# Table of contents

Getting Started
Celestia Controls
Introduction
Mouse Controls
Keyboard Controls
- Navigation
- Via Arrow Keys
- Via number Pad
- Motion (Spaceflight)
- Time Control
- Labels to display
- What items to render
- Render/Display options
- Multiview options
- Other functions
Joystick Controls
Mac specific controls
Linux specific controls
Celestia FAQ
Graphics
Installing drivers
Crashes
Features
General questions
Windows questions
Celestia resources
License
Contributions
Acknowledgements

# Getting Started: Celestia

A real-time space simulation that lets you experience our universe in three dimensions.
Copyright © 2001-2023, Celestia Development Team
Celestia web site: https://celestiaproject.space/
Celestia documentation: https://celestiaproject.space/guides.html
Celestia WikiBook: https://en.wikibooks.org/wiki/Celestia
Celestia forums: https://celestiaproject.space/forum/
Celestia mobile: https://celestia.mobi/
Celestia GitHub repository: https://github.com/CelestiaProject/Celestia
Celestia content repository: https://github.com/CelestiaProject/CelestiaContent

## Getting Started Topics

1. Installing Celestia
   Celestia comes in a number of pre-built packages for multiple operating systems. Due to the large file size, many Celestia distributions have split this into two sections. One section is the Celestia program. The second section is content files with planet maps, stellar names/positions and some simple spacecraft. See Additional Celestia Content.
   NOTE: Celestia has a number of helper applications - including SPICE support, audio support, video recording support and Lua scripting support. Pre-built packages have options selected when they were prepared. You may desire different options, and compiling from source gives you more flexibility to make a custom version of Celestia. The Celestia sources are found at the Celestia GitHub repository. Instructions on compiling the source code is found in the Install file with the code.
   - Windows
     - Release version 1.6.x is available in the native Windows User Interface. For Win64(x64) it can be found at the Celestia web site in the downloads section. It is also available from the Microsoft store. Other sites contain pre-built versions with special options, including a Win32(x86) version. Check the Celestia forums for additional links and downloads. After downloading the installation executable, run the .exe file to install Celestia. Celestia 1.6.x will work when installed in any version of Windows from Vista and later; however, more recent releases of Celestia are geared to and tested on recent releases of Windows. If you are running an older version of Windows, you may need to run a previous version of Celestia. Be aware that Windows is protective of software installed in the Program Files directory tree. You will have far fewer problems modifying Celestia if you install it somewhere else, for example creating the folder "C:\MyPrograms" and installing Celestia there. The installation program will let you browse to wherever you want to install Celestia.
     - Developmental version 1.7.x is available in both native Windows user interface and Qt 6 user interface. The compiled files are found on the Celestia GitHub repository through GitHub actions and require a GitHub account (free) to download. From the Celestia GitHub page, click on the Actions link at the top. You will be presented with a list of recent workflows. Click on the link to the workflow from the latest update (near the top of the list). Under Artifacts there are two sets of files beginning with "celestia-windows-x64" (64-bit) or "celestia-windows-x86" (32-bit). Both user interfaces for that version of Windows are available as separate files. First create a folder for programs, for example "C:\MyPrograms". In this folder create a new folder named "Celestia".
     - For the native Windows user interface, download the wingui file. Extract the contents of the file into your Celestia folder. The Celestia program can be started by clicking on the celestia-win.exe file in the Celestia folder. You can create links or menu items to this file for easier starting. Note: Be sure your active directory is the Celestia folder when starting Celestia - or configuration files, data files, textures and models will not be found.
     - For the Qt Windows user interface, download the qt6gui file. Extract the contents of the file into your Celestia folder. The Celestia program can be started by clicking on the celestia-qt6.exe file in the Celestia folder. You can create links or menu items to this file for easier starting. Note: Be sure your active directory is the Celestia folder when starting Celestia - or configuration files, data files, textures and models will not be found.
     This will complete the installation of the Celestia program section. The developmental version does not come with the data files needed to run Celestia. See Additional Celestia Content for information to download and install these necessary files.
   - Linux and Unix
     - Release version 1.6.x can be found in four user interface styles. GTK is a full windowed graphical user interface with a menu and dialogs. Gnome is a full GTK interface that has been integrated into the Gnome desktop. KDE is a full windowed graphical user interface with menus, toolbars and integration into the KDE3 desktop. GLUT is a bare-bone core without menus or toolbars, using special keys and the mouse to navigate within Celestia. Many Linux distributions maintain a copy of Celestia in their software repositories, see the repository content lists for your distribution. There is also an experimental AppImage file which is a single executable file for the GTK interface with the program, data content and most of the libraries needed to run it on many Linux distributions. It can be found at https://download.opensuse.org/repositories/home:/munix9/AppImage/. Simply download the AppImage file, change the file properties to executable, and execute the program. The program is not limited to the planetary textures and spacecraft found in the program release, but can access additional Celestia content. The AppImage program responds to the Command Line Options of its GTK user interface. By using the dir and extrasdir options you can create directories to access additional data, images, scripts and models from the AppImage.
     Note: You must separately obtain and install openGL and the libraries needed for each user interface. There are several optional helper programs to Celestia - these may/may not have been compiled into your Celestia version. They will require additional libraries. These will be found in your Linux distribution's software repository. Often the package manager (software install program) for a Linux distribution has automated these repositories, so installing Celestia will automatically call for, download and install the additional needed packages.
     Note: In the case of Ubuntu and other Debian derivatives, if downloading directly from the distribution's repositories, Celestia is split into free and non-free versions because of their strict interpretation of how licensing should be handled. Both are needed for Celestia to work properly.
     - Developmental version 1.7.x can be found in two user interface styles. Qt is a more advanced, full windowed graphical user interface with menus, toolbars and bookmarks. It is available in Qt5 and Qt6 versions. SDL is a bare-bone core without menus or toolbars, using special keys and the mouse to navigate within Celestia. Versions are available for Debian, Ubuntu and openSUSE via the openSUSE Open Build Service. See the Celestia website download section for links and instructions. The files can also be directly downloaded from the software repository at https://download.opensuse.org/repositories/home:/munix9:/unstable/. There is also an experimental AppImage file which is a single executable file for the Qt interface with the program, data content and most of the libraries needed to run it on many Linux distributions. It can be found at https://download.opensuse.org/repositories/home:/munix9:/unstable/AppImage/. Simply download the AppImage file, change the file properties to executable, and execute the program. The program is limited to the planetary textures and spacecraft found in the program directories, it cannot access additional Celestia content.
   - macOS
     - Release version 1.6.x is available in the native macOS user interface. It can be downloaded from the Celestia website in the downloads section. It is also available from the Celestia GitHub repository. On the right side of the main page is a "Releases" section which provides a link to program releases. This link will provide a page of the available releases and a list of "assets" for each release which includes the macOS file. The file is a zipped bundle of the program, data files, planetary textures and simple spacecraft. Download the file, unzip it and place the contents into the proper macOS directories to access the program.
     - Developmental version 1.7.x is not available in the native macOS user interface. You must use the cross-platform Qt interface version. A user interface modified version of 1.7.x can be downloaded from the Celestia mobile website in the download section. It comes complete with data, planetary textures and models. It has its own release numbers and release schedule, and is slightly behind the code found in the Celestia GitHub repository.
   - iOS
     iOS is an Apple Inc. operating system used on iPhone, iPad, etc. Celestia has been ported to this operating system as a separate project. It is based on Celestia 1.7.0, but has its own release numbers, release schedule and additional code base. It comes complete with data, planetary textures and models. Release version 1.5.x can be downloaded from the Celestia mobile website in the download section. It can also be directly downloaded from the Apple App Store.
   - Android
     Android is a Google operating system used on many cell phones. Celestia has been ported to this operating system as a separate project. It is based on Celestia 1.7.0, but has its own release numbers, release schedule and additional code base. It comes complete with data, planetary textures and models. Release version 1.5.x can be downloaded from the Celestia mobile website in the download section. It can also be directly downloaded as an app from Google Play.
2. Command Line Options
   Celestia can be started either by clicking on its icon or by typing a command into a terminal window. Under Windows, the terminal window is often called a DOS window or CMD window or Powershell. When starting from the command line, a series of options (switches) can be used to modify the behavior of Celestia. These options are different depending on which interface Celestia was built for. Options used by the programming language are activated first, followed by application options. The options for the Celestia application are as follows:

   ### Windows (native)

   --dir path | Set the Celestia data installation directory to path.
   --conf file | Set the Celestia configuration file to file where file contains both the path and filename.
   --extrasdir path | Use additional "extras" directory at path. This option may be used multiple times.
   --url url/file | Start at the given cel:// URL or start with the given script file at path and filename.
   --fullscreen | Start Celestia in full screen mode.
   --once | Send the command line to a running instance of Celestia. If no running instance exists, a new one is started.
   --verbose | Output run and/or debug information.
   Note: Option names are preceded by two dashes (hyphens). Options which have a settable value must have a space between the option name and value.
   Note: Without options being set, upon startup the current (console window) directory is assumed to be the installation directory. File paths may be either an absolute file path or a relative file path from the installation directory.
   Note: Cel urls from other operating systems may fail on Windows. Some characters in the url are being intercepted by Windows for internal use. To overcome this problem, place the url in double quotes --url "url".

   ### KDE

   --dir=path | Set the Celestia data installation directory to path
   --conf=file | Set the Celestia configuration file to file where file contains both the path and filename.
   --extrasdir=path | Use additional "extras" directory at path. This option may be used multiple times.
   --fullscreen | Start Celestia in full screen mode.
   --nosplash | Disable the startup splash screen.
   --help | Display command line help.
   url/file | Start at the given cel:// URL or start with the given script file.
   Note: Option names are preceded by two dashes (hyphens). Options which have a settable value may have either a space or an = sign between the option name and value.
   Note: File paths may be either an absolute file path or a relative file path from the current (console window) directory.

   ### GTK/Gnome

   -d, --dir=path | Set the Celestia data installation directory to path.
   -c, --conf=file | Set the Celestia configuration file to file where file contains both the path and filename.
   -e, --extrasdir=path | Use additional "extras" directory at path. This option may be used multiple times.
   -f, --fullscreen | Start Celestia in full screen mode.
   -s, --nosplash | Disable the startup splash screen.
   -h, --help | Display command line help.
   url | Start at the given cel:// URL.
   Note: Option names with multiple characters are preceded by two dashes (hyphens). Options with a single character are preceded by a single dash (hyphen). Option names with multiple characters which have a settable value may have either a space or an = sign between the option name and value. Option names which are a single character may only have a space between the option name and value.
   Note: File paths may be either an absolute file path or a relative file path from the installation directory. The only exception is option dir which may have a relative file path from the current (console window) directory.

   ### Qt

   --dir=path | Set the Celestia data installation directory to path.
   --conf=file | Set the Celestia configuration file to file where file contains both the path and filename.
   --extrasdir=path | Use additional "extras" directory at path. This option may be used multiple times.
   -l, --log=file | Write a log file at file where file contains both the path and filename.
   -u, --url=url/file | Start at the given cel:// URL or start with the given script file at path and filename.
   --fullscreen | Start Celestia in full screen mode.
   -s, --nosplash | Disable the startup splash screen.
   -v, --version | Output the version number of Celestia.
   -h, --help | Display command line help.
   Note: Option names with multiple characters are preceded by two dashes (hyphens). Options with a single character are preceded by a single dash. Options which have a settable value may have either a space or an = sign between the option name and value.
   Note: File paths may be either an absolute file path or a relative file path from the current (console window) directory.

3. Basic Navigation
   Celestia will start up in a window, and if everything is working correctly, you'll see Earth in front of a field of stars. Displayed on-screen, is some information about your target (Earth), your speed, and the current time (Universal Time, so it'll probably be a few hours off from your computer's clock).
   Right drag the mouse to orbit Earth and you might see the Moon and some familiar constellations. Left dragging the mouse changes your orientation also, but the camera rotates about its center instead of rotating around Earth. Rolling the mouse wheel will change your distance to Earth--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.
   When running Celestia, you will usually have some object selected. Currently, it's Earth, but it could also be a star, moon, spacecraft, galaxy, or some other object. The simplest way to select an object is to click on it. Try clicking on a star to select it. The information about Earth is replaced with some details about the star. Press G (or use the Navigation menu), 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 Sun. Right click on the sun to bring up a menu of planets and other objects in the solar system. After selecting a planet from the menu, hit G again to travel toward it. Once there, hold down the right mouse button and drag to orbit the planet.
   The Tour Guide is a list of some of the more interesting objects you can visit in Celestia. Select the Tour Guide option in the Navigation menu to display the Tour Guide window. Choose a destination from the list, click the Goto button, and you're off.
   That covers the very basics. For a more in-depth look at Celestia and the controls available to you, download the "Celestia User's Guide" (written by Frank Gregorio), available in several languages, from: https://celestiaproject.space/guides.html.
4. Star & Solar System Browser
   The Navigation menu contains Solar System Browser and Star Browser options.

   ### Star Browser

   By default, the Star Browser window displays a table of the 100 nearest stars, along with their Distance, Apparent and Absolute Magnitude, and Type. Clicking on the column headers will sort the stars. The table is not continuously updated, so if you travel to another star, you should press the Refresh button to update the table for your current position. The radio buttons beneath the table let you switch between viewing a list of Nearest, Brightest, or With planets stars.
   As with the solar system browser, clicking on any star name in the table will select it. Use this feature along with the Center and Go To buttons to tour the stars visible from any night sky in the galaxy.

   ### Solar System Browser

   The Solar System Browser displays a window with a tree view of all the objects in the nearest solar system (if there is one within a light year of your current position.) Clicking on the name of any object in the window will select it. You can then use the Center or Go To buttons to display that object in the main Celestia window.
5. Selecting Objects by Name
   Celestia provides several ways to select an object by name:
   - Choose Select Object from the Navigation menu, type in the object name, and click OK
   - Press Enter, type in the entire object name, and press Enter again
   - Press Enter, type in the first few characters of the object name, press the Tab key to move through the displayed listing until the object is highlighted, then press Enter again
   You can use common names, Bayer designations or catalog numbers for stars. Celestia currently supports the HIP, HD and SAO catalogs. Catalog numbers must be entered with a space between the prefix and the catalog number.
6. User-modifiable Elements
   You can modify how Celestia starts up each time you run it, by defining your own start-up settings. Simply open the file "start.cel" in a plain text editor and follow the in-file instructions. Also, view the celestia.cfg file in a plain text editor to see additional settings.
   Note: It is highly recommended that you create backup copies of these files before editing them.
   Celestia allows you to easily add real, hypothetical, or fictional objects by creating new catalog files. It is not recommended that you alter the built-in data files; nearly all desired modifications and additions can be made by placing new catalog files in Celestia's extras folders. There are three types of catalog files:
   - ssc (solar system catalog: planets, moons, spacecraft, etc.)
   - stc (star catalog)
   - dsc (deep sky catalog: galaxies, star clusters, and nebulae)
   All three types of catalog file are text files that can be updated with your favorite text editing program.
7. Additional Celestia Content
   The files for Celestia have grown to a large size, causing some distributions to split the files into two separate files - one for the program and one for the data/models/textures. Most releases of version 1.6.x are of a single file, and the GitHub source is one single site. Beginning with version 1.7.x the Celestia GitHub repository has been split into two sites, the original GitHub repository that contains the program (CelestiaProject/Celestia), and a new content repository (CelestiaProject/CelestiaContent). In order for Celestia 1.7.x to run, the files from both sites must be combined. Many distributions provide the separate data content files already pre-packaged. If these are not available, then go to the Celestia content repository and click on the green "Code" button in the upper right corner. Select the download as zip file option, and download the content file. Unzip this file to find the CelestiaContent-master directory. The directories that must be added to the main Celestia program (install) directory are:
   * data
   * extras
   * extras-standard
   * models
   * textures
   * warp
   Note: If multi-language support is desired, the CMAKE program can be run to generate language files from the po directory and individual languages can be installed.
   Celestia also has a wide and talented user community. This community is constantly updating content, producing highly detailed models (many are spacecraft), improved planetary textures and incorporating recent astronomical discoveries. Their work can be found on multiple websites. The Celestia Forum has many spacecraft models and other addons for Celestia. This includes highly detailed models of the International Space Station, the Chinese Space Station Tiangong, the Hubble Space Telescope, the James Webb Space Telescope and most of the spacecraft that have been flown or are in development. The Celestia MotherLode has spacecraft, including ships from fictional universes such as Star Trek, Star Wars, Babylon 5 and 2001. The Celestia Mobile site has a collection of spacecraft and astronomical objects found under the "Addons" tab. The Celestia Origins project seeks to update the astronomical database of Celestia with planetary/moon locations, recently discovered moons and other objects. There are several efforts to add a large database of newly discovered exo-planets to Celestia. Searching for Celestia on the internet will give multiple sites to find additional content. Links for some of these websites can be found in the Resources section below.
8. Known Issues
   For up-to-the-minute answers to some common problems encountered when running Celestia, please view either the FAQ under Table of Contents (to the left) or take a look at the "Celestia User's FAQ" located on the Celestia User's Forum: celestiaproject.space/forum.

# Celestia Controls

This list of controls was current as of Celestia version 1.6.0. If you notice that a command is missing or incorrect, please write a message in the Celestia Bugs forum, located at: https://celestiaproject.space/forum/viewforum.php?f=3.
"Left" and "Right" designate the mouse button which has to be pressed.

## Mouse Controls description

Left Drag | Camera orientation -- Up/Down/Left/Right (also Up & Down arrow keys, and 2/8/4/6 on the Number Pad with NumLock enabled)
Right Drag | Orbit selected object (Shift+Arrow keys)
Left+Right Drag left/right | Roll view left/right (Left/Right arrows)
Left+Right Drag up/down | Adjust distance to selection (Home/End)
Scroll Wheel | Adjust distance to selection (Home/End)
Ctrl+Left Drag up/down | Adjust distance to selection (Home/End)
Shift+Left Drag | Field of View (FOV) adjust. (also . and ,)
Middle Button | Field of View (FOV) toggle -- between 45 degrees and previous setting
Left Click on object | Select object (Enter key -- by object name)
Left Click on no object | Deselect currently selected object
Left Double Click on object | Select and Center object
Right Click on object | Bring up context menu

## Keyboard Controls description

### Navigation

1 - 9 | Select planet around the nearest star
0 (zero) | Select parent star of current planet or system
H | Select Sol, our sun (Home system)
C | Center the selected object on the display
G | Goto selected object
F | Follow selected object
T | Track selected object (keep object centered on the display)
Y | Sync Orbit selected object at a rate synced to its rotation
: | Lock two objects together as one (select object #1, press "f", select object #2, press ":")
" | Chase selected object (orientation is based on the object's velocity)
Shift+C | Center/orbit--center the selected object without changing the position of the reference object
Ctrl+G | Goto surface of selected object
Ctrl+F | Alt-azimuth mode (toggle). Used with Ctrl-G (Goto surface). The Left & Right Arrow keys become Yaw Left / Yaw Right
Home | Move closer to object
End | Move further away from object
* | Look back (Reverse view 180 degrees)
Backspace | Select parent of current object or clear the selection: - If selection is a location, select the parent object - If selection is an object, select the parent object / star - If selection is a star, clear the selection
Esc | Cancel: scripts, Goto, Follow, Track, Lock, Sync Orbit

### Navigation via Arrow Keys

Up Arrow | Pitch down (moves object Up)
Down Arrow | Pitch up (moves object Down)
Left Arrow | Roll left (rolls object Right)
Right Arrow | Roll right (rolls object Left)
Shift+Left Arrow | Orbit object: right (rotates object Left)
Shift+Right Arrow | Orbit object: left (rotates object Right)
Shift+Up Arrow | Orbit object: down (rotates object Up)
Shift+Down Arrow | Orbit object: up (rotates object Down)

### Navigation via number Pad Keys (with NumLock active)

8 | Pitch down (moves object Up, also Down arrow)
2 | Pitch up (moves object Down, also Up arrow)
7 | Roll left (rolls object Right, also Left arrow)
9 | Roll right (rolls object Left, also Right arrow)
5 | Stop rotation
4 | Yaw left
6 | Yaw right

### Motion (Spaceflight)

A | Increase velocity
Z | Decrease velocity
Q | Reverse direction
X | Set direction toward center of screen
S | Stop motion
F1 | Stop motion
F2 | Set velocity to 1 km/second
F3 | Set velocity to 1,000 km/second
F4 | Set velocity to speed of light (1 c/second)
F5 | Set velocity to 10x the speed of light (c)
F6 | Set velocity to 1 AU/second
F7 | Set velocity to 1 light year/second

### Time Control

Spacebar | Pause/Resume the flow of time and scripts (toggle)
J | Reverse/Forward time (toggle)
\ | Set time: 1x forward (norm), cancels faster/slower x factors
L | Change time rate: 10x faster
K | Change time rate: 10x slower
Shift+L | Change time rate: 2x faster
Shift+K | Change time rate: 2x slower
! | Set time to current date and time
? | Display light-travel delay between observer / selected object
- (hyphen) | Add / Subtract light-travel delay from current simulation time

### What Label to display (on/off toggles)

E | Galaxies
Shift+E | Globulars
B | Stars
P | Planets
Shift+P | Dwarf Planets
M | Moons
Shift+M | Minor Moons
W | Asteroids
Shift+W | Comets
N | Spacecraft
= | Constellations
& | Locations

### What Items to Render / Display (on/off toggles)

U | Galaxies
Shift+U | Globulars
^ | Nebulae
Ctrl+A | Atmospheres
I | Clouds
Ctrl+L | Night side planet lights (light pollution)
Ctrl+T | Comet tails
Ctrl+E | Eclipse shadows
Ctrl+B | Constellation boundaries
/ | Constellation diagrams
; | Earth-based equatorial coordinate sphere
Ctrl+K | Markers (placed on objects)
O | Orbits (toggle ON/OFF ALL selected orbits in the Preferences/General dialog box)

### Render / Display Options

{ | Decrease Ambient Light
} | Increase Ambient Light
( | Decrease Galaxy Light Gain (Dimmer)
) | Increase Galaxy Light Gain (Brighter)
[ | Decrease Magnitude Limit: - If AutoMag OFF: Decrease limiting magnitude (fewer stars) - If AutoMag ON : Decrease limiting magnitude at 45 deg FOV
] | Increase Magnitude Limit: - If AutoMag OFF: Increase limiting magnitude (more stars) - If AutoMag ON : Increase limiting magnitude at 45 deg FOV
Ctrl+Y | Toggle Auto Magnitude (auto adaptation of star visibility to FOV)
, | Narrow Field Of View [FOV] (also Shift+Left Mouse Button Drag)
. | Widen Field Of View [FOV] (also Shift+Left Mouse Button Drag)
Ctrl+X | Toggle Antialias lines (ie. orbits)
Alt+Enter | Toggle Display mode (Full-Screen / Windowed)
Ctrl+P | Mark selected object (Marker display must be active -- Ctrl+K)
Ctrl+V | OpenGL Render Paths -- Cycle through the paths supported on your graphics card
+ | Toggle Planet Texture Type (Artistic / Limit of Knowledge)
% | Toggle star color table
Ctrl+S | Cycle the Star Style (points / fuzzy discs / scaled discs)
V | Cycle the Info text verbosity ( Terse / Verbose / None )
Ctrl+W | Toggle Wireframe mode

### Multiview Options

Ctrl+U | Split view vertically into left and right sections
Ctrl+R | Split view horizontally into upper and lower sections
Tab | Cycle through all active views
Delete | Delete active view
Ctrl+D | Delete all views except active one (reset to Single view)

### Other Functions

Ctrl+C | Copy location URL to clipboard (Cel:// URL)
Ctrl+Insert | Copy location URL to clipboard (Cel:// URL)
F10 | Capture Image to file (screenshot)
Shift+F10 | Capture Movie to file (video)
F11 | While in Movie Capture: Start / Pause capture
F12 | While in Movie Capture: Stop capture
~ | Toggle debug console (display "file loading" information) Use to debug texture loading problems. Up/Down arrow keys scroll list
` | Toggle display of "frames per second" (FPS) being rendered
Ctrl+O | Display "Select Object" dialog box
@ | Edit Mode toggle (to assist in the placements of objects)
Enter | Activate object/location name entry mode - Esc to exit - Type an object or location name and press Enter - Type a partial name then use Tab / Shift+Tab to highlight an item Enter will then select the highlighted item

## Joystick Controls description

F8 | Toggle Joystick control
X axis | Yaw Left/Right
Y axis | Pitch Up/Down
L trigger | Roll Left
R trigger | Roll Right
Button 1 | Move slower
Button 2 | Move faster

## Mac specific controls

### What Orbits to Display

O | Orbits (toggle ON/OFF ALL selected orbits in the Preferences/General dialog box)
Shift+Cmd+P | Planet orbits
Shift+Cmd+M | Moon orbits
Shift+Cmd+A | Asteroid orbits
Shift+Cmd+C | Comet orbits
Shift+Cmd+S | Spacecraft orbits

### Unsorted

Cmd+Left Drag | Adjust distance to selection (Home/End)
Cmd+L | Open Go To Object dialog box
Cmd+B | Open Browser
Cmd+T | Open Set Time dialog box
Cmd+F | Toggle full screen mode
Cmd+E | Open Eclipse Finder
Cmd+C | Copy the cel:// URL of current position
Cmd+V | Paste last cel:// URL copied
Cmd+D | Add selected object to Favorites
Shift+Cmd+D | Open Favorites dialog box
Cmd+] | History (Forward)
Cmd+[ | History (Backward)
Cmd+M | Minimize Celestia window

## Linux specific controls

Alt+S | GotoSurface
Alt+F | Alt-azimuth mode (toggle). Used with Ctrl-G (Goto surface). The Left & Right Arrow keys become Yaw Left / Yaw Right

# Celestia FAQ

## Graphics

1. The Earth and other planets look strange. They have weird colors or do not look like globes. How can I fix this?

   ### Answer:

   Your graphics drivers might be incompatible with Celestia. Try the following, in this order:
   - Update the graphics drivers to the most recent version. See section »Installation of new graphic card drivers on Windows«.
   - Switch to "Basic" or "MultiTexture" render paths: type [Ctrl+V] several times.
   - Disable Celestia's vertex shaders: edit celestia.cfg (with a plain text editor) to remove the # at the start of this line # IgnoreGLExtensions [ "GL_ARB_vertex_program" ]
   - Disable 3D hardware graphics acceleration. You find that under Windows in the display properties.
   - If none of these work for you, please ask for help in the Celestia Help Forum.
2. Celestia is drawing planets and moons bright red. Why?

   ### Answer:

   Your computer's graphics drivers are obsolete. Celestia makes use of the most advanced features of OpenGL that the graphics driver claims to support. Modern drivers require that the program (Celestia) specifies the version of vertex shader routines that it uses. Obsolete drivers don't recognize that specification. When vertex shaders generate an error message, Celestia draws the object bright red.

   ### Solution:

   Download and install current drivers for free from the Web site of the manufacturer of your graphics hardware.
   If you are using Windows make sure that you have disabled the feature to download graphics drivers from Microsoft. Those drivers have an outdated version of OpenGL included. Always use graphic card drivers from either the graphics card manufacturer or better directly from graphics chip manufacturer (i.e. NVIDIA, ATI/AMD, Intel, ...).
   Whenever you upgrade Microsoft's DirectX software, you must upgrade or reinstall the graphics hardware manufacturer's graphics drivers afterward. Installing DirectX installs Microsoft's copies of the drivers, which usually are several generations old.
   For correct installation of drivers see point »Installation of new graphic card drivers«.
   a) For PCs running Windows with plugin graphics cards, you can download the drivers for free from the Web site of the manufacturer of your graphics card. Make sure full hardware acceleration is enabled in your display properties.
   b) For laptops and desktops running Windows with embedded graphics chipsets, you usually must download the most recent drivers from the Web site of the manufacturer of your computer. Sometimes generic drivers are available from the manufacturer of the graphics chipset.
   c) For Apple PPC and Intel computers running MacOS X, you must upgrade to the most recent version of the operating system. Updated drivers usually are not available separately.
   Apple's OpenGL on MacOS X often has serious bugs which sometimes are not fixed in the most recent release of MacOS. You must report those problems to Apple, otherwise they will not get fixed.
   d) For computers running Linux, you usually can download the drivers for free from the Web site of the manufacturer of your graphics card.
   ATI's fglrx drivers for Linux often have serious bugs. Try to use the driver shipped with the most recent version of Xorg's X server software.
3. The Moon is purple, blue and red. Why?

   ### Answer:

   Your graphics chipset and its OpenGL drivers aren't drawing bumpmaps and normalmaps properly: their OpenGL routine "GL_ARB_vertex_program" is defective. (This is often seen with the newer Intel graphics chips.)

   ### Solution:

   Install an updated graphics driver or try the workarounds described below.
   Workaround 1: Turn off Celestia's advanced display features.
   Type [Ctrl+V] several times to select "Basic" or "Multitexture" render paths instead of the OpenGL Vertex programs. This disables the use of vertex and shading programs temporarily. If this does improve things after you've followed the previous suggestions, then you need to do the next step:
   Workaround 2: Tell Celestia to ignore specific features that your OpenGL library claims (falsely) to support. To do this, edit celestia.cfg. Remove the # that's in front of the line
   # IgnoreGLExtensions [ "GL_ARB_vertex_program" ]
   (This avoids system lockups experienced under MacOS X 10.3.5 with ATI cards, and purple moons with Intel chips, for example. Intel chips don't have support for some of the graphics routines used by Celestia.)
   Celestia's Help menu "OpenGL Info..." lists all of the routines in your OpenGL library. You might consider adding equivalent IgnoreGLExtensions lines for other suspicious routines.
4. I want to see all possible Celestia eye candy. What kind of graphics card should I get?

   ### Answer:

   The short answer is the following:
   Any graphics card with at least 128MB of memory and support for OpenGL 2.0 pixel shaders will be able to show everything that Celestia is visually capable of.
   Look for a graphics card that advertises either support for Direct3D shader model 2.0 or higher. Almost all graphics cards being sold today meet this requirement, albeit with varying degrees of performance. High-end NVIDIA and ATI cards will provide the best experience in Celestia. NVIDIA's OpenGL drivers have tended to have fewer bugs than ATI's.
   Here are some recommendations for cards:
   - ATI Radeon HD series
   - GeForce 8xxx, 9xxx and GTX 2xx series
5. How will Celestia perform on my system?

   ### Answer:

   a) Only NVIDIA 5000 series or greater (e.g. 6000, 7000, 8000, 9000, 250) cards with 128MB of memory or more will show all of the eye candy drawn by Celestia v1.4.0 or later.
   ATI Radeon 9500 and above, including the X series, are comparable to NVIDIA FX 5nnn series cards in functionality, although performance differs. However, not all of the eye candy drawn by Celestia is compatible with them.
   b) Graphics cards with drivers that support OpenGL v2.0 will show all. Graphics cards that support only v1.4 will show most, but not all, eye candy.
   E.g. NVIDIA GF4 Ti 4xxx series cards cannot show smooth shadow borders. Starting with Celestia v1.4.0, smooth shadow borders can be drawn by any card which supports OpenGL v2.0.
   c) Other cards work, but with various additional limitations.
   Some specific limitations:
   - NVIDIA MX cards cannot shadows of rings on planets, although they can draw shadows of planets on rings.
   - ATI Rage cards cannot show specular highlights or bumpmap shadows.
   - Textures on Rings, 3D Mesh models, and moving Clouds are limited to the size of your card's texture buffer. This limitation does not apply to the surface textures of spherical planets and moons.
   Therefore...
   Most ATI cards, including the X series, cannot show surface texture images larger than 2K (2048 pixels on the longer side) on a side on Rings, on 3D Mesh models, or on moving Clouds. Unfortunately, some addons include 4K (4048) pixel textures. Those addons only work with NVIDIA 4nnn, 5nnn, 6nnn and 7nnn cards and with ATI X1800 and above with ATI's most recent graphics drivers. Those cards have 4K texture buffers.
   In order for Celestia to be able to show bumpmap shadows and specular reflections, your card's OpenGL library must support OpenGL v1.4. In particular, it needs to include "GL_ARB_vertex_program".
6. Why does the illumination level in Celestia not fall off the farther from the Sun I go - surely it should be very dark by the time I get to Pluto?

   ### Answer:

   The human eye can adapt to a very wide range of illuminations, so it wouldn't be as dark out there as you think – about the level of moderate indoor lighting, in which you can see very well. At the other end of the scale, your computer monitor is physically incapable of generating the brightness of illumination that pertains on the inner planets.
   Fortunately it doesn't need to, since all that would happen would be that your pupils would constrict to reduce the incoming light to a more comfortable level.
   So in summary:
   a) There's no way Celestia can display "realistic" brightness on your computer screen,
   b) such "realism" is unnecessary because your eyes merely adapt to compensate.
7. Celestia's galaxies are ugly, dim, grey blobs. How can I get colorful galaxies that look like the real things?

   ### Answer:

   The real things are dim, grey blobs. Your eyes are not sensitive to color at the very low light levels emitted by distant galaxies. Many of the colorful pictures you're used to seeing are enhanced by long exposures on sensitive color film. Others are imaginative "false color" combinations of narrow-band CCD images designed to make visible the specific features of interest to the investigator. The colors of those pictures aren't realistic at all.

   ### Solution:

   You can add a colorful object to Celestia by creating a 3DS model with appropriate images as surface textures. Define it as a Nebula in a DSC file. Use the Search command in the Celestia "Development" and "Add-On" forums to find examples.
   Galaxy brightness can be increased by typing a [)] (Shift+0) or decreased by typing a [(] (Shift+9) (on english keyboard layout).
8. Positions on Mars are on the opposite side of the planet or bumps seem to be half a world away from the mountains or it's dark where it should be daylight. Why?

   ### Answer:

   You have a misaligned map.
   Celestia requires that all maps have 0 degrees of longitude in the center, with 180 degrees of longitude at the edges. All of the surface texture image maps of all of the moons and planets that come with Celestia have this alignment.
   In contrast, many maps of Mars were created with 0 degrees of longitude at the left and right edges, and with 180 degrees of longitude in the center.
   Using a map with 0 at the edge would cause the symptoms you describe.

   ### Solution:

   You need to find a map that's properly aligned or you need to cut the map in half and exchange the halves.
   For example with Photoshop's 'Offset' filter is quite easy to modify maps that are misaligned by 180 degrees. In Photoshop CS2, select Filter/Other/Offset and set the horizontal offset amount to half the texture width.
9. Why are some texture maps upside down and backward?
   I compared the Celestia textures for Venus, Ida and Miranda with some I found in a book or on the Web, and Celestia's maps are upside down.

   ### Answer:

   Many sources for planetary maps (such as the USGS) use a mapping convention called "ecliptic north" – the north pole of any planet or asteroid is defined as being whichever rotational pole points north of the plane of the ecliptic (the plane of the Earth's orbit around the Sun). Each planet or asteroid can then be classified as a "direct" rotator, if it rotates in the same direction as the Earth when observed from above its north pole (i.e. counterclockwise); or as a "retrograde" rotator, if it rotates in the opposite direction.
   In contrast, Celestia uses an equally valid mapping convention called "rotational north" – north is defined as being the pole around which the planet appears to rotate counterclockwise, irrespective of that pole's orientation relative to the ecliptic.
   For direct rotators, this difference is irrelevant – "north" turns out to be the same direction in both mapping conventions. But for retrograde rotators, Celestia's north pole corresponds to ecliptic south – so you will find many maps of retrograde rotators like Venus, Ida and the moons of Uranus that appear to be upside down relative to those in Celestia.

   ### Solution:

   If you want to convert such maps for use in Celestia, you'll have to turn them through 180 degrees.
10. My planet's rings are drawn as a featureless oval. It used to work. What's wrong?

    ### Answer:

    For most graphics cards, the texture size limit is at least 2048. To find out how big this size is, use the "OpenGL Info..." option in Celestia's help menu. Near the beginning it has a line that starts with "Max texture size:".

    ### Solution:

    You need to use a smaller ring image, one that is no wider than the maximum texture size supported by your graphics card.
11. Problem on Ubuntu: Why does Celestia not have textures?

    ### Answer:

    The version of Celestia supplied in the package manager or the Add/Remove programs menu is broken. Celestia's textures are included in the package celestia-common-nonfree which is not listed as a dependency of the main program, so is not installed by default.

    ### Solution:

    To fix this issue, either install the celestia-common-nonfree package through the package manager, or type in a terminal window:
    sudo apt-get install celestia-common-nonfree
12. Older issues that should be solved
    These issues shouldn't normally happen with the recent Celestia version. But just in case IF they happen anyway, here are the solutions.
    Sometimes when Celestia captures an image of its window, there's an ugly bright rectangle in the picture. How can I get rid of it?

    > Sometimes a bright area is recorded where the file requestor menu or any other window overlaps Celestia's main window. This bug seems to be fixed since Celestia v1.4.0, but if it happens here are some tips for avoiding this problem.
    > a) The problem will often go away if you toggle "Show Galaxies" off and on again before you take your snapshot. Either use the Render/View Options menu or type the letter [U] twice before you press [F10].
    > b) Run Celestia in windowed mode, not full-screen. Drag the file requestor away from in front of the main window before you click on "Save".
    > c) If your graphics card supports it, you can connect a secondary display. Some CRTs are very inexpensive. Drag the file requestor to the other screen.
    > d) Use an external screen-dump command or program.
    > Windows includes a "print-screen" command. Under XP, you can use the keyboard combination [Ctrl+Print-Screen] to write the screen image to the clipboard. You can then use any Paint program and Paste the image into it.

    Sometimes a screenshot captured in Celestia will have multiple boxes around it, as if Multiview was on. How can I get rid of it?

    > This is a bug in Celestia. To make a good clean screenshot image, press [Ctrl + D] before you capture the image. This cancels Multiview.

    When I try to capture a picture or movie, the image is stretched out of proportion.

    > This sounds like a bug with anti-aliasing with older cards/drivers. Here are three things you can try...
    > 1. Check the OpenGL anti-aliasing setting of your graphics card. If it is on, try turning it off, or setting it to another option. This seems unrelated to the anti-aliasing setting inside of Celestia.
    > 2. Set your graphics card OpenGL options to "default".
    > 3. Get the most recent drivers for your graphics card.

## Installation of new graphic card drivers on Windows

1. General Information
   Be sure to use the following general procedure when installing new graphics drivers:
   - Download driver installation program from graphic chip manufacturer website (i.e. NVIDIA or ATI/AMD)
   - Use the Control Panel / Add or Remove Programs menu to delete the current graphics drivers.
   - Reboot your PC.
   - Cancel out of Windows' offer to install new drivers.
   - Run the Installation program for the new drivers.
   - Reboot
   - Configure desktop resolution and other desirable features.
   The two reboots are essential in order to cause the old low-level drivers to be deleted. Without those reboots, the old low-level drivers will not be deleted and the new installation will not work properly, although it may not generate any error messages.
   Next section shows in detail how to do it for an Nvidia card. The procedure is the same for cards by other vendors.
2. Uninstalling the NVIDIA Display Driver Software
   Note: It is highly recommended that you follow the steps in this section to completely uninstall the NVIDIA Display Driver software before updating to a new version of the software.
   To uninstall the nView software, follow these steps:
   - From the Windows taskbar, click Start > Settings > Control Panel to open the Control Panel window.
   - Double-click the Add/Remove Programs item.
   - Click the NVIDIA Display Driver item from the list.
   - Click Change/Remove.
   - Click Yes to continue.
     A prompt appears asking whether you want to delete all of the saved nView profiles.
     - If you click Yes, all of the nView software and all of your saved profiles will be deleted.
     - If you click No, the nView software is removed, but the profile files are saved in the Windows\nView directory on your hard disk.
   - Your system now restarts.
3. Installing the NVIDIA ForceWare Graphics Drivers
   - Follow the instructions on the NVIDIA website driver download page to locate the appropriate driver to download, based on your hardware and operating system. (You can already do this step, before you uninstall the old drivers.)
   - Click the driver download link.
   - The license agreement dialog box appears.
   - Click Accept if you accept the terms of the agreement, then either open the file or save the file to your PC and open it later.
   - Extract the zip files to a temporary folder on your PC.
   - Open the NVIDIA driver installation .EXE file to launch the NVIDIA InstallShield Wizard.
   - Follow the instructions in the NVIDIA InstallShield Wizard to complete the installation.
   - Reboot your system, if it hasn't already been rebooted by the installation program.
4. Graphics driver update procedure for Laptops
   Note: Older Laptops/Notebooks will need a driver from the web site of the manufacturer of the laptop (not from NVIDIA)!
   Depending on the brand of laptops and the used card, it may take special action to update graphics drivers by the standard ones from the NVIDIA site. Normally, for these laptops, one has to update the drivers from the vendor's site instead. The reason is that in such cases, the laptop requires a modified .inf file together with the standard driver. This typically happens in case of NVIDIA GO graphics cards!
   For example only most recent DELL machines work with the standard drivers from the NVIDIA site. These cases are listed explicitly by NVIDIA ...
   A typical signature for the situation is a message like the following during the installation of the standard NVIDIA driver:
   "NVIDIA setup program could not locate any drivers that are compatible with your current hardware. Setup will now exit."

   ### Solution:

   a) Download the drivers from your laptop manufacturer. b) Try what is described below if a) doesn't work (you are at your own risk).
   Note: If you are using what the below mentioned sites are offering we take no responsibility if anything goes wrong, you should know what you are doing and carefully read all instructions first before using the instructions given there.
   There is a site where the appropriately modified .inf files are offered, such that the standard NVIDIA driver update may be loaded without complaints by the particular laptop.
   http://www.laptopvideo2go.com/
   Besides offering Basic info and a FAQ this site also offers step-by-step instructions for VISTA.

## Crashes

1. Celestia crashes my computer.

   ### Problem:

   I can install it, no problem, but it won't even start up, it loads, then freezes. Then it crashes my computer, forcing it to restart.

   ### Solution:

   These kind of problems usually are caused by buggy graphics drivers. Please install the most recent drivers available for your graphics card and try again. Windows users see point »Installation of new graphic card drivers«.
2. Celestia crashes, what it draws is messed up or it's extremely slow. What can I do?

   ### Answer:

   Shut down all background programs on your system before running Celestia (i.e. antivirus software, multimedia software such as REAL Player, Musicmatch, etc.).
   Graphics programs are notorious for consuming system resources and even the best of graphics cards are better off without competing for those resources.
   Celestia makes use of the most advanced features of OpenGL that your computer's graphics driver claims to support. Many older OpenGL implementations have serious bugs.
   Here are some options for improving Celestia's display:
   - Make sure full hardware acceleration is enabled in your display properties.
   - Upgrade to the most recent drivers for your graphics card. Download them for free from the Web site of the manufacturer of your card, not from Microsoft, since those have only older implementations of OpenGL incorporated.
3. Celestia still crashes, draws funny stuff or is extremely slow. What can I do?

   ### Answer:

   Report the exact circumstances and details of your system, graphics hardware and software in the Celestia Bugs forum.
   Celestia runs on many different hardware and software configurations. It is not appropriate to ask people to guess what you have. For example:

   ### Problem:

   Celestia crashes when I look at Saturn with Ring Shadows enabled.

   > System: 2 GB 1.95 GHz Core2Duo, Windows XP SP3
   > Graphics: 256MB NVIDIA GeForce 7950 GT, ForceWare 169.21, OpenGL 2.1.2
   > Program: Celestia v1.6.0

   If you're running Windows, details are usually available in the Control Panel's System Properties menu.
   Some of the graphics information can be found in Celestia's Help menu under "OpenGL Info..." Under Windows more details can be found in the Control Panel's Display Properties menu.
   You can also report bugs on the GitHub bug tracker; but before you do so, please check in the Celestia Bugs forum if it has already been reported or solved.
4. Why does Celestia always use 100% of the CPU?

   ### Answer:

   Celestia uses 100% of the CPU if it cannot finish recalculating what's shown in its window before your computer decides it's time to refresh the screen.
   Celestia has to recalculate the positions and visibility of everything you see in its window every time your system refreshes its screen. If you have set the screen refresh rate to be 75Hz, then Celestia has to recalculate everything in 1/75 of a second. If it finishes recalculating everything before the screen is refreshed, then it will use less than 100% of the CPU. If it takes longer, then it will use 100% of the CPU and Celestia will redraw its window more slowly than the screen's refresh rate.
   In a dual processor or dual-core system or in a hyperthreaded system simulating a dual processor system, 100% of one of the CPUs is shown as 50% of total system usage. The calculations in Celestia are single-threaded and cannot make use of more than one CPU at a time.
   Type a [`] (= backslanted apostrophe = accent grave) to enable Celestia's fps (frames per second) display in the lower left corner. If you have a keyboard that supports diacritical marks, then you may need to type a [SPACE] after the [`].
5. How can I make Celestia use less CPU time?

   ### Answer:

   On most systems Celestia will use no CPU time if its window has been iconized or minimized. (Under Windows, click on the icon in the upper right corner of Celestia's window which has an underscore in it.)
   Also check if vsync is enabled in the Windows control panel (this is the default setting.) If vsync is not enabled, Celestia will render frames as fast as it can, even if this is faster than the rate at which the monitor can display them.
   You also can make Celestia use less of the CPU if you ask it to draw less. Some ways to do this are:
   - reduce the screen refresh rate
   - reduce the size of the window
   - reduce the size of objects drawn in the window so fewer stars and galaxies are obscured
   - reduce the number of stars and galaxies being obscured by turning down the limiting magnitude (type a [ several times) or by disabling them entirely
   - reduce the number of objects being drawn by loading fewer addons.
   Otherwise, consider upgrading your CPU so more can be calculated between screen refreshes. Upgrading the graphics card will help somewhat, depending on how many OpenGL functions get moved from software into hardware.

## Features

1. Why are my favorite stars not in Celestia?

   ### Answer:

   Celestia's primary star catalog is based on the Hipparcos database of stars with accurately measured distances. Hipparcos was not used to measure the distances to many dim, variable or close double stars.
   More recent versions of Celestia include all of the stars within 20 LY of the Sun, as well as about 200 double stars. (There are actually many more double stars than that, but relatively few have had their orbital parameters accurately measured.)
   Another possibility is that Celestia does not know this name of the star that you are looking for. A lot of stars have more than only one name/designation, some even more than 30. If you can't find the name that you are looking for, try an online resource like SIMBAD to find other names for the star.

   ### Solution:

   Someone may have created an Add-on that includes your stars, though. So you could try to look for it in the Add-on repository. Or consider creating the necessary STC file yourself and contributing it.
2. Stars with HIP or HD designations sometimes show up in the "tab completion" line and sometimes do not. What's going on?

   ### Answer:

   Only quoted Star "names" are shown in the tab completion line. Stars that have only a HIP catalog number are not listed in the tab completion line. When you want to select a Star that has only a HIP or HD catalog number, you must type its complete designation, including a space between HIP (or HD) and its number:
   [return]
   HIP 111111
   [return]
   Strings which only match entries in the binary stars.dat database or in one of the cross-index databases for HD and SAO designations are not shown by the tab-completion code. There are too many of them. Only names which are in an object's quoted textual name string in a textual catalog (SSC, STC or DSC) are listed by the tab-completion code.
   A confusion factor is that some Stars have HIP designations specified as their quoted names, often with no space between HIP and the number. Only these quoted HIP names are shown in the tab completion line. Some examples are in /data/visualbins.stc.
3. Why are there no stars in other galaxies than the Milky Way?

   ### Answer:

   Up to version 1.5.1 Celestia had technical limitations which prevented it from drawing stars beyond a distance of about 16,000 LY from the sun.
   Since version 1.6.0 Celestia is technically capable of displaying stars without a distance limitation. However, since Celestia is scientifically orientated only stars that have a precise measurement of their position are included in the star database of the official releases.
   With increasing distances of the stars from the Earth the measuring error of a star position gets huge, so it is not possible to exactly say where the star should be. Those stars are not included in Celestia and this criterion is also the reason why there are no stars displayed in other galaxies.
4. I want to write some scripts for Celestia. How can I do it?

   ### Answer:

   A)
   Celestia includes a very simple scripting language of its own which understands commands like "go here, look there, set flag, display text". These commands should go into a file with the filetype .CEL
   - An example .CEL script is Celestia's own start.cel, which is on your computer in Celestia's main directory.
   - A .CEL Scripting Guide is available in English and German on the Documentation Page of the Celestia MotherLode.
   - Selden's Celestia Resources website includes a list of some of the more recently added .CEL scripting commands, but they're rather cryptically organized.
   - Information can also be found in the Scripting section of the Celestia Wikibook.
   B)
   The Lua programming language is available for use in .CELX scripts. See http://www.lua.org/.
   - A few example Lua scripts for Celestia are available on GitHub at https://github.com/CelestiaProject/Celestia/tree/master/scripts.
   - A .CELX Scripting Guide is available in English on the Documentation Page of the Celestia MotherLode.
   - More information about CELX is available on Harald Schmidt's web site at http://celestia.h-schmidt.net/.
   C)
   You can use any language you want if it can pass commands to the operating system's command interpreter: It can run Celestia and tell it to run a .CEL Celestia script or .CELX Lua script.
   When invoked from a command line, Celestia can be passed the name of a .CEL or .CELX script to run at startup:
   ./celestia --url name-of-script.cel.
   When the command line includes the qualifier "--once", the command line will be passed to the running copy of Celestia instead of starting a new copy of the program. (note: two hyphens)
   ./celestia --once --url name-of-script.celx.
   Note: Scripts may be in any folder. But it helps with your organization of your Celestia folders if you keep them in a folder named /scripts/.
   For more information, please visit and contribute to the Celestia Scripting Forum.
5. How can I make Celestia work like a planetarium?
   I want to see how the sky should look from my backyard.

   ### Answer:

   - Select the body from which to observe; the Earth for example.
   - Use the GoTo menu to specify your Longitude and Latitude and GoTo there (lat & long are entered in decimal format – there are websites that convert to/from degrees/minute/seconds format.)
   - Type a [Y] = Sync Orbit (this locks you into position above the location you set)
   - Under Windows:
     - Type a [Ctrl+G] = GotoSurface
     - Type a [Ctrl+F] = change Arrow keys to AltAzimuth mode (This keeps the horizon level when panning left & right.)
     - Use the arrow keys to look toward the sky, you can adjust the field of view (FOV – how much sky you see at once) with the [,] & [.] keys.
   - Under Linux:
     - Type an [Alt+S] = GotoSurface
     - Type an [Alt+F] = change Arrow keys to AltAzimuth mode (This keeps the horizon level when panning left & right.)
     - Use the arrow keys to look toward the sky, you can adjust the field of view (FOV – how much sky you see at once) with the [,] & [.] keys.
   Activate the alt-azimuth coordinate display by selecting the "Horizontal grid" in the "View options" dialog.
6. Why can't I see Mir or Galileo? I know they're defined in Celestia.

   ### Answer:

   Mir along with other spacecraft models were modeled within an historical time frame and can only be viewed from their starting date to their ending date.
   Celestia will show those spacecraft only if you set the time to be somewhere between those two dates. Celestia does not display spacecraft if they are not in orbit at the time of the simulation.
   For example, Mir was launched on February 20, 1986, and reentered the Earth's atmosphere on March 23, 2001, at 05:55 GMT. This is controlled by Beginning and Ending directives in the definition of Mir in solarsys.ssc. If you remove those statements, Celestia will always draw Mir in orbit.
   You can override ending dates by opening the solarsys.SSC or other specific craft related .SSC files and placing a pound sign (#) in front of the ending date string. Then save the new setting. This way you can always view your installed Space Crafts. Consequently, removing the pound sign will return the craft to it's natural time frame.
7. Celestia's orbit for the ISS is out of date. How can I get a better one?

   ### Answer:

   The orbit of the ISS changes continuously in ways that are almost impossible to predict due to things like atmospheric drag, light pressure, cargo ship docking, etc. If you want an accurate orbit, you'll have to update it on a daily basis.
   ISS TLEs (Two Line Elements) are posted to the AMSAT SAREX mailing list regularly by "Dave Larsen PhD". See here: http://www.amsat.org/amsat/archive/sarex/31day/threads.html.
   Here are the ISS TLE orbital parameters for August 16th, 2004:
   ISS
   1 25544U 98067A 04229.23839543 .00019757 00000-0 15906-3 0 4532
   2 25544 51.6323 19.1941 0005251 117.9988 304.8582 15.70921896327755
   Grant Hutchison has provided a spreadsheet to convert TLEs into Celestia SSCs here: https://www.classe.cornell.edu/~seb/celestia/hutchison/spreadsheets.html#2.
   Also, don't forget that Celestia models the shape of the Earth using a spheroid. The actual shape of our planet is much more complicated.
   As a result, a view from the Earth's surface in Celestia is not accurate enough to show the correct path across the sky of satellites in low Earth orbit like the ISS. In other words, you can't use Celestia to find out where to look in the sky to see the ISS.
8. I've placed a planet in orbit around a star in a binary system, but I only see light it lit by one of the stars. What's wrong?

   ### Answer:

   It's likely that this is correct behavior. The distance between the planet and the star it orbits is probably much less than the distance from the planet to the second star. If the stars are approximately equal absolute brightness, this means that the light from the closer star will be so much more intense than the light from the more distant star that the secondary illumination will be imperceptible.
   Remember that the brightness of light falls off in proportion to one divided by distance squared. If the second light source is a lot further away than the primary, it must be intrinsically much brighter in order to visibly illuminate a planet.
9. How many simultaneous light sources can Celestia handle?

   ### Answer:

   Up to two in the OpenGL vertex shader paths, and up four in the basic, multitexture, and OpenGL 2.0 paths. The light sources with the greatest apparent brightness are given priority.
10. Ring and eclipse shadows don't look right when there are multiple light sources.

    ### Answer:

    Only the OpenGL 2.0 render path handles shadows correctly when there is more than one light source. In the other render paths, only the shadow from the brightest light source is considered. The OpenGL 2.0 path can render ring shadows and up to three eclipse shadows per light source.
11. The Sun and the Moon are much too small in Celestia. What's wrong?

    ### Answer:

    Their diameters are exactly right. As seen from the earth, they are both about a half-degree across. Celestia's window is about 45 degrees across, so the Sun and Moon are about 1% of that. They are drawn only 10 pixels wide if your screen is 1024x768.
    Remember that your computer screen is only about 10-20 degrees wide in your own field of view. Celestia's 45 degree field provides a "wide angle" view of the sky. This makes objects look smaller than you might expect.
    The apparent large size of the Sun and Moon as we see them in the sky is a psychological illusion. There are several different explanations for this. If you take a picture of the moon with a camera lens that has the same field of view as Celestia, you may be surprised at the small size of its image.
    At least one book has been written about this effect:
    The Mystery of the Moon Illusion: Exploring Size Perception
    By Helen Ross and Cornelis Plug.

## General Questions

1. Where can I get more information about Celestia?

   ### Answer:

   A good start is the documentation on the Celestia Website and the pages on the Celestia Motherlode documentation. For example an introductory User's Guide by Frank Gregorio is available in English. Translations into German, French and a few other languages also are available. Consider providing a translation into another language yourself.
   An other good place to look for or ask for additional information is the Celestia Forum. You'll find lots of friendly people there. Selden Ball's website has pointers to additional documentation on catalog files (SSC, STC, DSC), planet surface textures, etc. Also you can find information in the Celestia WikiBook.
   On the Celestia Motherlode there are also many other Celestia resources and addons for download.
2. Where can I get the most recent version of Celestia?

   ### Answer:

   Get the most recent Celestia installation file from GitHub. Official prerelease versions are announced in the Celestia Web Forum in its Development Forum.
3. What changes have been made to Celestia since the last version?

   ### Answer:

   The developers maintain a list of all new functionality and bug fixes in the Celestia ChangeLog, which is located at GitHub. Look at the top-most entry in the list, to the right of where it says "Revision #.##", click the "(view)" link to display the most recent ChangeLog.
4. I have a previous version of Celestia with tons of addons, custom textures, etc. How can I update to the latest version without having to reinstall all of those addons, textures, etc?

   ### Answer:

   You can have more than one copy of Celestia on your system at the same time.
   - Rename the directory (folder) where you have Celestia now, maybe to Celestia151.
   - Verify that things still work:
     - Double-click on the icon for Celestia151\Celestia.exe and look around in your universe.
   - Install the new copy of Celestia and tell it to use the directory Celestia. It'll create the folder again and install itself there.
   - Move your addons at leisure.
   Cel:// URLs run the copy of Celestia that is in the folder named Celestia. If you want to change back to using your old Celestia that way, just rename the directories again: rename Celestia to be Celestia160 and rename Celestia151 to be Celestia.
   Also, please take a look at https://www.classe.cornell.edu/~seb/celestia/addon-intro.html for a description of how to organize your addons so they can be moved easily.
5. Why don't Windows and Mac addons work under Linux?

   ### Answer:

   Always use only lower case letters and numbers in file names. Use only the underscore [_] as word separators, not spaces. Avoid using composite characters.
   Too often people are careless with filenames when creating addons. The capitalization of names must be consistant for an addon to work under all operating systems.
   My_Addon.dsc is not the same as my_addon.DSC and not the same as my_addon.dsc. They are names for different files.
   Linux and other Unix derived operating systems can tell the difference between upper and lower case. Linux can have three different and separate files with those names.
   If you specify:
   Texture "texture.jpg"
   in the catalog file, then the filename must be texture.jpg in the textures folders. If the file is named Texture.JPG, Celestia won't find it because that's not the file that it's looking for.
6. What is SPICE?

   ### Answer:

   SPICE is a project of the NASA Navigation and Ancillary Information Facility (NAIF). It allows calculations of positions and velocities of planets, satellites, comets, asteroids and spacecraft. It is used by NASA, ESA, JAXA and other space agencies as well as individual space missions. It consists of a "SPICE toolkit" of computer software and "SPICE kernels" or data files. SPICE kernels are available from multiple mission websites as well as the main NAIF website https://naif.jpl.nasa.gov/naif/.
   SPICE data is highly detailed, and will provide improved positional accuracy over the standard Celestia positioning model. It can be incorporated into the *.ssc Celestia data files. There is also a spice2xyzv tool that converts SPICE kernels to a Celestia xyzv format. See the Celestia WikiBooks for information on obtaining and using SPICE data.
   SPICE support is an option when compiling Celestia. To see if your copy of Celestia has SPICE support, click on Help -> About Celestia. If SPICE or NAIF is listed as supported, then SPICE support is present.
7. I have created pictures/videos with Celestia. May I sell them or use them for or in commercial productions?

   ### Answer:

   The answer to that question is twofold.
   1. If the pictures and movies were created by you by using only the official distributed copy of Celestia they are yours to do with as you want. In any case if you are using pictures/videos made with Celestia you have to recite Celestia as the origin.
   2. If you create pictures or movies using Addons, however, then you have to abide by the license of that Addon. Most Addon creators allow their works to be used freely for educational purposes, but forbid commercial use. In any case it is a good idea to contact the creator of the Addon and ask for his permission.

## Windows questions

1. General information
   A lot, if not all problems described are due to the fact that windows doesn't allow data to be placed in the program files directory. That is part of the security system (UAC) and can be turned off completely, or partly.
   To enhance compatibility and still use UAC Microsoft implemented a work-around for programs, by redirecting data into the "compatibility" directory.
   Another way would be to install the complete Celestia program, including its sub-directories anywhere, away from the "Program Files" directory. Some people have reported having fewer problems if they install Celestia somewhere else than in "Program Files".
2. When trying to install the program on my Windows machine the installer says it needs administrator rights which I don't have.
   In earlier versions there was no need for administrator rights. Why does this version require administrator rights, and is this something that can be fixed?

   ### Answer:

   The administrator rights are caused by the installation itself. Celestia wants to retain its own authorities when you install it, and that creates these problems. The only way to fix it is to either reset the permissions which you cannot do unless you have the administrator rights, or you can copy the files to a location that you have created yourself.

   ### Solution:

   Set up a different folder for Celestia and simply copy all the original files to the new folder. That is if you can.
3. Celestia does not start and reports missing dlls.
   What do I do if Celestia fails to start with messages that files MSVCP140.DLL, VCRUNTIME140.DLL and VCRUNTIME140_1.DLL are missing?

   ### Answer:

   These are runtime files of Microsoft Visual C++, the programming language used to compile Celestia. They are not shipped with Windows, although some programs do come with them. You need to add them to your computer.

   ### Solution:

   Microsoft has a download site with a "Visual C++ Redistributable" file in Win64(x64) and Win32(x86) versions. You must select a Visual Studio version of 2015 or later. As the files are backwards compatible, it is best to use the most recent version. Download and run the file to install the needed dlls.
4. Why can't I make changes to files in the Celestia data directory?

   ### Answer:

   The short answer is – when installed with the default options – Celestia takes ownership of the directory, so you simply cannot make any changes to the files in the data directory.
   Well, you can make the changes, it's just that you simply cannot save the changes to the data directory. This problem can be overcome by some work with permissions and security within Windows.
   You cannot change the celestia.cfg file, by the way.

   ### Solution:

   To avoid having to deal with all of these "permissions" issues, Windows users (on a single home PC) can simply copy a SSC file to a different directory.
   Make any changes to the copied version, then copy it back to the C:\Program Files\Celestia\data folder.
   You will be asked if it's okay to allow this copy, and you can respond Yes. Once you have done this you will be able to edit the copied file in the Celestia directory without trouble.
5. What are compatibility directories?

   ### Answer:

   Beginning with Windows Vista, the compatibility directories are created when you try to install Celestia as an application defined as being associated with a previous version of Windows, i.e. XP, 98, etc.

   ### Solution:

   Most of the compatibility directories will not be created if you install Celestia as a native Windows Vista application.
   Running Celestia in the native Vista mode seems to work pretty well. You may find also that you can simply move a compatibility file from its current location (once it has been created) into the standard Vista C:\Program Files\Celestia directory where you wish it to be. Once done, it will usually stay where you put it unless it is again acted upon by a non-Vista program.
   If you also use other programs to perform functions like editing plain text SSC files using previous Windows version compatible programs, these will also cause compatibility directories. So, it is the best to use Vista-ready programs for all of the Celestia-related functions.
6. I can't find/see those compatibility directories. Why?

   ### Answer:

   These files are "hidden" in the normal Vista environment (and in Windows Explorer) if you use the default values of Windows.
   If you want to see these files, or to see if there are any compatibility files in use, here is a short explanation of how to enable the view of "hidden" files in Vista's Explorer.
   With standard installation of Windows your compatibility files should generally be found under the User's Folder. These compatibility files cannot be seen unless the user has the ability (using Windows Explorer) to show the hidden files.
   This is done (in Windows Explorer) by clicking on the "Tools" option on the Explorer Menu, followed by "Folder Options", "View", then clicking on "Show hidden files and folders" and finally clicking on "Apply" in order to show these files and folders.
   After this has been done, you can then look to the previously hidden folder named "AppData" to see if compatibility files are in use for Celestia.
7. Where are the files that I just edited and saved?

   ### Answer:

   On occasion Vista creates copies of your textures or other Celestia files when they were modified. Your new textures may not show up in the Celestia textures directory, but may be transported to an entirely different directory used for compatibility issues.
   Some textures will show up in the compatibility directory, and others will show up where you saved them in the Celestia directory.
   Your texture may be either in: C:\Program Files\Celestia\textures\medres
   OR, it will be in: C:\Users\YourName\AppData\Local\VirtualStore\Program Files\Celestia\textures\medres
   It is possible to go to the compatibility directory, and move or copy the compatibility file directly back to the Celestia directory.
8. How do I use the 3dstocmod converter?

   ### Answer:

   In order to use the 3dstocmod converter in Vista, you have to convert the elements via Vista's "compatibility" mode under the file's "properties" dialog.
   For every .exe and .dll file, you must specify compatibility for Windows XP, and you must specify that "Visual Themes" are to be disabled.
9. What causes Celestia to crash on Windows?

   ### Answer:

   Celestia will crash if you do not have up-to-date graphics drivers. The graphics drivers included with Windows are frequently buggy and not up-to-date. You must download and install updated drivers from the Web site of the manufacturer of your graphics hardware.
   Do NOT use Microsoft offered graphics drivers, since they frequently have not the support for the latest OpenGL features, even if your graphics card is capable of providing them.
10. Do Cel:// URLs work under Windows?

    ### Answer:

    Cel:// URLs work fine under Windows with MS Word.
    MS Word automatically requires the use of [Ctrl] + click to launch a hyperlink, but there is a menu item to eliminate the need to press [Ctrl].
    - Go to the "Tools/Options/Edit" menu, and uncheck the box that says, "Use Ctrl+Click for hyperlinks".
    - Click OK.
    From that point forward, simply pointing and clicking once on a cel:url or hyperlink will launch it.
11. Are there security impacts from Windows on Celestia?

    ### Answer:

    Since Vista, Windows enforces some security requirements which usually are optional under earlier versions of Windows. You may have to select options to disable that enforcement for Celestia. E.g. allowing URLs to run programs.

# Celestia resources

Celestia Web Site: https://celestiaproject.space/
Celestia User Forums: https://celestiaproject.space/forum/
Selden's List of Resources for Celestia: https://www.classe.cornell.edu/~seb/celestia/
Celestia Wikibook: https://en.wikibooks.org/wiki/Celestia
Celestia Motherlode: http://www.celestiamotherlode.net/
Celestia Bug Tracking (GitHub.com): https://github.com/CelestiaProject/Celestia/issues
Celestia Feature Requests (GitHub.com): https://github.com/CelestiaProject/Celestia/issues
Celestia.mobi (Site): https://celestia.mobi/
Celestia.mobi Addons: https://celestia.mobi/resources/categories
Celestia.mobi Addon Submissions (GitHub.com): https://github.com/levinli303/celestia.mobi/issues

# License

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the enclosed GNU General Public License (COPYING) for more details.
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# Contributions

- Authors
  Chris Laurel - claurel@gmail.com
  Clint Weisbrod - cweisbrod@cogeco.ca
  Fridger Schrempp - t00fri@mail.desy.de
  Bob Ippolito - bob@redivi.com
  Christophe Teyssier - chris@teyssier.org
  Hank Ramsey - hramsey@users.sourceforge.net
  Grant Hutchison - grant.celestia@xemaps.com
  Pat Suwalski - pat@suwalski.net
  Toti
  Da Woon Jung - dirkpitt2050@users.sf.net
  Vincent Giangiulio - vince.gian@free.fr
  Andrew Tribick
  Hleb Valoshka
  Levin Li
- Contributors
  Deon Ramsey: original GTK1 interface
  Christopher Andre: Eclipse Finder
  Colin Walters: Endianness fixes
  Peter Chapman: Orbit path rendering changes
  James Holmes
  Harald Schmidt: Lua scripting enhancements, bug fixes
- Documentation
  Frank Gregorio: Celestia User's Guide
  Hitoshi Suzuki: Japanese README translation
  Christophe Teyssier: DocBook and HTML conversion of User's Guide
  Diego Rodriguez: Acrobat conversion of User's Guide
  Don Goyette: CEL Scripting Guide
  Harald Schmidt: Celx/Lua Scripting Guide
  Christian Lenz & Runar Thorvaldsen: New help file
- Scientific Data Base
  Grant Hutchison
  Supplied the correct orientations for the major planets, their moons, and a number of asteroids and also worked on these data files: Solarsys.ssc, nearstars.stc, extrasolar.ssc, extrasolar.stc, earth_locs.ssc
  Fridger Schrempp
  - Complete NGC/IC galaxy database + local group galaxies (galaxies.dsc)
  - Data base on globular clusters (globulars.dsc)
  - Data base on visual and spectroscopic binaries (visualbins.stc, spectbins.stc)
  - World-capitals.ssc
  - Asterisms.dat
  Andrew Tribick
  - Significant update of the star.dat base based on new HIP Reduction of the Raw data, Floor van Leeuwen, 2007
  - CHARM2 stellar radii (charm2.stc).
- Texture maps
  Most of the planet maps are from David Seal's site: http://maps.jpl.nasa.gov/.
  A few of these maps were modified by me, with fictional terrain added to fill in gaps. The model of the Galileo spacecraft is also from David Seal's site (though it was converted from Inventor to 3DS format.)
  The Mars, Neptune, and Uranus textures and Mars bump maps are all from James Hastings-Trew's collection. His maps may be found here: http://gw.marketingden.com/planets/planets.html.
  Grant Hutchison
  - Saturn's rings were built by Grant Hutchison from Cassini imaging, with transparency information derived from stellar transit data obtained from: http://pds-rings.arc.nasa.gov/ringocc/ringocc.html.
  - The Eros map is a shaded relief generated from the NEAR laser rangefinder shape model at: http://pdssbn.astro.umd.edu/NEARdb/nlr/#shape.
  Jens Meyer
  - Dione and Rhea are USGS maps colored and modified by Jens Meyer.
  - The Moon map is based on data from PDS Map-A-Planet at http://pdsmaps.wr.usgs.gov/maps.html with colors from Mark Robinson at http://www.earth.northwestern.edu/research/robinson/MOON/clem_color.html.
  Fridger Schrempp
  - Available data Pluto and Charon textures using maps created by Marc Buie at Lowell Observatory. Buie's maps were generated from photometric data gathered during six years of mutual occultations of Pluto and Charon.
  - Titan's cloud texture in natural colors and its surface map at near-infrared wavelength. They are based on resources available from the imaging site (Ciclops) of the Cassini mission, http://ciclops.lpl.arizona.edu/index.php.
  - The Phoebe base texture was created from the cylindrical map published by the Cassini imaging team, http://photojournal.jpl.nasa.gov/catalog/PIA07775.
  - The Tethys textures are based on the Oct 2008 Ciclops map http://photojournal.jpl.nasa.gov/catalog/PIA11116
  - The Iapetus texture was created from the Oct 2008 Ciclops map http://photojournal.jpl.nasa.gov/catalog/PIA11116.
  - The Lunar topography map, using Clementine laser altimeter data, merged in the polar regions with topographic data from Clementine 750 nm oblique and nadir images, ftp://ftpflag.wr.usgs.gov/dist/pigpen/moon/usgs/topo/global/.
  - The Mercury map was created from a combination of Mariner 10 imaging with recent MESSENGER WAC images from the first two flybys, as collected and reprojected by Steve Albers: See http://laps.noaa.gov/albers/sos/sos.html.
  Phil Stooke
  - Proteus, Janus, Prometheus and Epimetheus maps are from Phil Stooke.
  - The Ida and Gaspra photomosaic maps are by Phil Stooke.
  Various
  - Venus's clouds and the textures for Ganymede, Callisto and Saturn are from Björn Jónsson. His site at http://www.mmedia.is/~bjj/ is an excellent resource for solar system rendering.
  - Venus's surface is a copyright-free NASA image, prepared from Magellan radar data. The original is available at http://www.solarviews.com/cap/venus/venmap.htm.
  - The Earth texture was created by NASA using data from the MODIS instrument aboard the Terra satellite. Further information is available from: http://earthobservatory.nasa.gov/Newsroom/BlueMarble/.
  - The Io and Europa maps are by Steve Albers. His planetary maps are at: http://laps.fsl.noaa.gov/albers/sos/sos.html.
  - The textures for the Uranian satellites were created by Ivan Rivera from JPL data. His Celestia page is: http://bruckner.homelinux.net/celestia.html.
  - The Hyperion and Enceladus maps are photomosaics assembled by Phil Stooke and colored by Jens Meyer.
  - Amalthea is a shaded relief map by Phil Stooke, colored by Wm. Robert Johnston (http://www.johnstonsarchive.net/spaceart/cylmaps.html), and further modified by Jens Meyer and Grant Hutchison.
  - The asteroid.jpg texture was created by Paul Roberts.
  - The textures for the five classes of extrasolar giant planet were created by Andrew Tribick.
  - The map of Enceladus is derived from the December 2008 CICLOPS map: http://ciclops.org/view/5447/Map_of_Enceladus_December_2008
- 3D Models
  - Models of Mars Global Surveyor and Mars Odyssey were created by Shrox: http://www.shrox.com/.
  - The Cassini and Huygens models are by Jack Higgins: http://homepage.eircom.net/~jackcelestia/.
  - The 3D model of ISS is a deconstruction of Andrew Farnaby's complete ISS model with textures by Bob Hundley. The model represents the ISS as of June 2008 and is a modification of the model that can be found here: http://www.celestiamotherlode.net/catalog/show_addon_details.php?addon_id=1199 ISS model of June 2008 (with Kibo) by krisci3 (modified and converted in order to work with JPG by Ulrich Dickmann, a.k.a. Adirondack)
  - 3D asteroid models of Toutatis, Kleopatra, Geographos, 1998 KY26, Bacchus, Castalia and Golevka are courtesy of Scott Hudson, Washington State University. His site is: http://www.eecs.wsu.edu/~hudson/Research/Asteroids/models.html.
  - 3D models of Phobos, Deimos, Amalthea, Janus, Epimetheus, Prometheus, Pandora, Hyperion, Larissa, Proteus, Vesta, Ida, Gaspra and Halley are derived from Phil Stooke's Cartography of Non-Spherical Worlds at: http://publish.uwo.ca/~pjstooke/plancart.htm and optical shape model dataset at: http://pdssbn.astro.umd.edu/SBNast/holdings/EAR-A-5-DDR-STOOKE-SHAPE-MODELS-V1.0.html.
  - The 3D model of Eros was prepared from the NEAR laser rangefinder shape model at: http://pdssbn.astro.umd.edu/NEARdb/nlr/#shape.
  - The Phoebe mesh was designed by Jerry Gardner aka Jestr, jestr@ntlworld.com, based on Phoebe's bumpy topography display from Cassini, http://photojournal.jpl.nasa.gov/catalog/PIA06070.
- Libraries
  - This software is based in part on the work of the Independent JPEG Group.
  - Some versions of Celestia may use the SPICE system for spacecraft and planetary information, developed by Caltech/JPL under contract to NASA.
  - Many cylindrical projections of photographs were performed by Fridger Schrempp with Matthew Arcus mmps software, http://www.users.globalnet.co.uk/~arcus/mmps/.
  - The lower resolution textures were all converted from their higher resolution versions using Gimp.
  - The star database (stars.dat) was derived from the ESA's HIPPARCOS data set.
  - Constellation boundaries are drawn from Davenhall & Leggett's "Catalogue of Constellation Boundary Data": http://cdsweb.u-strasbg.fr/viz-bin/ftp-index?/ftp/cats/VI/49.
- Other work
  - Selden Ball deserves a special mention for suffering more prerelease versions finding more bugs, and giving more feedback than anyone else.
  - Christophe Campos aka ElChristou created the splash screen for Celestia.
  - The MacOS X icon was designed by Chris Alford: http://www.chrisalford.com/.
  - The txf font format used by Celestia was devised by Mark Kilgard.

# Acknowledgements

A very big thank you for creating Celestia goes to Chris Laurel who started this program in the year 2001.
Chris Laurel
claurel@gmail.com
https://celestiaproject.space/.
Special thanks go to all Celestia users who submit bug reports, suggestions, and fixes. Celestia wouldn't be the program it is today, without their help.
The Celestia Development Team