1.
A comet is a meteoroid that strikes Earth.
2.
A large, blue-green, gaseous planet similar to Uranus is Neptune.
3.
The inner planets are Pluto, Uranus, Neptune, Saturn and Jupiter.
4.
A large, gaseous planet with the lowest density and at least 47 moons is Saturn
5.
The inner 4 planets include Mars, Earth, Venus, and Mercury.
6.
The gas planet with the lowest density and hundreds of thin rings is ____________.
A. 
B. 
C. 
D. 
7.
Johannes Kepler discovered that the orbits of the planets are _____________.
A. 
B. 
C. 
D. 
8.
The second planet from the sun that is very hot and has sulfuric acid clouds is __________.
A. 
B. 
C. 
D. 
9.
One of the gas giants, _________, has an axis of rotation nearly parallel to the plane of its orbit.
A. 
B. 
C. 
D. 
10.
Two planets with similar mass and size are _______.
A. 
B. 
C. 
D. 
11.
The planet that averages 150 million km (93,000,000 miles) or one AU, from the Sun is _____.
A. 
B. 
C. 
D. 
12.
______________ is the largest moon in the solar system.
A. 
B. 
C. 
D. 
13.
The largest known volcano in the solar system is an extinct volcano known as Olympus Mons found on the planet ________.
A. 
B. 
C. 
D. 
14.
The planet closest planet to the Sun is __________.
A. 
B. 
C. 
D. 
15.
The planet that appears reddish-yellow due to iron oxide in its rocks is ____________.
A. 
B. 
C. 
D. 
16.
The largest of _____________ moons, Titan, is larger than the planet Mercury
A. 
B. 
C. 
D. 
17.
At times, the planet _________ is actually the farthest planet from the Sun.
A. 
B. 
C. 
D. 
18.
The Great Red Spot, a continuous storm, is located on the planet__________.
A. 
B. 
C. 
D. 
19.
Methane gives ___________ their blue-green color.
A. 
B. 
C. 
D. 
20.
The solid portion of a comet is called its _____________.
A. 
B. 
C. 
D. 
21.
A cloud of gases around the solid portion of a comet is known as the ____________.
A. 
B. 
C. 
D. 
22.
__________ are small pieces of rock moving through space.
A. 
B. 
C. 
D. 
23.
_________ published the Sun-centered model of the solar system in 1543.
A. 
B. 
C. 
D. 
24.
When small pieces of rock moving through space enter Earth's atmosphere and completely burn-up they are called __________.
A. 
B. 
C. 
D. 
25.
Pieces of rock that actually strike Earth's surface are called ____________.
A. 
B. 
C. 
D.