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Animation Dialog Add a Trail Make Ephemeris Make a Movie By default, the "Add a Trail" and "Make Ephemeris" options are grayed out, until you have specified a moving object (one within the solar system) by right-clicking on it. To use animation, turn on the Animation Dialog, and zoom and pan the chart area to show the solar system object(s) you want to see animated. Set the animation rate in the dialog to the desired value. You may set step sizes from one second to over a hundred years, either directly (by clicking on the button showing the animation rate in the dialog) or by using the "Faster" and "Slower" buttons in the dialog. Once you have set the desired rate, you can click on the double-arrow "animate forward" button in the Animation Dialogue, and solar system objects will start to move. You can then click on the central "stop animation" box when done. The remaining arrows allow you to run the process backward, or to take single steps in time forward or backward. For your first few efforts, you will probably do well to start with a small step size and work your way up. You can also run animation in "real time" (the objects move according to the actual time, as provided by the computer's built in clock) by clicking on Real Time. When you do this, Guide will ask you how often the display should be updated. (If you're following a rapidly moving artificial satellite, it may be necessary to update its position once a second when in Real Time mode. But when following a slower-moving asteroid or planet, an update rate of once a minute or even less may work nicely.) Clicking on "Real Time" again returns you to your previous rate of animation. The animation dialog contains three extra, very important buttons in the "Locked On" box: ( ) Moving Object ( ) Horizon (*) Stars In the default, "Stars" mode, the animation stays fixed relative to the stars. You may still see stars move due to proper motion, if the animation step size is large enough, but they stay basically fixed. Instead, the animation can keep a moving object centered, or can stay fixed at a given point relative to the horizon. For a good example of the usefulness of the "Moving" option, zoom in on Jupiter at about level 12, and set the animation rate to about 15 minutes.
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