Name Date Class
LESSON 1
The Structure of the Solar System
Directions: On each line, write the term from the word bank that correctly replaces the underlined words in each
sentence. Use each term only once. NOTE: You may need to change a term to its plural form.
asteroidastronomical unitcometorbit
period of revolutionperiod of rotationstar
1.Many objects, including planets, travel around the Sun.
2.Orbiting objects made of gas, dust, and ice come from the
outer parts of the solar system.
3.The Sun is a(n) structure in space made of gases in which
nuclear fusion reactions occur.
4.In 365 days, Earth completes a(n) full journey around
the Sun.
5.In 24 hours Earth completes a(n) full turn, also called a
complete spin.
6.Millions of small, rocky objects orbit the Sun between the
orbits of Mars and Jupiter.
7.A(n) distance equal of about 150 million km is the average
distance from Earth to the Sun.
The Solar System9
Name Date Class
LESSON 1
The Structure of the Solar System
Earthinner planetsJupiterMars
MercuryNeptuneouter planetsSaturn
SunUranusVenus
Directions: Label this diagram by writing the correct term from the word bank on each line.
The Solar System13
Name Date Class
LESSON 1
The Structure of the Solar System
Directions: On each line, write the term from the word bank that correctly completes each sentence. Some terms
may be used more than once or not at all.
astronomicalclosercometellipticalenergy
fartherfasterfocifocusgas giants
gravitationalinnerouterplanetrevolve
rotateslowersolar systemstarsSun
The night sky offers a fascinating view into space. Most of the specks of light in
the night sky are (1.) . They exist far beyond our
(2.) . The largest object in our solar system is the
(3.) , which produces an enormous amount of
(4.) . The Sun also applies a(n) (5.)
pull on the planets. When you look into the night sky, you might see light reflected off a(n)
(6.) , such as Venus.
Objects in space (7.) around the Sun along a
stretched-out circle called a(n) (8.) orbit. Planets also
(9.) , or spin. There are four (10.)
planets that are made up mostly of solid rocky materials. These objects are spherical and
have a mass larger than the total mass of all other objects whose orbits are nearby. There
also are four (11.) planets made of gases, including helium and
hydrogen. These four planets are sometimes termed (12.) .
Distance in space is measured in (13.) units. A planet’s
speed changes as it orbits the Sun. A planet that is close to the Sun moves
(14.) than a planet that is far from the Sun. Also, planets that
are (15.) from the Sun have longer periods of revolution than
planets that are closer to the Sun. The shape of a planet’s orbit is determined by two
(16.) points. These (17.) are equal
distances from the center of the ellipse.
14The Solar System
Name Date Class
LESSON 1
The Structure of the Solar System
Key Concept How are the inner planets different from the outer planets?
Directions: On the line before each description, write the letter of the term that matches it correctly. Some terms
will be used more than once.
1.four planets closest to the Sun
2.nonspherical rocky objects
3.the largest object in the solar system
4.Jupiter, Saturn, Uranus, and Neptune
5.one trillion of them might orbit the Sun
6.a source of light energy
7.planets made of mostly solid rocky materials
8.Ceres, Pluto, Eris, and Makemake
9.planets made mainly of ice and gases
10.Mercury, Venus, Earth, and Mars
11.sometimes called gas giants
12.where nuclear fusion reactions occur
13.planets much larger than Earth
A.Sun
B.inner planets
C.asteroids
D.outer planets
E.dwarf planets
F.comets
16The Solar System
Name Date Class
LESSON 1
The Structure of the Solar System
Key Concept What is an astronomical unit, and why is it used?
The Astronomical Unit (AU)Planet / Average Distance (km) / Average Distance (AU)
Mercury / 57,910,000 / 0.39
Venus / 108,210,000 / 0.72
Earth / 149,600,000 / 1.00
Mars / 227,920,000 / 1.52
Jupiter / 778,570,000 / 5.20
Saturn / 1,433,530,000 / 9.58
Uranus / 2,872,460,000 / 19.20
Neptune / 4,495,060,000 / 30.05
Directions: Use the table to complete each statement.
1.Astronomical units are used for measuring in space because
.
2.The closest inner planet to the Sun is . In astronomical
units, this planet is from the Sun.
3.The closest outer planet to the Sun is . In astronomical
units, this planet is from the Sun.
4.In astronomical units, Earth is from the Sun.
5.An astronomical unit is given as the average distance from the Sun because orbits are
not perfect circles; they are .
6.Neptune is about times farther from the Sun than Jupiter,
and Jupiter is about times farther from the Sun than Earth.
18The Solar System
Name Date Class
LESSON 1
The Structure of the Solar System
Key Concept What is the shape of a planet’s orbit?
Directions: Circle the phrase that correctly completes the sentence.
1.Planets revolve around the Sun
2.An ellipse is like a
3.A planet moves slower
4.A planet’s speed increases
5.Planets that are farther from the Sun
6.The shape of a planet’s orbit
The Solar System19