Jacques Laskar

Jacques Laskar ( born April 28, 1955 in Paris ) is a French astronomer, known for celestial mechanics studies, the evidence of chaotic behavior in the solar system services.

Laskar studied from 1974 to 1977 at the École Normale Supérieure de Cachan Mathematics ( diploma 1976) and then was a school teacher. In 1981, he received his aggregation in mathematics and in 1982 his DEA in astronomy and celestial mechanics at the Paris Observatory, where he received his doctorate in 1984. 1985/86 he worked as a post-doc at the Jet Propulsion Laboratory. Since 1985 he is a researcher at the CNRS at the Bureau des Longitudes, since 1994 as Director of Research at CNRS at the Paris Observatory. He runs since 1992 a celestial mechanics working group at the Observatory of Paris.

Laskar developed through extensive computer algebra calculations supported simulation methods in celestial mechanics. In 1989, he simulated the solar system (excluding Pluto) over 100 million years into the future and the past, where he found signs of chaotic behavior. The time scale for the formation of chaotic behavior (according to the Lyapunov exponent ) amounts to 4 to 5 million years so that in this case, the predictions for over a few ten million years will be impossible. This long-term simulations were confirmed by Jack Wisdom and Gerald Jay Sussman 1992.

In 1993 he demonstrated the instability of the rotation axes of the inner planets Earth, Mars, Venus, Mercury. For example showed, he would that sway the earth's axis without the effect of the moon in its inclination from zero to 85 degrees, and that the inclination of the axis of rotation of Mars from zero to 60 degrees in the past fluctuated, with corresponding effects on the climate of Mars. He could also explain the retrograde rotation of Venus from passages by chaotic zones in the long-term development.

In simulations of the solar system about five billion years, which he carried out in 2008, he found evidence not only on for some time because of the resonance with Jupiter suspected possible collision of Mercury with Venus or the sun, but in a simulation even a destabilization of all the inner planets (Mercury, Venus, Earth ) in 3.3 billion years, with the possibility of collisions of the inner planets with the earth. The calculations were more accurate than previous simulations ( the averaging used ) and related general relativistic effects and the moon with a.

Laskar turned his developed in celestial mechanics, methods of frequency analysis also depends on the stability of Teilchenbeschleunigerbahnen and galactic dynamics.

In 1993 he received the IBM Award and the Prix de G. Pontécoulant the French Academy of Sciences ( Académie des sciences ). In 1994 he received the Silver Medal of the CNRS. In 1996, he gave one of the plenary on the second European Congress of Mathematicians in Budapest ( Stability of the Solar System). Since 1997 he has been corresponding since 2003 and a full member of the French Academy of Sciences. In 2007 he received the Brouwer Award of the American Astronomical Society.