Is Earth's crustal formation influenced by its position in the galaxy? And how would we know? It's obvious there are many celestial cycles, from the earthly ones that Milankovitch described to the orbit of the solar system through the galaxy, but how can we tie those to geological planetary cycles, like the 800 m.y. resonance of the core, the 500-300 m.y. supercontinent cycle, and the ~ 30 m.y. impact cycle?  Professor Chris Kirkland and team from Australia's Curtin University have developed a zircon-based approach that they say can tease apart the cyclic secrets of crust formation. We talk radiometric dating, limits and benefits of the technique, asymptotic time horizons, and the difficulties of doing geology on a galactic scale.