Celestia works best with a three-button wheel-mouse. Very inexpensive ones are available which work well with Linux, Mac and Windows computers.
Left drag: Orient the view.
Right drag: Orbit the selected object.
Wheel: Adjust the distance to your current selection.
Right + Left drag: Adjust your distance to the selection.
Ctrl + Left drag: Adjust your distance to the selection.
Shift + Left drag: Changes your field of view (e.g. => Telescopic view.)
Wheel click: Toggles the field of view between 45 degrees and the previous field of view.
Left - click: Select the object you click on.
Left double click: Center the selection.
Right - click: Brings up the context menu.
H : Select the sun. (Home.)
C : Center on the currently selected object.
G : Go to the currently selected object.
F : Follow the selected object.
Y : Orbit the selected object at a rate synchronized to its rotation.
: : Lock on the selected object.
" : Chase the selected object. (The orientation is based on the selected object's velocity.)
T : Track the currently selected object. (Keep the selected object centered in the view.)
HOME : Move closer to the currently selected object.
* : Look back. Causes the view to shift from objects forward in the direction of motion, to objects rearward.
END : Move farther from the selected object.
ESC : Cancel the currently executing motion or script.
Shift+C : Center/orbit. (Center the selected object without changing the position of the reference object.)
Left : Move (or roll) the camera view left.
Right: Move (or roll) the camera view right.
Up : Move (or pitch) the camera view up.
Down : Move (or pitch) the camera view down.
Shift+ Arrow: Orbit the currently selected object in the direction indicated by the arrow selected.
1-9 : Select any of the planets orbiting our Sun. (2=Venus, 4=Mars, etc.)
ENTER : Select a star or planet by typing its name.
Ctrl+C, or Ctrl+INS : Copy location URL to your clipboard.
F1 : Stop.
F2 : Set velocity to 1 km/s.
F3 : Set velocity to 1,000 km/s.
F4 : Set velocity to speed of light.
F5 : Set velocity to 10x the speed of light.
F6 : Set velocity to 1 AU/s.
F7 : Set velocity to 1 ly/s.
A : Increase velocity.
Z : Decrease velocity.
Q : Reverse direction.
X : Set movement direction toward center of screen.
4 : Yaw left.
6 : Yaw right.
8 : Pitch down.
2 : Pitch up.
7 : Roll left.
9 : Roll right.
5 : Stop rotation.
X axis : Yaw.
Y axis : Pitch.
L trigger : Roll left.
R trigger : Roll right.
Button 1 : Slower.
Button 2 : Faster.