PLANETS OF THE SOLAR SYSTEM

The inner planets are mostly rock and metal.

1. Mercury2. Venus3. Earth4. Mars

The outer planets are mostly gas and dust.

5. Jupiter 6. Saturn7. Uranus8. Neptune

1

2

3

4

6

7

8

A planet is any body in orbit around the Sun that has enough gravity to form a sphere and that has cleared the neighborhood near its orbit of smaller objects.

5

The Sun

The planets that are made of gas and dust are much bigger than the planets that are made of rock and metal.

Earth

Jupiter

Uranus

Which of the following planets is mostly rock and metal?

Saturn

Uranus

Mars

Saturn is made of gas and dust. Do you think it would be bigger or smaller than Mars?

Bigger than Mars

Smaller than Mars

Match each planet name to the diagram.

2

3

4

6

7

8

5

Mercury

Saturn

Venus

NeptuneEarth

MarsUranus

Jupiter

1

What is Neptune mostly made out of?

Metal and Rock

Dust and Gas

Astronomers are planning to define a new type of planet. This new type is a “plutoid” or “dwarf

planet.” Plutoids are not big enough to clear their

path of other objects. Pluto is a plutoid. So are Ceres, Eris,

Makemake, and Haumea.

Pluto is in orbit around the sun, but it has a smaller object in its immediate neighborhood.

Is it a planet?

Yes

No

Yes, but it’s a dwarf planet