Pluto and Charon are locked in a cosmic dance

Pluto's largest moon, Charon, is tidally locked to Pluto, meaning they always show the same face to each other. This cosmic duet, confirmed by the New Horizons spacecraft in 2015, results from billions of years of gravitational tug-of-war. Uniquely, Pluto is also tidally locked to Charon, creating a rare binary system where their shared center of mass lies outside Pluto itself. This mutual embrace stabilizes their orbits and even influences Charon's geology, possibly forming its vast canyons. From Pluto, Charon would appear motionless in the sky, a permanent companion.