Orbit
Ceres follows an orbit between Mars and Jupiter, within the asteroid belt, with a period of 4.6 Earth years. The orbit is moderately inclined (i = 10.6° compared to 7° for Mercury and 17° for Pluto) and moderately eccentric (e = 0.08 compared to 0.09 for Mars).
The diagram illustrates the orbits of Ceres (blue) and several planets (white and grey). The segments of orbits below the ecliptic are plotted in darker colours, and the orange plus sign is the Sun's location. The top left diagram is a polar view that shows the location of Ceres in the gap between Mars and Jupiter. The top right is a close-up demonstrating the locations of the perihelia (q) and aphelia (Q) of Ceres and Mars. The perihelion of Mars is on the opposite side of the Sun from those of Ceres and several of the large main-belt asteroids, including 2 Pallas and 10 Hygiea. The bottom diagram is a side view showing the inclination of the orbit of Ceres compared to the orbits of Mars and Jupiter.
| Element type |
a (in AU) |
e | i | Period (in days) |
|---|---|---|---|---|
| Proper | 2.7671 | 0.116198 | 9.647435 | 1681.60 |
| Osculating (Epoch 2010-Jul-23) |
2.7653 | 0.079138 | 10.586821 | 1679.66 |
| Difference | 0.0018 | 0.03706 | 0.939386 | 1.94 |
In the past, Ceres had been considered to be a member of an asteroid family. These groupings of asteroids share similar proper orbital elements, which may indicate a common origin through an asteroid collision some time in the past. Ceres was found to have spectral properties different from other members of the family, and so this grouping is now called the Gefion family, named after the next-lowest-numbered family member, 1272 Gefion. Ceres appears to be merely an interloper in its own family, coincidentally having similar orbital elements but not a common origin.
The rotational period of Ceres (the Cererian day) is 9 hours and 4 minutes.
Ceres is in a near-1:1 mean-motion orbital resonance with Pallas (their orbital periods differ by 0.3%). However, a true resonance between the two would be unlikely; due to their small masses relative to their large separations, such relationships among asteroids are very rare.
Read more about this topic: Ceres (dwarf Planet)
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