30 Spectacular Facts about Charon

By Karin Lehnardt, Senior Writer

Published September 7, 2017Updated September 5, 2019

The entire Pluto system has four small satellites (Nix, Hydra, Kerberos, and Styx) that orbit a “binary planet” that is composed of Pluto and its largest moon, Charon._[7]
Unlike Pluto’s moons of Hydra and Nix, Charon is not oblong shaped. Rather, it was big enough to have collapsed into a spheroid shape due to its own gravity._[7]
Because Charon orbits Pluto in the same time it takes Pluto to make one rotation (6½ Earth days), Charon hangs permanently in one place in Pluto’s sky, never rising or setting. This is called “tidal locking.”_[3]
Charon was initially named S/1978 P 1, which indicates the year it was discovered and the fact it was the first object observed around Pluto (hence, “P 1”)._[7]
Charon is larger in comparison to its world than any other moon in the solar system. Earth’s moon is the next largest in comparison to its planet._[5]

James Christy (left) discovered Charon after he noticed a very slight bulge on one side of Pluto

Pluto was discovered in 1930 by American astronomer Clyde Tombaugh. Its moon, Charon, wasn’t discovered until 1978, by U.S. Naval Observatory scientist James W. Christy._[2]
Charon is usually pronounced as “SHAR-on” although “CARE-on,” which is the Greek pronunciation, is also considered correct. The astronomer who discovered the moon suggested its name because it was a version of his wife Charlene’s nickname “Char.”_[7]
Charon actually does not orbit Pluto; rather, Pluto and Charon orbit a common center of gravity, called a barycenter, located just above Pluto’s surface. Because of this, and because of its large size, astronomers debate whether Charon should be considered a dwarf planet in its own right._[3]
A 100 lb. person on Earth would weigh just under 3 pounds on Charon. A 100 lb. person on Charon would weigh just over 3, 503 pounds on Earth._[11]
Charon has a complex system of fractures and chasms that are four times as long as the Grand Canyon and twice as deep in some places. Astronomers note that it looks like the entire crust of Charon has been split open._[3]

The moon expanded in its past, and--like Bruce Banner tearing his shirt as he becomes the Incredible Hulk --Charon’s surface fractured as it stretched.

- NASA researchers

Charon appears to be covered in frozen water, differing from Pluto’s surface, which is composed of frozen nitrogen, methane, and carbon dioxide._[1]
Astronomers believe that Charon has active cryogeysers (ice geysers) and cryovolcanoes (ice volcanoes), which suggest that Charon has an ice-based geology._[10]
Some astronomers hypothesize that Charon was formed around 4.5 billion years ago by a collision between Pluto and a Kuiper object, much like how the Earth and its moon were formed. Other astronomers believe that Pluto and Charon collided with each other before starting to orbit each other._[7]
Charon is named after the Greek mythological figure Charon the ferryman, who rows souls across the River Styx to Pluto’s realm in the underworld. His name literally means “fierce brightness.”_[2]

Charon is the brother of Thanatos (death) and Hypnos (sleep)

Astronomers initially expected the surface of Charon to be monotonous and riddled with crater marks. After viewing footage from the New Horizon’s probe, they found that it is covered with mountains, canyons, landslides, color variations, and more._[5]
A unique feature of Charon that has baffled astronomers is called “Mountain in a Moat,” which is a large mountain rising out of a depression._[1]
Charon’s northern region is darker than the rest of moon. The New Horizon’s team named this area “Mordor,” a region in The Lord of Rings. The discoloration might be from small particles of tar that drifted from the top of Pluto’s atmosphere._[8]
In the Mass Effect video game, Charon is not a moon but a chunk of ice that holds an ancient civilization’s technology that allows for faster-than-light travel._[6]
The New Horizons spacecraft flew within 17,000 miles of Charon on July 14, 2015, and it is the only probe to have studied the moon. Launched on January 19, 2006, the craft arrived at the Pluto-Charon system after a 9-year journey._[3]

The New Horizons spacecraft is the only spacecraft to visit the Pluto system

One of the most impressive chasm on Charon is named Serenity Chasm, after the beloved ship on Joss Whedon’s cult classic show, Firefly. This chasm is 37 miles wide._[8]
The distance between Pluto and its moon, Charon, is 12,200 miles (19,640 kilometers). The difference between Earth and its moon is on average 239,000 miles (385,000 km)._[7]
Charon’s northern hemisphere has more crater marks than the south, which suggests the northern terrain is older. The south seems to have been subjected to some kind of resurfacing process that erased or buried older craters. Scientists are unsure what causes the resurfacing process._[1]
Pluto is about half the width of the United States. Charon is just over half the size of Pluto, which would make it slightly larger than India._[7]
It takes light 4.6 hours to travel from Earth to Charon._[9]
It would take about 6,293 years to drive to Pluto’s largest moon, Charon, from Earth going a steady 65 mph. It would take a Boeing 777 going 590 mph about 680 years to go from Earth to Pluto. It took the New Horizons probe going 50,000 mph, the fastest speed ever for a launched spacecraft, a little under a decade to get to Charon._[4]

"Vader Crater" is named after the iconic tragic hero/villian in the Star Wars franchise

The New Horizon’s spacecraft team has named some Charon craters after several beloved characters from both Star Trek and Star Wars, including Vader Crater. James T. Kirk, Spock, and Uhura also get their own craters._[8]
The astrological symbol for Charon is a linked capital C and a capital H. The astrological symbol is a floating circle above a crescent, which reflects Charon’s mythical meaning as a boatman across the River Styx._[2]
While not confirmed, astronomers believe Charon does not have an atmosphere or a surrounding collection of gases._[1]
Both Pluto and Charon orbit the sun once every 248 years._[1]
The temperature on Charon is frigid, at -364° Fahrenheit (-220° Celsius). Neptune’s moon, Triton, is the coldest measured object in our solar system, with an average temperature of -391° F._[5]