Circle the best answer for each question.

1		With his telescope, Galileo discovered
			A)	the lunar maria
			B)	four moons of Jupiter
			C)	Neptune
			D)	the asteroids
2		Compared to the orbits of the planets, the orbits of comets about the sun are
			A)	perfect circles
			B)	longer and narrower
			C)	shorter and wider
			D)	exactly the same as those of the planets
3		Meteorites
			A)	are impossible to distinguish from terrestrial rocks
			B)	are composed chiefly of ice and dust
			C)	are the flashes of light that meteoroids produce when they enter the earth's atmosphere
			D)	reach the earth's surface without burning up
4		Mercury and Venus are similar in that they
			A)	rotate clockwise about their axes
			B)	possess thick atmospheres
			C)	lack moons
			D)	give off over twice as much energy as they receive from the sun
5		The first object of human origin to leave the solar system permanently is the
			A)	Pioneer 10 spacecraft
			B)	Mariner 10 spacecraft
			C)	Viking spacecraft
			D)	Galileo spacecraft
6		The orbits of all planets lie nearly in the same plane except for that of
			A)	Venus
			B)	Uranus
			C)	Mars
			D)	Pluto
7		Which one of the following statements about the inner planets is incorrect?
			A)	The inner planets are relatively small.
			B)	They are composed largely of rocky material.
			C)	They rotate fairly rapidly on their axes.
			D)	They possess low escape speeds.
8		Spacecraft that have landed on Venus found
			A)	extensive seas
			B)	an atmosphere rich in oxygen
			C)	surface temperatures hot enough to melt lead
			D)	thick clouds composed mainly of water
9		The seasons on Mars
			A)	last little over 24 hours
			B)	last nearly 2 years
			C)	are 6 months long
			D)	are about the same lengths as the earth's seasons
10		Life on Mars, if it exists, would have to adapt to all the following conditions except
			A)	intense solar ultraviolet radiation
			B)	an atmosphere rich in oxygen
			C)	an environment low in liquid water
			D)	a low average surface temperature
11		Ceres is
			A)	an asteroid
			B)	one of Mars's moons
			C)	Pluto's moon
			D)	the largest satellite of the solar system
12		Jupiter's moon Europa
			A)	has active volcanism
			B)	is Jupiter's largest moon
			C)	has a faint ring
			D)	appears to have an ocean of liquid water beneath an ice surface
13		The rings of Saturn
			A)	are split into thousands of narrow ringlets
			B)	consist of very large captured asteroids
			C)	are composed mainly of gaseous hydrogen and helium
			D)	are composed of metallic hydrogen
14		An annular eclipse of the sun occurs when the
			A)	earth is between the moon and the sun
			B)	earth is farthest from the sun
			C)	moon passes above or below the direct line from the sun to the earth
			D)	moon is farthest from the earth
15		Examination of lunar rocks indicates that all igneous activity on the moon stopped about
			A)	20 million years ago
			B)	1.5 billion years ago
			C)	3 billion years ago
			D)	4.6 billion years ago