A Talk by Dr. Oliver White (SETI Institute)

May 28, 2025

Ten years ago, the New Horizons spacecraft flew by the Pluto system and revealed an unexpectedly diverse range of landscapes on that dwarf planet and its largest moon Charon -- implying much more complex geological histories for these distant worlds than anyone expected. Dr. White leads a vivid tour of their often bizarre terrains, some of which are still evolving, and explains what processes scientists think molded them into their present appearances. After a brief stop at Pluto's four small moons, Dr. White extends the tour 2 billion km farther out into space, to show us Arrokoth, the tiny "planetesimal" that New Horizons flew past three and a half years after visiting Pluto. It is the most primitive object in the Solar System ever visited by a spacecraft.

Non-technical Talk by Prof. Jonathan Fortney (U. of California, Santa Cruz)
Apr. 9, 2025

Over 6000 planets have now been found around other stars, but we only have information about what their atmospheres are like for a few dozen. NASA's powerful James Webb Space Telescope (JWST), which features a 20-foot mirror in space, is currently being used to understand planetary atmospheres. Prof. Fortney explains how we can look for atmospheres around rocky planets the size of the Earth, and how his group and others are already measuring the abundances of molecules like water, methane, ammonia, and carbon dioxide in the atmospheres of larger planets, of sizes similar to Neptune and Jupiter. And he tells us what astronomers are looking forward to in the next year or two with JWST.

Mar. 5, 2025

Dr. Simon Steel (SETI Institute)

Dr. Steel discusses the Copernican revolution and how it changed humanity's view of its place in the universe. He then talked about other "Copernican" discoveries that displaced us from a central perch, including the revision of our place in the Galaxy, the discovery of other galaxies, and now our finding a remarkable number of planets (including Earth-like planets) orbiting other stars. He explains how such discoveries give context for, and have prepared us for, the next potential Copernican revolution, the discover of intelligent life elsewhere in the cosmos. He concludes by describing some of the most exciting experiments now underway to find evidence of such life among the nearest stars and busiest galaxies. Dr. Steel is Deputy Director of the Carl Sagan Center for Research at the SETI Institute.