Saturn has moons like a dog has fleas , and they’re all fascinating in their own ways. This new picture from NASA’s Cassini probe shows off the peculiarity of Daphnis, a moon so tiny it wasn’t discovered until 2005. It’s just 8 kilometres (5 miles) across, and irregularly shaped, which gives it a wobbly orbit.
If it was elsewhere, maybe this would be unremarkable, but Daphnis coasts around inside Saturn’s A ring, in a space called the Keeler Gap ( here’s a diagram ). It’s also what is called a shepherd moon (named after a shepherd from Greek mythology), which is a moon that clears a gap in a planetary ring.
