1. Planets of the Solar System

2. 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.
The inner planets are mostly rock and metal.
Mercury
Venus
Earth
Mars 8 5 3 1 7
The outer planets are mostly gas and dust.
Jupiter
Saturn
Uranus
Neptune 4
The Sun 2 6

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

4. Which of the following planets is mostly rock and metal?
Saturn
Uranus
Mars

5. Bigger than Mars Smaller than 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

6. Match each planet name to the diagram.
Saturn
Neptune
Mercury
Earth 8 5 3 1 7 4 2 6
Venus
Jupiter
Mars
Uranus

7. What is Neptune mostly made out of?
Metal and Rock
Dust and Gas

8. 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.

9. Yes, but it’s a dwarf planet
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