Charon: the moon Pluto paints red

Curious facts

1. 01

   The biggest moon for its planet

   It is half the size of Pluto: the largest known satellite relative to the body it orbits. It was discovered in 1978. ¹

2. 02

   Always the same face

   Pluto and Charon always show each other the same face, a mutual tidal lock. That is why they are sometimes called a double dwarf planet. ¹

3. 03

   Pluto paints its pole

   Its reddish north pole, nicknamed Mordor Macula, comes from methane escaping Pluto: Charon traps it with its gravity and sunlight turns it into reddish substances called tholins. ²

4. 04

   A century of day, a century of night

   At its poles, a hundred years of continuous sunlight alternate with another century of darkness, at temperatures of −257 °C. ²