Titan is drifting away from Saturn 100 times faster than scientists’ predictions
The Saturnian moon’s orbit around the planet is getting farther away faster than previously predicted: 100 times faster than scientists expected. According to a new study, Saturn’s largest moon Titan was “born” fairly close to the planet, but over the course of 4.5 billion years, it has migrated out to where it orbits currently, approximately 746,000 miles (1.2 million kilometres) away from the planet. “Most prior work had predicted that moons like Titan or Jupiter’s moon Callisto were formed at an orbital distance similar to where we see them now,” Jim Fuller, assistant professor of theoretical astrophysics at Caltech and co-author on the new study. “This implies that the Saturnian moon system, and potentially its rings, have formed and evolved more dynamically than previously believed.”
Moons exert a small gravitational pull on the planets they orbit, tugging at the planet. This gravitational interaction is what causes tides in the oceans here on Earth. On our planet, friction inside of Earth from this tugging creates heat, which alters the planet’s gravitational field. This gradually pushes the moon farther away from Earth, about 1.5 inches (3.8 centimetres) every year. Titan tugs on Saturn in a similar way, but the friction inside of Saturn is thought to be weaker than here on Earth because of the planet’s gaseous composition (compared to Earth’s rocky nature). Previous research has suggested that the moon should be moving away from Saturn at just 0.04 inches (0.1 cm) per year. But this new work suggests that Titan is actually moving away from its planet at a whopping 4.3 inches (11 cm) every year.