279 Thule

This asteroid orbits the Sun at a distance of 4.35 au (651 Gm), with an eccentricity of 0.026 and an orbital period of 9.07 years. The orbital plane is inclined at an angle of 2.32° to the plane of the ecliptic. Thule was the first asteroid discovered with a semi-major axis greater than 4 AU. It is the only large asteroid with a 4:3 resonance orbital with Jupiter that also has a small eccentricity and orbital inclination.

279 Thule is classified as a D-type asteroid and is probably composed of organic-rich silicates, carbon and anhydrous silicates. Based on infrared measurements, it spans a diameter of approximately 115 km.

Thule asteroids

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. 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.