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 [email protected] camera
Right [email protected] the selected object
Mouse wheel,@
Middle [email protected] distance to selection
left [email protected] target, double click to center

Keyboard commands:


[email protected] the sun (Home)
[email protected] on selected object
[email protected] selected object
[email protected] selected object
[email protected] the selected object at a rate synced to its rotation
[email protected] motion

Free movement

[email protected] closer to object
[email protected] farther from object
[email protected]
[email protected] velocity to 1 km/s
[email protected] velocity to 1,000 km/s
[email protected] velocity to 1,000,000 km/s
[email protected] velocity to 1 AU/s
[email protected] velocity to 1 ly/s
[email protected] velocity by 10x
[email protected] velocity by 10x
[email protected] direction
[email protected] movement direction toward center of screen


[email protected] time
[email protected] 10x faster
[email protected] 10x slower
[email protected] time


[email protected] galaxy rendering
[email protected] planet and moon labels
[email protected] planet orbits
[email protected] HUD Text
[email protected] planet atmospheres (cloud textures)
[email protected] wireframe mode
/@Toggle constellation diagrams
= @Toggle constellation labels
;@Toggle earth-based equatorial coordinate sphere
[email protected] star labels
[email protected] 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
[email protected] field of view


[email protected] 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 directly.


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


Force the use of indirect OpenGL rendering contexts.


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.


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


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