Titan, Saturn’s largest moon, passes in front of the ringed planet in this iconic photo from NASA’s Cassini spacecraft. New research shows cloud-shrouded moon is moving about 11 centimetres (4 inches) farther from Saturn each year, 100 times faster than previously understood. Image: NASA/JPL-Caltech/Space Science Institute
Just as our own Moon floats away from Earth a tiny bit more each year, other moons are doing the same with their host planets. As a moon orbits, its gravity pulls on the planet, causing a temporary bulge in the planet as it passes.
Over time, the energy created by the bulging and subsiding transfers from the planet to the moon, nudging it farther and farther out. Our Moon drifts 1.5 inches (3.8 centimetres) from Earth each year.
Scientists thought they knew the rate at which the giant moon Titan is moving away from Saturn, but they recently made a surprising discovery: Using data from NASA’s Cassini spacecraft, they found Titan drifting a hundred times faster than previously understood – about 4 inches (11 centimetres) per year.
The findings may help address an age-old question. While scientists know that Saturn formed 4.6 billion years ago in the early days of the solar system, ...