Download Light Years - Godley ISD

Name: ______________________________ Period: ____ Date: __________________
Lab - Light Year Activity
Instructions:
1. Requires 1-3 students for this activity. Each does own worksheet.
2. Read introduction.
3. Gather required materials and follow procedures.
Materials:
Timing device
2 meter sticks
Introduction:
Distances in space are so large it does not make sense to use a typical unit such as kilometers or
miles. Instead, astronomers use a special unit called a light year to measure distances between
stars and galaxies. A light year is the distance light travels in one year. Moving at 300,000
kilometers in just one second, light obviously covers an enormous distance in one year. Proxima
Centauri is the nearest star to the Earth other than the Sun. Since Proxima Centauri is 4.3 light
years away, it takes 4.3 years for the light from this star to travel the distance needed to reach the
Earth. It is important to remember a light-year is a measure of distance, not of time.
Also, to measure distance within our solar system astronomers use Astronomical Units (AU). It is
the average distance from the Earth to the Sun, approximately 150 million kilometers (93 million
miles). In this activity, you will model the Light Year, a unit of measurement dependent upon both
time and distance.
Procedure:
1. Begin at the starting mark and walk heel-to-toe for 20 seconds.
2. Measure and record the distance in the table.
3. Repeat the procedure for two more trails.
4. Now calculate the average distance for the three trails.
5. Multiply the average times 3 and record your “student minute”.
Trial
#
Average distance in
20 seconds
(meters)
Average x 3 =
Student minute
1
xxxxxx
xxxxxx
2
xxxxxx
xxxxxx
3
Distance in 20 seconds
(meters)
Analysis:
1. During this activity, you were modeling a light year. In the model, what represents the light and
what represents the year?
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2. How is a “student minute” similar to a “light year”?
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3. How is a “student minute” different from a “light year”?
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4. Why do astronomers use light years instead of kilometers to measure distances in the
universe?
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5. If a star located 65 light years away from Earth stops giving off light energy at this very moment,
how long will it be before we can know it? Explain.
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6. When using a telescope to observe stars, some say they are observing the past instead of the
present. What does this mean?
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7. It takes just a little over 8 minutes for the Sun’s light to reach Earth. Why would astronomers
use AU in place of a light year to measure distances within our solar system?
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