Exam 23: Planets and Their Moons

Spacecraft have photographed volcanic eruptions on __________, one of Jupiter's moons.

The Moon's __________ are flat expanses of volcanic rock.

Jupiter, Saturn, Uranus, and Neptune are called the __________ planets.

Europa is very similar to Earth in that its interior is composed of rock, and much of its surface is covered by water. However, Europa's surface is covered with __________.

The craters on Mercury are about __________ years old.

The surface of Jupiter consists mainly of:

__________ is the outermost of the four moons of Jupiter detected by Galileo.

Titan is the largest moon of __________.

Io is the most active volcanic body in the Solar System.

Asteroids may change their orbits frequently and erratically.

Io has a smooth, nearly crater-free surface because:

Jupiter, Saturn, Uranus, and Neptune have retained large amounts of hydrogen and helium and are called the __________ __________.

The Moon formed __________.

The atmosphere of Venus is 90 times denser than the Earth's atmosphere.

Mercury, Venus, Earth, and Mars are called the __________ planets.

A __________ is composed of ice mixed with bits of silicate rock, metals, and frozen crystals of methane, ammonia, carbon dioxide, and other compounds.

Uranus and Neptune are enveloped in atmospheres composed primarily of __________ and __________.

Io is a moon of __________.

__________ was reclassified as a dwarf planet in 2006.

A glowing object that appears in the sky, traveling slowly around the Sun in an elongated orbit, is called a/an ____________________.