Page 197 - Science Course 3 (Book 2)

Mo13-L1a: What are the Planets of Our Solar System?

Let’s Begin

What is the Solar System?

Almost all of the specks of light you can see in the
night sky are stars.

(Mercury) (Venus)

A few of the tiny lights are part of our solar system.
(Earth) (Mars)
Stars are much farther away than objects in our solar
system. Jupiter, Saturn, Uranus, and Neptune are the outer
planets.
Objects in the Solar System
The outer planets are mostly ice and gases, such as
hydrogen and helium.
The largest object in the solar system is the Sun, a
star.

Planets orbit the Sun and have nearly spherical
shapes.

(Jupiter) (Saturn)

The mass of a planet must be much larger than (Neptune) (Uranus)
the total mass of all other objects whose orbits
are close by.
Key Concept

Eight of the objects in the solar system are planets. What are the Planets of Our Solar System?

• Mercury • Jupiter Describe how the inner planets differ from the
• Venus • Saturn outer planets.
• Earth • Uranus
• Mars • Neptune

Mercury, Venus, Earth, and Mars are the inner planets.

The inner planets are mostly solid, rocky material.
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