| Object type | Apollo near-Earth asteroid; potentially hazardous; Sk-type (stony)[1] |
|---|---|
| First seen | Feb. 10, 1934 (as 1934 CT) — then lost[2] |
| Rediscovered | Jan. 4, 1989 by Christian Pollas, Caussols, France[2] |
| Named for | Teutates/Toutatis, a Celtic tribal god[3] |
| Dimensions | ≈ 4.26 × 2.03 × 1.70 km[1] |
| Rotation | Tumbling: 5.38-day roll plus 7.38-day precession[2] |
| Geometric albedo | ≈ 0.41[1] |
| Distance from Sun | 0.955–4.13 AU[1] |
| Orbital period | ≈ 4.0 years[1] |
| Inclination | ≈ 0.45° — almost in Earth’s orbital plane[1] |
| Earth MOID | ≈ 0.0065 AU (≈ 2.5 lunar distances)[1] |
| Spacecraft | Chang’e 2 flyby, Dec. 13, 2012 — 3.2 km at 10.73 km/s[4] |
Lost for 55 years
Toutatis was first sighted on 10 February 1934 and designated 1934 CT, but it was soon lost. It stayed lost for decades until French astronomer Christian Pollas rediscovered it at Caussols on 4 January 1989.[2]
Pollas named it after Toutatis (Teutates), the Celtic god of tribal protection — a name familiar in France from the catchphrase “Par Toutatis!” in the Asterix comics.[2][3]
A world with no regular day
Most asteroids spin around one axis. Toutatis tumbles: it rolls around its long axis every 5.38 days while that axis precesses every 7.38 days. Standing on its surface, you would see the Sun rise and set at apparently random places and times.[2]
The YORP effect — the tiny torque from sunlight being absorbed and re-emitted — may have drained its spin and pushed it into this tumbling state.[2][5]
Head and body
Radar imaging showed a highly irregular body with two lobes, which may have formed when two separate bodies merged.[2] JPL gives dimensions of about 4.26 × 2.03 × 1.70 km.[1] Images from China’s Chang’e 2 confirmed that Toutatis is not a monolith but most likely a coalescence of shattered fragments, with a small “head” and a larger “body”.[2]
A chaotic orbit
Toutatis swings from just inside Earth’s orbit (0.955 AU) out to 4.13 AU, near Jupiter’s territory, every 4 years.[1] A 3:1 resonance with Jupiter, a near 1:4 resonance with Earth and frequent close passes by the inner planets make its orbit chaotic over long timescales.[2]
Its orbit is tilted less than half a degree, so it lies almost exactly in the plane of Earth’s orbit.[1]
Close approaches
Toutatis passed Earth in 1992, 1996, 2000, 2004, 2008, 2012 and 2016, and is listed as a potentially hazardous object.[2][6] On 29 September 2004 it came within about 4 lunar distances and reached magnitude 8.8.[2] Its orbit is very well determined, and the probability of an impact in at least the next six centuries is essentially zero. After 2016, it will not make another notably close approach until 2069.[2]
Build your own spacecraft
Toutatis is one of only a handful of asteroids imaged up close by a spacecraft. If you like holding your science, our model kit picker suggests rocket, spacecraft and solar-system kits by builder age and budget.
Read more
Chang’e 2 and the 2012 Toutatis flyby
A lunar orbiter that went on to visit L2 and then made China’s first asteroid encounter.
Read →Par Toutatis! A lost asteroid and a Celtic god
How an asteroid seen in 1934 was lost for decades, then found and named after a god of Gaulish tribes.
Read →Why Toutatis tumbles
Two rotations at once, sunlight torques and what “daytime” would mean on a non-principal-axis rotator.
Read →Sources
- Small-Body Database Lookup: 4179 Toutatis — NASA JPL Solar System Dynamics
- 4179 Toutatis — Wikipedia
- Teutates — Wikipedia
- Chang'e 2 — Wikipedia
- YORP effect — Wikipedia
- Potentially hazardous object — Wikipedia
- Planetary Fact Sheet (orbit comparison) — NASA NSSDCA
Figures are rounded; where sources differ we note it. Spotted an error? Tell us.