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Institute of Celestial Mechanics and Ephemeris Calculation

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Institute of Celestial Mechanics and Ephemerides Calculation - UMR 8028

The laboratory conducts research in celestial mechanics and uses the astrometric observation for the exploration of the solar system. It also develops mathematical research in the field of dynamical systems.

In this page

Research activities

Applications are made in solar system dynamics.
The dynamics of the planets is modeled in the short-term for the needs of space probes, in the medium-term to publish ephemeris needed for observations and in long-term to study the evolution of the solar system. The dynamics of small solar system bodies (moons, planets, asteroids, meteor showers, comets) is designed to explore the interaction between these bodies, their evolution, their physical nature and the history of the solar system.
The astrometric observations are developed in order to adjust our models to the observed positions of objects and detect small effects, signatures of the dynamic evolution of the solar system. International observation campaigns are organized to obtain the best possible data with the highest astrometric accuracy.


dynamical systems - solar system - astrometry - celestial mechanics

Teams and research themes

The laboratory has two research teams:

- Astronomy and dynamical systems. This team focuses primarily on celestial mechanics theory. A strong component of mathematicians search special solutions to the problem of n bodies with astronomical applications. Astronomers study the dynamics of planets in the solar system and extra-solar systems in the short and long-term and fit them to their observations.

- Astrometry and Planetology Group. This team is dedicated primarily to the studying of the dynamics of small solar system objects. It is based on the astrometric observation that allows an exploration of the solar system from ground-based observatories and space. The high-precision observations provide access to tidal effects in systems of planets and their satellites, to discover binary or triple asteroids.

Active projects

Participation in the space mission project to Jupiter and Europe in the context of the ESA "Cosmic Vision" invitation to tender

Development of an analytical theory on the rotation of Titan
Study of remote satellite systems of Jupiter and Saturn: evolution and dynamics of satellite capture process

Organization of an international campaign of observation of Saturn and Jupiter satellites during the equinox of these planets in 2009

Determination of the masses of asteroids in the framework of the Gaia mission

Establishment of an Earth's environment monitoring system: determination of the orbits of NEOs asteroids and forecasts of rain showers meteor

Detection and observation of multiple asteroids

Participation in the Rosetta and Marco Polo missions

Study of the Pluto system in conjunction with the News Horizons mission to Pluto

Calibration of the geological time scale by celestial mechanics

Dynamics of extra-solar planets systems

Search of specific solutions to the problem of n bodies

Main scientific results

Demonstration of the low density of the Trojan asteroid (617) Patroclus (2006, Nature, 439, 7076, p.565)
Dynamic study of "the trio of Neptunes", the extra-solar planets system  (2006, Nature, 441, 7091, p.305)
First detection of a triple asteroid (87) Sylvia (2005, Nature, 436, 7052, 822)
First observation and identification of a meteor on Mars (2005, Nature, 435, 7042, p.581)
Astronomical calibration of the Neogene geological time scale (2004, Astr. Astrophys. 428, p.261)
Explanation of spin-orbit resonance of Mercury (2004, Nature, 429, 6994, p.848)
Demonstration of glacial cycles on Mars (2004, Nature, 431, 7012, p.1072)
Demonstration of thermal equilibrium of Io (2009, Nature, 459, 8108, p.957)

Doctoral schools

ED 127 – Astronomy and Astrophysics in Ile de France

Scientific parternships

LESIA, SYRTE and LUTH Laboratories (Observatoire de Paris)


Observatoire de Besançon, Observatoire de la Côte d'Azur


Massachussets Institute of Technology, U.S. Naval Observatory, SETI- université de Berkeley (USA), observatoire de Nanjing, observatoire du Yunnan, université de Guangzou (Chine), observatoire royal de Belgique, université de Namur (Belgique), Institut Sternberg de Moscou, observatoire de Pulkovo (Russie), observatoire de Rio de Janeiro (Brésil).

Main equipements

Equipment in computation

Main publications

French National Ephemeris: "Knowledge of the times", the "Nautical Ephemeris", the "Yearbook of the Bureau des Longitudes"

33 1 40 51 22 62
Physical address

Laboratory e-mail

Web site
Postal address
Observatoire de Paris, 77, avenue Denfert-Rochereau 75014 Paris

Communication contact
ARLOT Jean-Eudes
33 1 40 51 22 67
Administrative contact
NICOLAS Isabelle
33 1 40 51 22 79

Teachers - researchers :

Researchers :

Help staff :

Post-doctorate :

phD students :

Expanse :
850 m2