279 Thule

This article is about the main-belt asteroid. For the Kuiper belt object once nicknamed Ultima Thule, see 486958 Arrokoth.

279 Thule is a large asteroid from the outer asteroid belt. It is classified as a D-type asteroid and is probably composed of organic-rich silicates, carbon and anhydrous silicates. Thule was the first asteroid discovered with a semi-major axis greater than 4 AU. It was discovered by Johann Palisa on 25 October 1888 in Vienna and was named after the ultimate northern land of Thule.

279 Thule

Orbital diagram
Discovery
Discovered by	Johann Palisa
Discovery date	25 October 1888
Designations
MPC designation	(279) Thule
Pronunciation	/ˈθjuːliː/[1]
Alternative designations	A888 UA, 1920 GA 1923 RA, 1927 EC 1954 FF[2]
Minor planet category	Asteroid belt (Thule)
Adjectives	Thulean /ˈθjuːliən/[3]
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	125.34 yr (45780 d)
Aphelion	4.4617880 AU (667.47398 Gm)
Perihelion	4.2367660 AU (633.81117 Gm)
Semi-major axis	4.3492770 AU (650.64258 Gm)
Eccentricity	0.025869
Orbital period (sidereal)	9.07 yr (3313.0 d)
Mean anomaly	62.75874°
Mean motion	0° 6m 31.184s / day
Inclination	2.323774°
Longitude of ascending node	72.46791°
Argument of perihelion	42.36797°
Physical characteristics
Dimensions	126.59±3.7 km (IRAS)[2]
Synodic rotation period	23.896 h (0.9957 d)[2]
Geometric albedo	0.0412±0.003[2]
Temperature	133 K
Spectral type	B−V=0.75[2] U−B=0.32[2] D (Tholen)[2] X (SMASSII)[2]
Absolute magnitude (H)	8.57[2]

Thule asteroids

See also: Minor-planet groups out to Jupiter

Thule was the first discovered member of the Thule dynamical group, which as of 2008 was known to consist of three objects: 279 Thule, (186024) 2001 QG207, and (185290) 2006 UB219.^[4] The orbits of these bodies are unusual. They orbit in the outermost edge of the asteroid belt in a 4:3 orbital resonance with Jupiter, the result of the periodic force Jupiter exerts on a body with Thule's orbital period, in the same way (though with the reverse effect) as the Kirkwood gaps in the more inner parts of the asteroid belt.

Known members as of May 2021^{[5][better source needed]}

Name	semimajor axis (au)	period (years)	eccentricity	inclination (°)	absolute magnitude	Size (km)
279 Thule	4.269	8.82	0.0432	2.334	8.53	126.59±3.7
(185290) 2006 UB219	4.290	8.89	0.1335	7.132	13.84	4.1–10.1
(186024) 2001 QG207	4.278	8.85	0.2513	3.238	14.53	3.0–7.4
(570461) 2006 SJ42	4.286	8.87	0.0465	5.501	15.1	2.3–5.7
(684250) 2008 RE93	4.288	8.88	0.1161	3.497	15.49	1.9–4.7
(654117) 2014 WN504	4.297	8.91	0.2312	3.193	15.5	1.9–4.7
2014 QX231	4.283	8.86	0.3722	5.935	16.5	1.2–3.0

See also

• 486958 Arrokoth – A cubewano that was formerly nicknamed Ultima Thule