- 101 Helena
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101 Helena DiscoveryDiscovered by James Craig Watson Discovery date August 15, 1868 DesignationsNamed after Helen of Troy Alternate name(s) Minor planet
categoryMain belt Epoch December 31, 2006 (JD 2454100.5) Aphelion 441.092 Gm (2.949 AU) Perihelion 331.683 Gm (2.217 AU) Semi-major axis 386.387 Gm (2.583 AU) Eccentricity 0.142 Orbital period 1516.159 d (4.15 a) Average orbital speed 18.44 km/s Mean anomaly 125.599° Inclination 10.199° Longitude of ascending node 343.471° Argument of perihelion 347.818° Physical characteristicsDimensions 65.8 km Mass 3.0×1017 kg Mean density 2.0 g/cm³ Equatorial surface gravity 0.0184 m/s² Escape velocity 0.0348 km/s Rotation period ? d Albedo ? Temperature ~173 K Spectral type S Absolute magnitude (H) 8.33 101 Helena is a fairly large, rocky main-belt asteroid. It was discovered by J. C. Watson on August 15, 1868. It is named after Helen of Troy in Greek mythology.
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