What is special about how Pluto and Charon face each other?

They always show each other the same side

They spin in opposite directions

Charon Quiz: Pluto's Big Moon and Its Giant Canyons

This Charon quiz flies past Pluto with New Horizons to meet its largest moon. Play an interactive set of 10 questions on James Christy's 1978 discovery, Charon's size, mutual tidal locking, the double dwarf planet idea, the 2015 flyby, the red polar cap called Mordor Macula, huge canyons and the mythological ferryman.

Start Charon Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

Planet
Which world does Charon orbit?
Found
When was Charon discovered?
Size
How big is Charon compared with Pluto?
Lock
What is special about how Pluto and Charon face each other?
Center
Where is the balance point of their orbit?
Probe
Which spacecraft flew past Charon in 2015?
Red
What is Charon's reddish north polar region nicknamed?
Canyons
What did New Horizons reveal across Charon?
Myth
Who was Charon in Greek myth?
Name
Whose name also inspired the moon's name?

Explanations: answer key for all 10 questions

Q1: Which world does Charon orbit?
Answer: Pluto
It is Pluto's largest moon.
Q2: When was Charon discovered?
Answer: 1978
James Christy spotted it.
Q3: How big is Charon compared with Pluto?
Answer: About half Pluto's width
It is unusually large for a moon.
Q4: What is special about how Pluto and Charon face each other?
Answer: They always show each other the same side
They are mutually tidally locked.
Q5: Where is the balance point of their orbit?
Answer: In space between them
This is why some call them a double system.
Q6: Which spacecraft flew past Charon in 2015?
Answer: New Horizons
It sent sharp images home.
Q7: What is Charon's reddish north polar region nicknamed?
Answer: Mordor Macula
It may come from gas escaping Pluto.
Q8: What did New Horizons reveal across Charon?
Answer: Huge canyons and cliffs
Some are far longer than the Grand Canyon.
Q9: Who was Charon in Greek myth?
Answer: The ferryman of the dead
He carried souls across a river.
Q10: Whose name also inspired the moon's name?
Answer: Christy's wife Charlene
Christy liked the sound of it.

Charon Quiz – Pluto's Big Moon and Its Giant Canyons

Charon, discovered by James Christy in 1978, is Pluto's largest moon, about half Pluto's width. Pluto and Charon are mutually tidally locked, always showing each other the same face.

Their balance point lies in space between them, so some scientists call them a double dwarf planet. NASA's New Horizons spacecraft flew past in July 2015 and sent back detailed images.

Charon has a reddish north polar region nicknamed Mordor Macula and huge canyons far longer than the Grand Canyon. It is named after the ferryman of the dead in Greek myth, a nod also to Christy's wife Charlene.

What This Quiz Teaches

Space fans will enjoy these questions.

What Charon orbits
Who found it
How it moves with Pluto
What New Horizons saw
How it got its name

Did You Know?

Charon orbits Pluto about every six days.
Pluto has four other small moons.
Charon's surface is mostly water ice.
Some features are named after fictional explorers and vessels.
Its canyons may have formed as an inner ocean froze and expanded.