 2022, it is now known that the asteroid will be more than 3 AU (450 million km) from Earth.
(85989) 1999 JD6 is an Aten asteroid, near-Earth object, and potentially hazardous object in the inner Solar System that makes frequent close approaches to Earth and Venus. On the Earth approach in 2015, it was observed by the Goldstone Solar System Radar and found to be a contact binary with the largest axis approximately 2 kilometers wide, and each lobe about 200–300 meters large. Although 1999 JD6 in its current orbit never passes closer than 0.047 AU to Earth, it is listed as a potentially hazardous object because it is large and might pose a threat in the future.
(153201) 2000 WO107 is a sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Aten group with a very well determined orbit. It was discovered on 29 November 2000, by astronomers of the Lincoln Near-Earth Asteroid Research (LINEAR) at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States. It is a contact binary.
2015 TB145 is a sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 650 meters (2,000 feet) in diameter. It safely passed 1.27 lunar distances from Earth on 31 October 2015 at 17:01 UTC, and passed by Earth again in November 2018.
460P/PanSTARRS (also known with the provisional designation P/2016 BA14) is a near-Earth object and periodic comet of the Jupiter family, with an orbital period of 5.25 years. In March 2016 it passed at distance of 2.2 million miles (3.5 million km, or 9 lunar distances) from Earth. It was the closest approach by a comet since 1770 and 3rd closest recorded comet to Earth. The close flyby enabled the size of the nucleus to be calculated at about 1 km (0.62 mi) in diameter, which was much bigger than expected. The comet is very dark, reflecting about 2-3 percent of the visible light, about the same as a charcoal briquette. It has a very similar orbit as numbered comet 252P/LINEAR, and may be related to it (e.g. split off of).