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   The "Gregorian Calendar" option lets you toggle between Julian
and Gregorian calendars.  The Julian calendar is usually used for
all dates before 1582,  and in some countries,  was used for many
years thereafter.  You will probably wish to use Gregorian dates
for all dates after 1918 and Julian dates for all those before
1582.  For those in between,  which calendar was in use varied by
country. Britain, and therefore its colonies,  used Julian dates
until 1752. Japan changed over in 1873.  Russia/the USSR changed
over in 1918.

   Clicking on "Current Time"  causes Guide to look at your computer's
clock and to use its date and time.  You can get the same effect at
any point in the program by hitting the F3 key,  or by clicking with
the right mouse button on the time shown in the legend area.

   Clicking on any of the twelve month keys resets the time to the same
date in that month.

   Outside the Time Box, hit Alt-0 to reset the time to midnight UT.

   If you want to reset the time by typing it in, use the "Enter Time"
feature in the Extras menu (page 52),  or left-click on the
time zone shown in the legend.

15:  PLANETARY ANIMATION AND EPHEMERIS CREATION       

   Using the Animation Menu you can watch planets, asteroids,
satellites, comets and stars move in time-lapse animation. This menu
may also be used to record the tracks left by an object over time or
to list ephemerides in a file.  For reasons that will become apparent,
animation,  ephemerides, and tracks are linked concepts in Guide.

   From the main menu,  use the Animation option. The Animation Menu
looks like this:

Animation Dialog
Add a Trail
Make Ephemeris
Make an .AVI

   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.

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