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       celestia - A real-time visual space simulation


       celestia [options]


       This  manual  page  documents  briefly  celestia, a 3D space simulator.
       Celestia is a real-time visual simulation of space in our local  region
       of the universe. Choose a point within about 1000 light years of Earth,
       and Celestia will show you an approximation of how it would  appear  to
       your  eyes  were  you  actually  there.  Some of what Celestia shows is
       necessarily hypothetical--the farther away from Earth you get, the less
       real  data  there is and the more guesswork is involved.  Thus Celestia
       supplements observational data with good guesses  based  on  models  of
       stellar and planetary processes.

       Celestia  is  unique  in  its  ability  to  allow you to navigate at an
       immense range of scales.  Orbit a couple kilometers above  the  surface
       of  a  tiny, irregular asteroid, then head off toward Jupiter, watching
       it grow from a bright point of light into a looming sphere filling your
       field  of  vision.  Leave our solar system entirely and observe the sun
       as it fades from a brilliant disk to a bright star, disappearing almost
       entirely  as  you head off toward the Upsilon Andromeda system to orbit
       around its innermost giant planet.


       Celestia will start up in a window, display a welcome message and  some
       information  about  your  target (top left corner), your speed, and the
       current time (Universal Time, so it'll probably be a few hours off from
       your  computer's  clock.)  In Celestia, you'll generally have an object
       selected; currently, it's Eros, but it could also be  a  star,  planet,
       spacecraft,  or  galaxy.   The  simplest  way to select an object is to
       click on it.  Try clicking on a star to  select  it.   Right  drag  the
       mouse  to  orbit  arround the selected target.  Left dragging the mouse
       changes your orientation too, but the camera rotates about  its  center
       instead  of  rotating  around the target.  Rolling the mouse wheel will
       change your distance to the space station--you  can  move  light  years
       away, then roll the wheel in the opposite direction to get back to your
       starting location.  If your mouse lacks a wheel, you can use  the  Home
       and End keys instead.

       Press G and you'll zoom through space toward the selected star.  If you
       press G again, you'll approach the star even closer.  Press H to select
       our  Sun,  and  then  G  to  go  back to our solar system.  You'll find
       yourself half a light year away from the Sun, which looks merely like a
       bright  star  at  this  range.   Press G three more times to get within
       about 30 AU of the Sun and you will be to  see  a  few  planets  become
       visible near the Sun.


       Mouse functions:

       Left drag      orient camera
       Right drag     orbit the selected object
       Mouse wheel,
       Middle drag    adjust distance to selection
       left click     select target, double click to center

       Keyboard commands:


       H     Select the sun (Home)
       C     Center on selected object
       G     Goto selected object
       F     Follow selected object
       Y     Orbit the selected object at a rate synced to its rotation
       ESC   Cancel motion

       Free movement

       HOME   Move closer to object
       END    Move farther from object
       F1     Stop
       F2     Set velocity to 1 km/s
       F3     Set velocity to 1,000 km/s
       F4     Set velocity to 1,000,000 km/s
       F5     Set velocity to 1 AU/s
       F6     Set velocity to 1 ly/s
       A      Increase velocity by 10x
       Z      Decrease velocity by 10x
       Q      Reverse direction
       X      Set movement direction toward center of screen


       Space   stop time
       L       Time 10x faster
       K       Time 10x slower
       J       Reverse time


       U    Toggle galaxy rendering
       N    Toggle planet and moon labels
       O    Toggle planet orbits
       V    Toggle HUD Text
       I    Toggle planet atmospheres (cloud textures)
       W    Toggle wireframe mode
       /    Toggle constellation diagrams
       =    Toggle constellation labels
       ;    Toggle earth-based equatorial coordinate sphere
       B    Toggle star labels
       P    Toggle per-pixel lighting (if supported)
       [    Decrease limiting magnitude (fewer stars visible)
       ]    Increase limiting magnitude (more stars visible)
       {    Decrease ambient illumination
       }    Increase ambient illumination
       ,    Narrow field of view
       .    Widen field of view


       D   Run demo
       `   Show frames rendered per second

       It's possible to choose a star or planet by name:  press Enter and type
       in the name, and pressing Enter again.  You can use  common  names,  or
       Bayer  designations  and  HD  catalog  numbers  for  stars.   Bayer and
       Flamsteed designations need to be entered like "Upsilon  And"  and  "51
       Peg".   The  constellation must be given as a three letter abbreviation
       and the full Greek letter name spelled out.  HD catalog numbers must be
       entered with a space between HD and the number.


       The  glut  based  version  accepts  the  usual X Window System specific
       options, namely:

       -display DISPLAY
               Specify the X server to connect to. If not specified, the value
               of the DISPLAY environment variable is used.

       -geometry WxH+X+Y
               Determines  where window's should be created on the screen. The
               parameter following -geometry should be formatted as a standard
               X  geometry  specification.  The effect of using this option is
               to change the GLUT initial size and initial position  the  same
               as  if glutInitWindowSize or glutInitWindowPosition were called

       -iconic Requests all top-level windows be created in an iconic state.

               Force the use of indirect OpenGL rendering contexts.

       -direct Force the use of direct OpenGL rendering contexts (not all  GLX
               implementations  support  direct  rendering  contexts). A fatal
               error is generated if direct rendering is not supported by  the
               OpenGL implementation.

               If  neither -indirect or -direct are used to force a particular
               behavior, GLUT will attempt to use direct rendering if possible
               and otherwise fallback to indirect rendering.

               After  processing  callbacks  and/or events, check if there are
               any OpenGL errors  by  calling  glGetError.   If  an  error  is
               reported, print out a warning by looking up the error code with
               gluErrorString.  Using this  option  is  helpful  in  detecting
               OpenGL run-time errors.

       -sync   Enable  synchronous X protocol transactions.  This option makes
               it easier to track down potential   X protocol errors.


       Celestia has been written by  Chris  Laurel  <>
       and  it's  available  under the terms and conditions of the GNU General
       Public LIcense from

                                 May 23, 2001                      CELESTIA(1)