You learned in the first animation that gravity attracts objects and keeps the planets revolving around the sun.
Let’s review some other vocabulary terms that are essential to understanding in this lesson. After you’ve done this, answer the questions below.
Density A measurement of how compact an object is. If an object is heavy and small, it has a high density.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
Gas Giant Planets The planets in our solar system--Jupiter, Saturn, Uranus and Neptune--that have thick atmospheres and don't have solid outer layers.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
Gravity The force of attraction between masses.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
Mass The amount of material contained in an object, such as gas or dust.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
Planet A spherical object that orbits the sun and has a large amount of gravity.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
Solar Radiation The light and energy that come from the sun.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
Solar System A group of planets and other objects that revolve around a star. The star in our solar system is the sun.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
Terrestrial Planets The planets in the solar system--Mercury, Venus, Earth and Mars--that have solid rocky surfaces.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
Answer the following questions in the note box, below: