| Mercury, Venus, Earth, and Mars are ____ (rocky) planets. |
1969 |
| Venus is the ____ planet from the Sun. |
asteroid |
| Mercury is the ____ planet from the Sun. |
charged |
| The Sun emits a stream of ____ particles called the solar wind. |
eighth |
| Neptune is the ____ planet from the Sun. |
first |
| Mars is the ____ planet from the Sun. |
fourth |
| Humans first walked on the Moon on July 21, ____. |
second |
| The ____ belt is located between the orbits of Mars and Jupiter. |
terrestrial |
