I do not often look towards the sky. I live in Los Angeles now and before that New York City. In both places, the heavens contain little beyond light pollution captured in the orange glow of low lying clouds. Not that I mind. I am not one of those people who bemoans humans’ departure from nature. Better to leave Her well enough alone and confine ourselves to dense urban areas, preferably powered by renewable energy, of course.
But there are moments when I am taken aback by the discoveries of those who look into to the stars for a living, and I am reminded why they are called the heavens in the first place, filled as they are by mystery and wonder. Such was the feeling I had recently when reading about Neptune’s dancing moons of Thalassa and Naiad.
Discovered in 1989, these tiny orbital bodies were aptly named by their first viewers before they even knew what made them extraordinary. Naiad, which hews slightly closer to Neptune than her sister, is named for the female spirits in Greek mythology who preside over bodies of fresh water. Thalassa is the Greek primeval spirit of the sea who gave birth to the storm gods as well as the tribes of fish.
But unlike other moons with steady orbits that pull them around their planets with regularity, Thalassa and Naiad are forever engaged in a celestial dance around that blue planet named for the Roman god of the sea. Naiad’s orbit is slightly tilted compared with that of Thalassa. Pulled and pushed not only by its planet, but also that of its dance partner, Naiad oscillates over and under Thalassa twice along its orbit in a pattern known as orbital resonance.