Page 196 - Science Course 3 (Book 2)

The Structure of Our Solar System Mo13-L1a: What are the Planets of Our
Solar System?
Lesson 1

astronomical unit

the average distance from earth to the Sun – about
150 million km.
In this topic, you will learn the following
lessons:
Mo.13–L1a: What are the Planets of Our Solar
System?

Mo13–L1a What are the Planets of Our Solar
System?

KEY CONCEPTS:
1. How are the inner planets different from the outer
planets?
2. What is an astronomical unit and why is it used?
3. What is the shape of a planet’s orbit?
period of revolution
is the time it takes an object to travel once around
Vocabulary A-Z the Sun.

Let us learn some vocabulary

asteroid

is one of the millions of small, rocky objects.

period of rotation
comet
is the time it takes an object to complete one
is made of gas, dust, and ice and moves around rotation.
the Sun in an oval-shaped orbit.

Axis of
rotation
(24 hours)

about 150 million km

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