Altitude tells you how far an object is above a level horizon. Zero degrees is on that horizon; 90° is directly overhead. Azimuth tells you which way to face, measured from north through east. NightSky also translates azimuth into compass directions such as southeast.
Add the obstacles yourself
The calculated horizon is not the skyline outside your window. A building, tree or mountain can hide an object that has geometrically risen. Visit a new observing spot in daylight, identify safe places to stand, and note which directions are blocked. Do not move toward a dangerous edge simply to gain a lower horizon.
A rough horizon sketch is often enough. Draw the main directions and mark the approximate height of obstructions. Compare that sketch with the altitude table for your chosen observing time. If a target remains low behind a roof, choose another target or wait for it to climb.
Treat compass readings with care
A phone compass can be disturbed by nearby metal and may need calibration. Geographic north, magnetic north and a map's grid direction are not always identical. Use familiar landmarks and a reliable map to confirm a direction before depending on a very narrow opening between buildings.
The small sky diagram is an overhead guide, not a photograph or a telescope field. East appears on its right, and the text table gives the numerical direction. Optics may reverse the view. Read the sampled time beside the diagram: a correct direction at 21:00 can be quite different several hours later.
Sources and review
Reviewed October 22, 2026 by PiSpace Sky editorial. Date-sensitive details can change.