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October 12, 2005
Contact: Adrian Melott, Physics and Astronomy, (785) 864-3037

Lecture to explore relationship between early life on Earth and changing climates

LAWRENCE -- James Kasting, distinguished professor of geosciences at Pennsylvania State University, will focus on the interplay between Earth's climate and its early life in a free and public lecture, "Gaia Revisited" on Oct. 24 at the University of Kansas.

Kasting will look in particular at the rise of oxygen and the way in which life may act to "regulate" the temperature of the earth. The lecture is slated for 7:30 p.m in Alderson Auditorium, Kansas Union.

Kasting also will present a colloquium on "Habitable Zones Around Stars and the Search for Extraterrestrial Life" at 4 p.m. in Room 1001 Malott Hall. Kasting will provide information about those areas around stars where planets like Earth could sustain life. This is an important consideration in the search for life on other planets, an area of growing scientific importance.

A Harvard University graduate with two masters' degrees and a doctorate from the University of Michigan, Kasting is a former research scientist with NASA. He is the chairman of the Science Definition Team for NASA's Terrestrial Planet Finder, a mission being designed to study the light from distant stars in order to detect the existence of planets with an atmosphere supporting life similar to that on Earth. His research interests include atmospheric evolution, planetary atmospheres and paleoclimates.

At the lecture, Kasting will explain that the harvesting of light to produce energy and oxygen is the signature of all land plants. The ability was co-opted from an ancient life form called cyanobacteria. Today these bacteria, as well as microscopic algae, supply oxygen to the atmosphere and churn out usable nitrogen in Earth's oceans, Kasting has written. Microorganisms may also have played a major role in atmosphere evolution before the rise of oxygen. Under the more dim light of a young sun cooler than today's, groups of anaerobic bacteria may have been pumping out large amounts of methane, thereby keeping the early climate warm and inviting. The evolution of Earth's atmosphere is linked tightly to the evolution of its flora and fauna.

During the colloquium, Kasting will describe how the habitable zone around a star is defined as the region in which an Earth-like planet can maintain liquid water on its surface. The inner edge of the zone is determined by loss of water, while the outer edge is determined by the condensation of CO2 to form clouds and polar caps. The continuously habitable zone is the region that remains habitable for some finite period of time. This may be tested within the next 12 to15 years by NASA's proposed twin Terrestrial Planet Finder missions and may provide indirect evidence for the existence of life elsewhere in the galaxy.

The Department of Physics and Astronomy, the Department of Geology and the Astrobiology Working Group at KU will sponsor the lecture.

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