One Planet, Two Stars, With Laurance Doyle

Episode Summary

Executive Summary: This episode covers NASA and Planetary Society news, then focuses on the landmark discovery of Kepler-16b, the first confirmed planet in a binary star system. The discussion highlights its unusual orbit, the science behind its detection, and how it challenges planet-formation theories. Lawrence Doyle also outlines a new project using animal communication studies and information theory to help design a future SETI “intelligence filter.”

Main Topics: Emily Lakdawalla’s Vandenberg launch experience: Emily recounts watching a nighttime Delta II launch from Vandenberg, emphasizing the visual spectacle, launch photography, and the significance of the final Delta II flight. Bill Nye’s outreach trip and Planetary Society update: Bill describes visiting SEDS students in Boulder and receiving a science education award in New Orleans, while promoting the Society’s Space Geek campaign and Matt Kaplan’s upcoming full-time role. Kepler-16b discovery in a binary star system: Lawrence Doyle explains the first confirmed circumbinary planet, its Saturn-like mass, near-circular orbit, and the fact that it produces double sunsets. Implications for planet formation theory: The discovery forces theorists to reconsider models of how planets form in binary systems, since Kepler-16b’s alignment suggests a very orderly protoplanetary disk. Science fiction comparison: Tatooine and Nightfall: The conversation connects the Kepler-16b discovery to Star Wars imagery and Isaac Asimov’s Nightfall, underscoring how binary and multiple-star systems expand the possibilities for strange worlds. Animal communication as a SETI analog: Doyle proposes studying communication among Earth species, using information theory and citizen science to build a framework for recognizing intelligent extraterrestrial signals. Weekly skywatch and trivia segment: Bruce Betts shares an asteroid flyby, current planetary observing notes, and the show’s trivia question and answer, wrapping the episode in the usual outreach format.

Key Arguments: Kepler-16b is the first confirmed planet found orbiting two stars, validating a long-speculated class of planets. Although not habitable, Kepler-16b is scientifically valuable because its orbit is unusually circular and exquisitely aligned with the binary system. Binary-star planets can still form despite earlier doubts; the system’s precision argues that some protoplanetary disks may form in a relatively undisturbed way. The discovery will force theorists to refine or overturn existing models of planet formation around binary stars. Studying animal communication on Earth can inform the search for extraterrestrial intelligence by defining what intelligent, complex signaling looks like. Information theory provides a quantitative way to compare communication systems across species and potentially build a SETI signal filter. Citizen science could help classify animal sonograms and scale the communication-analysis project to home computers.

Data Points: Delta II launches: 151 - Emily notes that the Vandenberg mission she watched was the last Delta II launch on the manifest after 151 launches. Launch time: around 3 a.m. - Emily describes the nighttime launch at Vandenberg. Launch pad distance: 3-4 kilometers - Emily says the launch pad was visible from several kilometers away. Kepler-16b mass: Saturn mass - Lawrence Doyle describes the planet’s approximate mass. Kepler-16b composition: half rock and half gas - Doyle characterizes the planet’s make-up. Habitable zone status: just outside the habitable zone - Doyle says the planet is not habitable and lies just beyond the system’s habitable zone. Orbital inclination alignment: within one-third of a degree - The planet’s orbit is nearly aligned with the stars’ orbital plane. Kepler-16b orbital shape: more circular than Earth’s orbit - Doyle emphasizes how circular the planet’s orbit is. Binary-star prevalence: half the stars are double stars - Doyle cites the rough prevalence of binary stars in the galaxy. Eclipsing double stars: 1 in 70 - Doyle estimates the fraction of stars that are eclipsing binaries. Transit return time: about 24 years - Doyle says Kepler-16b’s transits will disappear and then return after roughly 24 years. Asteroid flyby date: November 8 - Bruce Betts mentions asteroid 2005 YU55’s close pass by Earth. Asteroid size: 400 meters - Betts describes the asteroid as a big object that could cause serious regional destruction if it hit. Asteroid brightness: 11th magnitude - Betts notes it will only be visible with a telescope. Mars and Mercury surface gravity: about 30% of Earth’s - Betts gives the comparison during the skywatch segment.

Pivotal Quotes: "I would say it's two-thirds of a Tatooine system." — Lawrence Doyle: He answers the Star Wars comparison while explaining Kepler-16b’s double-sunset environment. "The stars are changing their distance from the planet." — Lawrence Doyle: He explains why the circumbinary habitable zone is more complex than around a single star. "If we're going to detect an extraterrestrial communication from space, then we should understand all the communication systems on Earth." — Lawrence Doyle: He introduces his project on animal communication as a SETI analog.

Implications: Kepler-16b expands the known landscape of planetary systems and will pressure formation models to adapt. Doyle’s animal-communication work could also help SETI identify nonrandom intelligence signatures in future signals.