University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Thursday, March 1st 2018
4:00 pm:
Speaker: Sara Seager, MIT
Subject: Mapping the Nearest Stars for Habitable Worlds
Joint Colloquium with Earth Sciences (Nier Lecture). Note later start time.


"Sara Seager is a planetary scientist and astrophysicist at the Massachusetts Institute of Technology where she is a Professor of Planetary Science, Professor of Physics, Professor of Aerospace Engineering, and holds the Class of 1941 Professor Chair. She has pioneered many research areas of characterizing exoplanets with concepts and methods that now form the foundation of the field of exoplanet atmospheres. Her present research focus is on the search for life by way of exoplanet atmospheric “biosignature” gases. Professor Seager works on space missions for exoplanets including as: the PI of the CubeSat ASTERIA; the Deputy Science Director of the MIT-led NASA Explorer-class mission TESS; and as a lead of the Starshade Rendezvous Mission (a space-based direct imaging exoplanet discovery concept under technology development) to find a true Earth analog orbiting a Sun-like star. Among other accolades, Professor Seager was elected to the US National Academy of Sciences in 2015, is a 2013 MacArthur Fellow, is a recipient of the 2012 Sackler Prize in the Physical Sciences, and has Asteroid 9729 named in her honor."


Thousands of exoplanets are known to orbit nearby stars and small rocky planets are established to be common. The ambitious goal of identifying a habitable or inhabited world is within reach. But how likely are we to succeed? We need to first discover a pool of planets in their host star’s “extended” habitable zone and second observe their atmospheres in detail to identify the presence of water vapor, a requirement for all life as we know it. Life must not only exist on one of those planets, but the life must produce “biosignature gases” that are spectroscopically active, and we need to be able to sort through a growing list of false-positive scenarios with what is likely to be limited data. The race to find habitable exoplanets has accelerated with the realization that “big Earths” transiting small stars can be both discovered and characterized with current technology, such that the James Webb Space Telescope has a chance to be the first to provide evidence of biosignature gases. Transiting exoplanets require a fortuitous alignment and the fast-track approach is therefore only the first step in a long journey. The next step is sophisticated starlight suppression techniques for large ground-and space-based based telescopes to observe small exoplanets directly. These ideas will lead us down a path to where future generations will implement very large space-based telescopes to search thousands of all types of stars for hundreds of Earths to find signs of life amidst a yet unknown range of planetary environments. What will it take to identify such habitable worlds with the observations and theoretical tools available to us?

Nier Info:

Professor A.O. Nier

A.O. Nier served as a highly distinguished faculty member of the Physics Department for 42 years starting in 1938. He was actively involved in research up to the time of his death in 1994. A firm believer in “pursuits of knowledge - in areas which cross traditional lines” he had an enormous impact on the geological sciences by his pioneering work on isotope abundances and measurements of many elements which are used in radiometric age determinations of geologic materials. He received many national and international awards in recognition of his discoveries and contributions to Physics, Geological Sciences and many other fields.

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