Moons

Quizbowl

Luna

• Earth

• 5th largest satellite in the solar system

• The flat dark lunar plains are called maria (singular: mare) and are mainly concentrated on the near side of the moon.

• The most famous one is Mare Tranquillitatis, the Sea of Tranquility (where the Apollo 11 landed)

Phobos

• Mars

• Discovered by Asaph Hall III in 1877

• Orbits more closely to the planet than any other moon (3,700 miles)

• Appears to set twice in the east each day

• Stickney Crater

• Mariner IX became the first spacecraft to provide close-up photos of Phobos (1971)

Deimos

• Mars

• Discovered by Asaph Hall III in 1877

• 1/7th the mass of Phobos

• Only named craters are Swift and Voltaire

• Might have been an asteroid pushed out of Jupiter’s orbit

Io

• Jupiter

• Innermost of the four Galilean moons (the moons discovered by Galileo)

• 4th largest in the solar system

• Most geologically active with over 400 volcanos.

• Pioneer 10 first passed by in December 1973.

Ganymede

• Jupiter

• Largest moon, only one with its own magnetosphere

• First photographed close-up by Pioneer 10 in 1973.

• Largest dark plain is Galileo Regio

Titan

• Saturn

• Saturn’s largest, 2nd largest in the solar system

• Only known satellite with a dense atmosphere & evidence for stable surface liquid

• Discovered in 1655 by Christiaan Huygens

• Most likely place for microbial life outside of earth (nitrogen rich atmosphere, surface liquid)

• Highly reflective area Xanadu

Iapetus

• Saturn

• Saturn’s 3rd largest moon

• Distinctive two-tone coloration; part of it is red-brown, while part is bright gray.

• Discovered by Giovanni Cassini in 1671

• Charlemagne Crater & bright northern region Roncevaux Terra.

• Some of the highest peaks in the solar system

Titania and Oberon

• Uranus

• Discovered on the same day in 1787 by William Herschel, who also discovered Uranus itself in 1781

• 1986 Voyager 2 became the only spacecraft to date to visit the Uranian moons

• Extreme seasons- 1st moon has cycles of 42 years of sunlight, then 42 years of darkness.

• 1st moon’s largest crater is Gertrude Crater

• 2nd moon’s largest feature is the Mommur Chasma

Triton

• Neptune

• Only large moon with a retrograde (opposite of the planet) orbit

• 7th largest moon, thought to have been captured from the Kuiper Belt

• Geologically active and has geysers that are assumed to erupt nitrogen

• Voyager 2 visited in 1989 and is the only space probe to have done so

• Western hemisphere consists of an unexplained series of fissures and depressions sometimes called “cantaloupe terrain.”

Charon

• Pluto

• Wasn’t discovered until 1978

• Covered in water ice and may also have active cryo-geysers.

• Because the center of mass of the system lies outside of both Pluto and itself, it doesn’t truly orbit Pluto