Friedman Lectures in Astronomy and Astrophysics set for April 15, 16
Alessandro Morbidelli, astronomer and planetary scientist at the Collège de France, will present the 2025 Friedman Lectures in Astronomy and Astrophysics on April 15 and 16 on the Penn State University Park campus.
The series includes a lecture intended for a general audience, titled “The Diversity of Planetary Systems: How Singular Is Our Own?” at 7 p.m. on Tuesday, April 15, in Freeman Auditorium, HUB-Robeson Center, as well as a more-specialized lecture, titled “Formation and Evolution of a Protoplanetary Disk: Combining Observations, Simulations, and Cosmochemical Constraints” at 3:45 p.m. on Wednesday, April 16, in 538 Davey Laboratory.
“The Diversity of Planetary Systems: How Singular is Our Own”
The discovery of a large number of extrasolar planets has demonstrated that our own system is not "typical.” Exoplanetary systems can be very different from our own and diverse from each other. Understanding this diversity is a major goal of modern planetary science. The formation of planetary systems is not fully understood, but major advances have been obtained in the last 20 years. New concepts have been proposed, such as the streaming instability for the formation of planetesimals and pebble accretion for the formation of the cores of giant planets. It is also now clear that planets forming in the protoplanetary disks have to migrate during their accretion if their mass exceeds a few times the mass of Mars. Accretion and dynamical evolution are therefore very coupled processes. This leads to complex evolutions, very sensitive to initial conditions and contingent events, that are the key to understanding the observed diversity of planetary systems. The early formation of Jupiter and its limited migration due to the formation of Saturn are two fundamental ingredients that determined the basic structure of the solar system. There is also evidence that the vast majority of planetary systems become unstable after the removal of the protoplanetary disk. The effects of this instability are very different depending on the masses of the planets involved. Our solar system also experienced a global instability, but fortuitously our giant planets did not develop large orbital eccentricities.
About the speaker
Alessandro Morbidelli received a master’s degree in physics at the University of Milan, Italy, in 1988 and a doctoral degree in mathematics at the University of Namur, Belgium, in 1991. In 1993, he obtained a French National Centre for Scientific Research permanent position at the Côte d'Azur Observatory, in Nice, and in 2023 was elected professor at the Collège de France — the most ancient and prestigious French academic institution — in Paris, with a chair on planet formation. He is an expert on the formation and dynamic evolution of planetary systems. He has extensively studied the formation and evolution of our solar system. In 2005, with three other colleagues all gathered in Nice, he published a trilogy of papers in the journal Nature, proposing the so-called “Nice model,” which reconstructs the evolution of the outer solar system after the removal of gas from the disk. He also studied several other aspects of the formation of planetary systems: giant planet formation and orbital migration, the effect of giant planets on the circulation of dust in the disk, planetesimal formation, super-Earth formation, etc. Morbidelli has been the recipient of a number of awards, including the Urey Prize of the Division for Planetary Science of the American Astronomical Society in 2000 and the bronze and silver medal of CNRS in 1995 and 2019. In 2021, he received an advanced grant from the European Research Council to build a new coherent model of terrestrial planet formation in the next five years. Also in 2021, he became editor in chief of the journal Icarus, a planetary science journal started in 1968 by Carl Sagan. He is a scientific adviser of the French space agency, CNES.
About the Friedman Lectures
This presentation is hosted by the Penn State Department of Astronomy and Astrophysics and is funded largely by the Ronald M. and Susan J. Friedman Outreach Fund in Astronomy. Mr. Friedman is a member of the department's board of visitors. The free, public lecture series was founded in 1998. Past talks are listed on the department’s website.