Compass & Gyro
If you have an iOS or Android device 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.
Please note: some devices, like the iPod Touch and Kindle Fire, have a gyroscope but no compass. The toolbar icon for Compass will say Gyro instead.
You can activate the compass (or gyro) as follows:
- Tilt your device upward.
- Tap the Compass icon in the toolbar.
- On a device with gyro but no compass, tap the Gyro button in the toolbar to activate the gyro.
Tap the Compass (or Gyro) button again, or touch any part of the sky chart, to turn the compass (or gyroscope) off. You can enable or disable the "tilt up to use" compass feature in the Settings > Appearance screen. You can turn off "Tilt to Use" if you find that you're accidentally activating the compass too often, or if you prefer to activate it from the main toolbar.
Please note: in SkySafari Plus and Pro, the compass and gyroscope cannot be used when you are orbiting another object in the solar system. You can only use the compass when you are viewing from Earth. See the Orbit button Help for more information.
Using the Compass
SkySafari uses the compass to center the sky chart on the direction you're holding your phone. You can also use it to find objects in the sky. To do this, first turn on the compass. Then tap Search, and enter the name of the object you're looking for. When the Object Info view appears, tap the Locate button at the bottom of view. An arrow appears, leading you toward your selected object. Follow the arrow with your phone to center the object on the screen. When the object is centered, the arrow disappears, and your phone will be pointing toward the object's position in the sky.
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, at the same time.
A note on accuracy: the solid-state compass built into most mobile devices 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.
Using the Gyro
Unlike the compass/accelerometer, the gyroscope measures your device's orientation relative to a known starting point. The gyro does not measure your device's true orientation relative to north/south/east/west or up/down in the sky. So to find your way around the sky with the gyroscope, you'll need to use a slightly different process.
First, locate a known reference object in the sky, like the Moon. Then search for the same object in SkySafari, and center it on the screen. With the object centered, hold your device toward the object in the sky. Then tap the gyro button (with a finger in your other hand!) to turn on the gyro. Now, as you move your device around, the gyroscope follows its orientation relative to the object you used as a starting point. As you move the device around, the sky chart on the screen follows to match the view in the sky behind it.
As with the compass, you can use the gyroscope to find an object in the sky. Start with a known object in the sky, then find and center the same known object in SkySafari's sky chart, and turn on the gyroscope - just as described above. Then search for the unknown object you're trying to find in SkySafari. When the Object Info view appears for that object, tap the Center button. SkySafari show an arrow that leads toward the object; follow the arrow with your phone to find the object in the sky.