| Minorplanet: | yes |
| Bgcolour: |
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| 53 Kalypso | |
| Discoverer: | Karl Theodor Robert Luther |
| Discovered: | 4 April 1858 |
| Mpc Name: | (53) Kalypso |
| Pronounced: | [1] |
| Adjective: | Kalypsonian Kalypsoian |
| Named After: | Calypso |
| Mp Category: | Main belt |
| Epoch: | December 31, 2006 (JD 2454100.5) |
| Semimajor: | 391.903 Gm (2.620 AU) |
| Perihelion: | 311.998 Gm (2.086 AU) |
| Eccentricity: | 0.204 |
| Period: | 1548.736 d (4.24 a) |
| Inclination: | 5.153° |
| Asc Node: | 143.813° |
| Arg Peri: | 312.330° |
| Mean Anomaly: | 98.113° |
| Dimensions: | 115.4 km |
| Density: | 1.625 ± 0.653/0.517 g/cm3 |
| Rotation: | 9.036 h |
| Abs Magnitude: | 8.81 |
| Albedo: | 0.040[2] |
53 Kalypso is a large and very dark main belt asteroid that was discovered by German astronomer Robert Luther on April 4, 1858, at Düsseldorf. It is named after Calypso, a sea nymph in Greek mythology, a name it shares with Calypso, a moon of Saturn.
The orbit of 53 Kalypso places it in a mean motion resonance with the planets Jupiter and Saturn. The computed Lyapunov time for this asteroid is 19,000 years, indicating that it occupies a chaotic orbit that will change randomly over time because of gravitational perturbations of the planets.
Photometric observations of this asteroid during 2005–06 gave a light curve with a period of 18.075 ± 0.005 hours and a brightness variation of 0.14 in magnitude. In 2009, a photometric study from a different viewing angle was performed at the Organ Mesa Observatory in Las Cruces, New Mexico, yielding a rotation period of 9.036 ± 0.001 with a brightness variation of 0.14 ± 0.02 magnitude. This is exactly half of the 2005–06 result. The author of the earlier study used additional data observation that favored the 9.036 hour period. The discrepancy was deemed a consequence of viewing the asteroid from different longitudes.
Kalypso has been studied by radar.[3]