If you have an iPhone/iPad with a compass, SkySafari can show you the sky in same the direction that you're holding your phone. As you move the phone around, the view on the sky chart follows your motion. You can identify stars and planets by holding your phone up next to them, and you can find any object in the sky by following an arrow that points in its direction.
You can activate the compass in two ways:
Tap the Compass icon in the toolbar.
Shake your device - one quick shake will do it!
Tap the Compass button again, shake the phone again, or touch any part of the sky chart, to turn the compass off. You can enable or disable the "shake to use" compass/altimeter feature in the Settings > Field screen in SkySafari (or the Settings > Coordinates view in SkySafari Plus and Pro.) You can turn off "Shake to Use" if you find that you're accidentally activating the compass/altimeter too often, or if you prefer to activate them from the main toolbar.
Please note: you need an iPhone 3GS, iPhone 4, or iPad to use the compass; earlier devices do not have one. The toolbar icon for the Compass will not appear if you're running SkySafari on a device that lacks one. If your device has both a compass and a gyroscope, you can't use them both at the same time: if you turn on the compass, the gyroscope turns off, and vice-versa.
SkySafari uses the compass and altimeter to center the sky chart on the direction you're holding your phone. You can also use them to find objects in the sky. To do this, first turn on the compass/altimeter. Then use the Search view to select the object you are looking for. When the Object Info view appears, tap the Center button at the bottom of view. An arrow appears, leading you toward the selected object. Follow the arrow with your phone to center the object in the field of view. When the object is centered, the arrow disappears, and your phone will be pointing toward the object's position in the sky.
Please Note: for best results with the compass, turn your phone sideways to landscape mode. In SkySafari Plus and Pro, the compass and altimeter will be turned off if you connect to a telescope, or lock on the telescope's position in the sky chart. The sky chart cannot be centered on the telescope's position, and centered on the coordinates reported by the compass/altimeter, at the same time.
A note on accuracy: the solid-state compass built into the iPhone/iPad is not very accurate, and easily affected by interference. It can easily be wrong by ten degrees or more. The compass may be useful for locating bright objects in a general part of the sky, but it's certainly not accurate enough to point a telescope - and definitely not a substitute for the Celestron SkyScout.