299 Thora

Orbital diagram
Discovery
Discovered by	Johann Palisa
Discovery date	6 October 1890
Designations
MPC designation	(299) Thora
Named after	Thor
Alternative designations	A890 TA, 1935 PC 1939 PK
Minor planet category	Main belt
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	83.21 yr (30393 d)
Aphelion	2.58 AU (386.69 Gm)
Perihelion	2.28 AU (341.48 Gm)
Semi-major axis	2.43 AU (364.09 Gm)
Eccentricity	0.062093
Orbital period (sidereal)	3.80 yr (1,386.8 d)
Mean anomaly	40.9107°
Mean motion	0° 15m 34.52s / day
Inclination	1.60383°
Longitude of ascending node	241.531°
Argument of perihelion	150.672°
Physical characteristics
Dimensions	17.06±1.5 km[1]
Synodic rotation period	274 h (11.4 d)[1]
Geometric albedo	0.1673±0.033[1]
Absolute magnitude (H)	11.3[1]

Thora (minor planet designation: 299 Thora) is a 17 km Main belt asteroid with a potentially long 274-hour rotation period.^[1] It was discovered by Johann Palisa on 6 October 1890 in Vienna.

This object has a very low rate of spin, requiring 11.37 ± 0.04 days (272.9 ± 0.9 h) to complete a full rotation.^[2]