The Craters on Mercury Are About __________ Years Old

Q40: Some meteorites contain small, round grains about

Q41: Spacecraft have photographed volcanic eruptions on _,

Q42: The Moon's _ are flat expanses of

Q43: Jupiter, Saturn, Uranus, and Neptune are called

Q44: Europa is very similar to Earth in

Q46: The surface of Jupiter consists mainly of:<br>A)

Q47: _ is the outermost of the four

Q48: Titan is the largest moon of _.<br>A)

Q49: Io is the most active volcanic body

Q50: Asteroids may change their orbits frequently and