1866 Sisyphus

1866 Sisyphus
Discovery
Discovered by	P. Wild
Discovery site	Zimmerwald Obs.
Discovery date	5 December 1972
Designations
MPC designation	(1866) Sisyphus
Pronunciation	/ˈsɪsɪfəs/
Named after	Σίσυφος Sīsyphos (Greek mythology)
Alternative designations	1972 XA
Minor planet category	Apollo; NEO; Mars-crosser;
Adjectives	Sysiphean /sɪsɪˈfiːən/, Sisyphian /sɪˈsɪfiən/
Orbital characteristics
	Epoch 4 September 2017 (JD 2458000.5)
	Uncertainty parameter 0
Observation arc	61.55 yr (22,482 days)
Earliest precovery date	26 January 1955
Aphelion	2.913 AU (435.8 Gm)
Perihelion	0.8747312 AU (130.85792 Gm)
Semi-major axis	1.8936992 AU (283.29337 Gm)
Eccentricity	0.5386
Orbital period (sidereal)	2.61 yr (952 days)
Mean anomaly	85.918°
Mean motion	0° 22m 41.88s / day
Inclination	41.202°
Longitude of ascending node	63.498°
Argument of perihelion	293.09°
Known satellites	1; (Orbital period of 27.16±0.05 h)
Earth MOID	0.1045 AU (15.63 Gm)
Mars MOID	0.1291 AU (19.31 Gm)
Physical characteristics
Dimensions	5.72±0.07 km; 6.597±0.189 km; 6.859 km; 6.86 km (taken); 8 km; 8.48 km; 8.9 km;
Synodic rotation period	2.3909±0.0004 h; 2.400 h; 2.4 h; 2.401±0.001 h; 2.424±0.001 h; 2.7 h;
Geometric albedo	0.14; 0.15; 0.19±0.07; 0.255±0.049; 0.360±0.010; 0.3719;
Spectral type	SMASS = S; S;
Apparent magnitude	9.0 (discovery) 9.3 (2071 close approach)
Absolute magnitude (H)	11.7±0.2 (R); 12.4; 12.51±0.149; 13.0;

1866 Sisyphus /ˈsɪsɪfəs/ is a binary stony asteroid, near-Earth object and the largest member of the Apollo group, approximately 7 kilometers in diameter.

It was discovered on 5 December 1972, by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland, and given the provisional designation 1972 XA. It was named after Sisyphus from Greek mythology.