The dark region on the north pole of Pluto’s moon, Charon, is called Mordor.

The dark region on the north pole of Pluto’s moon, Charon, is called Mordor.

Mordor Macula /ˈmɔːrdɔːr ˈmækjʊlə/ is the informal name for a large red area about 475 km in diameter near the north pole of Charon, Pluto's largest moon. It is named after the black land called Mordor in J.R.R. Tolkien's The Lord of the Rings trilogy.

Charon (/ˈkɛərən/ or /ˈʃærən/), also known as (134340) Pluto I, is the largest of the five known natural satellites of the dwarf planet Pluto. It has a mean radius of 606 km (377 mi).

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Charon (moon)

Charon has a frigid surface, covered with methane and nitrogen ice, and possibly some water ice. Although Charon is mostly ice by mass, it may contain a small rocky core.

While Pluto is able to hold onto a tenuous atmosphere, Charon is not large enough. The moon is extremely cold, with polar temperatures ranging from minus 433 to minus 351 degrees Fahrenheit (minus 258 to minus 23 degrees Celsius).