209 Dido

209 Dido is a main-belt asteroid with a diameter of 179±1 km.^[4] It was discovered by C. H. F. Peters on October 22, 1879, in Clinton, New York and was named after the mythical Carthaginian queen Dido. This asteroid is orbiting the Sun at a distance of 3.15 AU with an eccentricity (ovalness) of 0.058 and a period of 5.59 yr. The orbital plane is tilted at an angle of 7.2° to the plane of the ecliptic.^[4]

209 Dido

Discovery
Discovered by	C. H. F. Peters
Discovery date	22 October 1879
Designations
MPC designation	(209) Dido
Pronunciation	/ˈdaɪdoʊ/[1]
Named after	Dido
Alternative designations	A879 UC, 1909 AB 1909 GB, 1912 RB
Minor planet category	Main belt
Adjectives	Didonian /daɪˈdoʊniən/[2][3]
Orbital characteristics[4]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	136.47 yr (49,845 d)
Aphelion	3.331 AU (498.3 Gm)
Perihelion	2.968 AU (444.1 Gm)
Semi-major axis	3.150 AU (471.2 Gm)
Eccentricity	0.057565
Orbital period (sidereal)	5.59 yr (2,040.5 d)
Average orbital speed	16.79 km/s
Mean anomaly	311.722°
Mean motion	0° 10m 34.738s / day
Inclination	7.16997°
Longitude of ascending node	0.682681°
Argument of perihelion	248.387°
Physical characteristics
Dimensions	179±1 km[4] 140.35±10.12 km[5]
Mass	(4.59±7.42)×1018 kg[5]
Synodic rotation period	5.737 h (0.24 d)[4][6]
Geometric albedo	0.028±0.004
Spectral type	C
Absolute magnitude (H)	8.24

3D convex shape model of Dido

209 Dido is classified as a C-type asteroid and is probably composed of carbonaceous materials. Like many asteroids of its type, it has an extremely low albedo. Photometric observations at the Palmer Divide Observatory during 2005 showed a rotation period of 5.7366±0.0005 hours with a brightness variation of 0.17±0.02 in magnitude.^[6] The pole orientation in ecliptic coordinates, as determined from multiple light curve studies, is (β_p, λ_p) = (120°±6°, 66°±7°).^[7]

209 Dido has been observed to occult 4 stars between 2005 and 2023.