Download Our Solar System

Name ______________________________________ Date _________
TEKS Review
3.8D
TEKS 3.8D identify the planets in Earth’s solar system and their position in relation to the Sun
Our Solar System
The Planets
Inner Planets vs. Outer Planets
A solar system is made up of a star and
everything that revolves around it. Our solar
system consists of the sun, eight planets, many
moons, many dwarf planets, an asteroid belt,
comets, meteors, and other celestial objects.
The sun is the center of our solar system. It is
by far the largest object in the solar system.
The sun makes up more than 99% of the solar
system’s mass! All other objects that are in the
solar system orbit the sun.
The inner planets—Mercury, Venus,
Earth, and Mars—are relatively small. They
are also made of rock and have few or no
moons. The outer planets—Jupiter, Saturn,
Uranus, and Neptune—are huge, mostly
gaseous, and have rings. The outer planets
also have many moons. In general, the farther
a planet is from the sun, the colder it is.
Between Mars and Jupiter is the asteroid
belt, a ring-shaped area where there are many
asteroids. Asteroids are small bodies in space
made of rock or metal. There are other areas
of asteroids, too, but this is the main belt.
Some of the particles are left over from the
formation of the solar system. Other bodies
have been added as they break off planets or
enter our solar system.
A planet is a large, spherical body that
revolves around a star. The planets, in order
from the sun, are Mercury, Venus, Earth,
Mars, Jupiter, Saturn, Uranus, and Neptune.
All of the planets as well as most other
celestial bodies orbit the sun in roughly
circular orbits that lie in the same plane, which
is known as the ecliptic.
The Solar System
Mercury
Earth
Venus
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
Jupiter
Saturn
Uranus
Neptune
This diagram is not to scale. Also, the planets
do not line up in a straight line. They are all at
different points in their orbits around the sun.
Mars
TEKS 3.8D
Page 1 of 6
Name ______________________________________ Date _________
TEKS Review
3.8D
You may know that Pluto was once
considered to be the ninth planet in our solar
system. It is not very large, and there are other
objects in its orbit. Astronomers found other
objects similar to Pluto and think there may be
many more. Scientists had a decision to
make—either classify many other objects as
planets or modify the definition of a planet.
Scientists chose to classify Pluto as a dwarf
planet in 2009. Eris, Ceres, Haumea, and
Makemake are four other dwarf planets in our
solar system.
the largest volcano in the solar system, and it
has dust storms that can last for months.
Features of the Planets
Saturn is best known for its rings, made
of ice, dust, boulders, and frozen gas. The
rings stretch about 136,200 km (84,650 mi)
from the center of the planet! Like Jupiter,
Saturn has dozens of moons.
Mercury, which is closest to the sun, is
about the size of Earth’s moon. Like the
moon, Mercury has almost no atmosphere
and a surface covered with craters and dust.
The side of Mercury facing the sun is hot—
about 430°C (810°F)! The side not facing the
sun can become very cold, however—about
–180°C (–290°F).
Venus is the brightest object in the night
sky, after the moon. This planet is about the
same size as Earth, and it is rocky. The
similarities end there. Venus can become very
hot, reaching about 460°C (860°F). It is even
hotter than Mercury because Venus’s thick
atmosphere keeps heat from escaping.
Earth, the third planet from the sun, is
our home. Earth is the only planet on which
life is known to exist. About three-fourths of
the surface of our planet is covered with
oceans of liquid water. This makes Earth
unique among the planets and gives our planet
the nickname the blue planet.
Beyond the asteroid belt are the outer
planets. These are also called gas giants
because they are composed mainly of
hydrogen and helium.
Jupiter is the largest planet in the solar
system. It has rings and dozens of moons.
There is a huge storm on Jupiter that has
lasted for more than 400 years. The storm, like
a hurricane, has a name—the Great Red Spot.
Uranus also has many moons and rings.
This planet rotates on an axis that is tilted
much more than those of the other planets.
Uranus looks like a top that has fallen over but
is still spinning.
Neptune has many rings and moons and
the fastest winds in the solar system. The
winds can reach 2,000 km/hr (1,200 mi/hr)!
Number of Known Moons
Mercury
0
Jupiter
63
Venus
0
Saturn
62
Earth
1
Uranus
27
Mars
2
Neptune
13
Mars is called the red planet because of
its reddish soil. Its atmosphere is mostly
carbon dioxide. Scientists have evidence that
liquid water once existed on Mars. Mars has
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
TEKS 3.8D
Jupiter has a very
faint ring. The
diameter of Jupiter
is more than 11
times larger than
the diameter of
Earth!
Page 2 of 6
Name ______________________________________ Date _________
TEKS Review
3.8D
Hands-On Activity
A Scale Model of the Solar System
Materials
Most images of the solar system are not to scale. The sun is so large
and the planets are so far apart that it is not easy to show all the elements
of the solar system to scale. In this activity, you will make a scale model
of the solar system.
• 4-m length of string
• tape measure
• 8 markers of
different colors
Procedure:
1. At one end of the string, make a knot. This will represent the position of the sun.
2. One AU (astronomical unit) is equal to the distance between Earth and the sun.
In your model, 10 cm will represent 1 AU. Use the tape measure to find Earth’s
position in the model. Use a marker to mark this point on the string. Place a small
dot next to the planet’s name in the table to record which color you used.
3. Complete the Scale Distance column of the table. Repeat Step 2 for each planet,
using a different color marker for each.
Planet Data
Planet
Mercury
Average Distance
from the Sun (km)
Average Distance
from the Sun (AU)
Scale Distance Planet’s Diameter
(cm)
(km)
58 million
4/10
4
4,879
Venus
108 million
7/10
7
12,104
Earth
150 million
1
12,756
Mars
228 million
1 5/10
6,792
Jupiter
779 million
5 2/10
139,822
Saturn
1,433 million
9 6/10
120,536
Uranus
2,877 million
19 2/10
51,118
Neptune
4,503 million
30 1/10
49,528
Discussion Questions:
1. How would you describe the positions of the planets?
2. How could you add to your model to make it more accurate?
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
TEKS 3.8D
Page 3 of 6
Name ______________________________________ Date _________
TEKS Review
3.8D
Our Solar System
Label the solar system diagram.
In what ways is the solar system drawing above not to scale?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
What other objects are part of our solar system?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
TEKS 3.8D
Page 4 of 6
Name ______________________________________ Date _________
TEKS Review
3.8D
TEKS Assessment 3.8D
Fill in the letter of the best choice.
Look at the drawing below.
Look at the image below.
Which of the following is not true?
Which planet is the arrow pointing to?
Neptune
Jupiter
Saturn
Earth
This planet has more moons than
Earth.
This swirl you can see is a giant
storm called the Great Red Spot.
This planet is many times larger
than Earth.
This planet’s surface is much like
Earth’s surface.
Which planet has the shortest path
around the sun?
Earth
Venus
Mercury
Neptune
Which of the following planets is closest
in size to Jupiter?
Why is Pluto no longer considered to be
a planet?
Saturn
Mercury
It does not orbit the sun.
Mars
Earth
It has too many moons.
It is not large enough to have
cleared its orbit of debris.
It is too large to be classified with
the inner and outer planets.
Which planet is farthest from the sun?
Saturn
Neptune
Uranus
Jupiter
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
TEKS 3.8D
Page 5 of 6
Name ______________________________________ Date _________
TEKS Review
3.8D
Answer Key
Hands-On Activity (p. 3)
1. Answers will vary but should be based on the models. Sample answer: The four inner
planets are close to the sun and relatively close to one another. The four outer planets are
spaced farther apart and are much farther from the sun.
2. Check students’ answers. Sample answer: I could make the size of the planets to scale.
Student Response Activity (p. 4)
1. Check students’ answers. Beginning with the closest to the sun, students should label
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
2. Neither the distances of the planets from the sun or the relative sizes of the planets are to
scale.
3. Dwarf planets, asteroids, comets, dust, gases, and the moons of the planets are also part of
the solar system.
TEKS Assessment (p. 5)
1. D
2. B
3. A
4. C
5. D
6. C
TEKS Review and Assessment
© Houghton Mifflin Harcourt Publishing Company
TEKS 3.8D
Page 6 of 6