# The Pre-Flight Briefing

## Activity 2D: Measuring Elevation

### Student Learning Objectives

This activity is designed to introduce students to measuring elevation, one of the key coordinates used by astronomers. After this activity, students will be able to

• Describe how the elevation of an object is measured.
• Combine compass directions and elevation to find celestial objects.

Summary Students have very little experience with angular measurements. The quadrant provides a simple device with which to measure the elevation of celestial objects, by day or night.

People have observed the sky to help them navigate for thousands of years. Astronomers use the same kinds of angular measurements to find the objects they want to observe.

Ask students to think of a way to safely measure the height of the sun. Remind them never to look directly at the sun.

Materials

• copy on card stock of activity 2D, page 39
• scissors
• 30 centimeters of string
• weight (large washer or nut)
• pencil

Procedure Distribute materials to students. Read instructions together and assist students in construction. Emphasize the dangers of looking directly at the sun. Then show students how to use the quadrant to measure the height of the sun by letting the sun shine through the tube at the top. Once the quadrants have been constructed, plan an all-day measuring activity so students can see how the sun changes elevation during the day.

Suggest that students practice with the tops of flag poles, tall buildings or other easily sighted objects. Two students at the same distance from an object should record the same angular reading. Ask students to work with parents or other adults at home to observe the moon or the bright planet Jupiter in the western evening sky. Both should be easy to find. Students should also be able to observe that these objects change their position (and elevation) during the night.

Interdisciplinary Connection

Use this activity to make a historical connection to Columbus Day, October 12, the day of the first LFS observing flight. Encourage students to investigate how early navigators found their way around the globe. Students can research the navigational methods of Europeans, early Mediterranean civilizations and Pacific Islanders.

KAO Connection

KAO astronomers also have to be careful not to look at the sun with their telescope. Direct sunlight could destroy sensitive detectors. Objects are not observed when they are too close to the sun.

Ask students for a sure-fire way to locate the north star. The elevation of the north star is always equal to your latitude. Instruct students to find their latitude on a globe or map. If they make the angle read by their quadrant equal to their latitude, then look due North through the tube, they should find the North Star!

The time when the sun is highest in the sky is called "local noon". However, local noon rarely falls exactly at 12:00 on the clock. Students can use the quadrant to determine the time for local noon in their location. The variation in local noon is caused by the use of standard time zones. Everyone in the same time zone has 12:00 noon at the same moment. Yet the sun reaches its highest point earlier in the eastern part of a time zone than in the western part. This activity can be extended to a discussion of time and time zones.

### Measuring Elevation

Astronomers describe the location of objects by their elevation or height above the horizon. Construct this quadrant to measure the height of the sun in the daytime and the moon, planets and stars at night.

a Cut out the pattern. Wrap the top around a pencil.

b. Tape it in the shape of tube and remove the pencil.

c. Tie a weight (a nut or washer) to the end of 30 cm of string. Attach the string through the hole at the top of the quadrant.

• Do not ever Look through the tube at the sun.

d. In the daytime, hold the quadrant so that the sun's light goes through the tube and makes a bright circular spot on the ground.

e. Record the angle that the quadrant reads and the time. The quadrant should read 0(deg) when the sun is on the horizon.

f. At night you can look at an object through the tube. The quadrant will then give the object's elevation. Whenever you record an elevation, also record the time.

### Recording Activities

a. Make a table of the sun's height and the time every 30 minutes for a full day and then graph your data. Describe in words how the sun moves during the day.

b. When the sun is highest in the sky, the time is "local noon". Local noon is usually not exactly 12:00 noon. When is local noon in your area?

c. Select a bright object in the eastern night sky and another in the west. Record their elevations for a 2 hour period. How do stars in the east and west move during the night?

KAO Corner:

The Kuiper telescope can be adjusted to observe objects at different elevations. Changing the compass direction of an object requires a change in direction for the airplane.

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