| A | B |
|---|
| terrestrial | earth |
| greenhouse effect | The trapping of heat by the atmosphere |
| gas giants | The first four outer planets that are massiveand do not contain solid surfaces. |
| ring | a thin disk of ice and rock that surrounds the gas giants. |
| Jupiter | Io, Europa, Ganymede, and Callisto surround this planet. |
| Ganymede | The largest moon in the solar system. |
| Mars | Where probes have successfully explored. |
| Saturn | has the most spectacular rings of any planet. |
| Neptune | a cold blue planet. |
| Pluto | smaller than Earth's moon. |
| Mercury | closest planet to the Sun. |
| Venus | has the strongest greenhouse effect. |
| Earth | The living planet |
| Uranus | axis is tilted 90 degrees from vertical |
| moon phase | The different shapes of the moon we see from the Earth. |
| Eclipse | When the Moon's shadow hits the Earth or the Earth's shadow hits the moon. |
| Umbra | The very darkest part of the Moon's or Earth's shadow in a solar or lunar eclipse. |
| Penumbra | The larger part of the Moon's or Earth's shadow in a solar or lunar eclipse. |
