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How to Determine Altitude in Astronomy

To define the location of an object in the sky, astronomers use two figures. The azimuth defines the angle with relation to the local horizon (the angle you'd see looking down on yourself from above), and the altitude defines the angle of elevation, with 90 degrees being directly above you and 0 degrees resting on the horizon. In order to determine the altitude of an object, use a clinometer, which you can construct from a protractor and a piece of string.

Things You'll Need

Drinking straw
Protractor
Clear tape
12-inch piece string
1/2-inch nut

Instructions

- 1
  Align the drinking straw with the base of the protractor and tape it into place --- be sure not to cover the hole in the base of the protractor with the tape, but use more than one piece of tape so that the straw doesn't wobble.
- 2
  Tie one end of the piece of string to the hole in the base of the protractor, along the line that runs from 0 to 180 degrees. Tie the other end of the string to the 1/2-inch nut so that the string hangs straight down.
- 3
  Hold the protractor upside-down, keeping it perpendicular to the ground so that the string is not leaning to either side. Carefully lift the protractor up, looking through the straw until the object whose altitude you wish to find is perfectly centered.
- 4
  Use your finger to hold the string in place, and record the angle marked on the protractor. Subtract this number from 90 to get the angle of elevation, in degrees.

Astronomy