Objective - Use models and graphs that accurately depict scale to compare the size and distance between objects in
the universe.
In a Galaxy Far, Far, Away
(source: UEN)
Materials





Meter stick
Calculators
Map extending 12 miles from our school
Map extending 80 miles from our school
Map extending 600 miles from our school
Procedure
Activity A
In this activity, your group will review Astronomical Units or A.U.'s. You will use a
meter stick as a comparison for the Solar System.
1. Using your Astronomical Unit chart, calculate where each planet in the Solar System
would be on the meter stick. Complete Table I on your worksheet.
Astronomical Unit (AU) Table
One AU = 93,000,000 – the distance of the Earth from the Sun.
Average Distance from the Sun
Planet
(measured in Astronomical Units AU)
Mercury
0.4
Venus
.7
Earth
1
Mars
1.5
Jupiter
5
Saturn
10
Uranus
19
Neptune
30
~1~
Objective - Use models and graphs that accurately depict scale to compare the size and distance between objects in
the universe.
2. Distances in space are so huge, another measuring unit, light-years, is needed to
measure. 3. A light-year is the distance that light travels in one year. Look at the Speed of
Light handout.
3. Use your Planetary Data Sheet. Calculate how long it takes light from the Sun to reach
each planet. Use the following formula(s):
 Distance to planet (miles)  186,000 mps (miles per second) = time it takes for
Sun’s light to reach planet.
o 87,000,000  186,000 = 467.7 seconds (round to one decimal point).
 To get minutes, divide seconds by 60 (467.7 ÷ 60 = 7.8 minutes –
round to one decimal point).
o 785,000,000  186,000 = 4,220.4 seconds = 70.3 minutes. = 1.2 hours
 To get hours, divide minutes by 60 (70.3 ÷ 60 = 1.2 hours – round to
one decimal point).
Planetary Data Sheet
Planet
Distance from Sun (miles)
Mercury
36,000,000
Venus
67,000,000
Earth
93,000,000
Mars
141,000,000
Jupiter
484,000,000
Saturn
887,000,000
Uranus
1,780,000,000
Neptune
2,870,000,000
4. Using the scale: 1” = 2 light-years, twenty-one stars are within twelve light-years of
our Solar System. Seven of them are visible with the unaided eye. Only two of these are
among the brightest stars (Sirius and Procyon). The other stars are red dwarfs and only
visible with a telescope. Of the thirteen brightest stars visible in the Northern
~2~
Objective - Use models and graphs that accurately depict scale to compare the size and distance between objects in
the universe.
Hemisphere, ten of them are within seventy-seven light-years. The other three stars are
from 197 to 522 light-years away.
7. Get your map that extends about 12 miles from your school. Locate Alpha Centauri,
Sirius, and Procyon. (Use the scale 1” = 2 light-years.) Mark the locations on the map
with a different color pencil and identify the star.
8. Get your map that extends about 80 miles from our school. Locate all stars between
and 77 miles on the map. (Use the scale 1” = 15 light-years.)
9. Get your map that extends about 600 miles from our school. Locate all stars greater
than 80 miles on the map. (Use the scale 1” = 100 light-years.)
The Distance to the Thirteen Brightest Stars
Star/Constellation Actual Distance
Scale Distance
1 light-year =1 mile
Alpha Centauri* Centaurus (Southern
Hemisphere)
4.5 light-years
4.5 miles
Sirius - Canis Major
8.6 light-years
8.6 miles
Procyon - Canis
Minor
11 light-years
11 miles
Altair - Aquila
17 light-years
17 miles
Vega – Boötes
25 light-years
25 miles
Fomalhaut – Piscis
Austrinus
25 light-years
25 miles
Pollux – Gemini
34 light-years
34 miles
Arcturus – Boötes
37 light-years
37 miles
Capella – Auriga
42 light-years
42 miles
Aldebaran – Taurus
65 light-years
65 miles
Regulus – Leo
77 light-years
77 miles
~3~
Objective - Use models and graphs that accurately depict scale to compare the size and distance between objects in
the universe.
The Distance to the Thirteen Brightest Stars
Star/Constellation Actual Distance
Scale Distance
1 light-year =1 mile
Antares – Scorpius
197 light-years
197 miles
Spica – Virgo
262 light-years
262 miles
Betelgeuse – Orion
522 light-years
522 miles
*Alpha Centauri is not one of the thirteen brightest stars. It is
included for comparison since it is the next nearest star to our Solar
System
~4~
Objective - Use models and graphs that accurately depict scale to compare the size and distance between objects in
the universe.
Names _____________________________________________________________
___________________________________________________________________
Absent _____________________________________________________________
In a Galaxy Far, Far, Away
Table I - Distance to Planets – Scale = Inches
Relative Distance of Planets: Scale =1 A.U.=1 inch
Mercury Venus
Earth
Mars
Jupiter Saturn Uranus Neptune
Table II - Distance to Planets – Scale = Light-years
Light Time Travel from the Sun
Mercury Venus
Earth
Mars
Jupiter Saturn Uranus Neptune
~5~
Objective - Use models and graphs that accurately depict scale to compare the size and distance between objects in
the universe.
Teacher’s Notes
Instructional Procedures
Invitation to Learn
Show a clip from the movie Star Wars where Han Solo jumps his spaceship The Millennium
Falcon, to light speed (about one hour into the film). Discuss: Is this possible? How long would it
take even if it were possible? And/or
Discuss with students how things might be measured using different scales. Show students that
using some units of measure are not practical.
http://www.cleanvideosearch.com/media/action/yt/watch?videoId=jsNv6c6chBA
Would you measure how long the playground is using millimeters?
 Would you measure how long a book is by how many letters are in it?
 Would you measure how many chocolate chips in a cookie recipe by counting each chocolate
chip?
 Would you say how old you are by using minutes?
Introduce the idea that distance in the universe is measured in light-years. Explain that
distances in space are enormous and that light-years are a more practical scale than using
kilometers or miles.

One nice way to get a local map is to use the Internet site http://maps.yahoo.com to create a
map with your school at the center. The website offers a variety of zoom magnifications. You can
put your school at the center of the map by adjusting the North, South, East, and West
directional arrows.
Answer Activity A – Table I
Relative Distance of Planets: Scale =1 A.U.=1 inch
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto
3/8
inches
3/4
1
1 1/2 5 1/4 9 5/8 19 1/4 30 1/8
inches inches inches inches inches inches inches
~6~
39 1/2
inches
Objective - Use models and graphs that accurately depict scale to compare the size and distance between objects in
the universe.
Answer Activity B – Table II
Light Time Travel from the Sun
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto
3 m 13 s
6m1 8m
s
19 s
12 m 43 m
40 s 16 s
1 h 19 2 h 39 4 h 10 m 5 h 28 m
m 28 s m 50 s 25 s
53 s
~7~
Objective - Use models and graphs that accurately depict scale to compare the size and distance between objects in
the universe.
The Universe in Numbers
The Milky Way is 100,000 light-years across and
2,000 light thick at its center.
Our Sun is 30,000 light-years from the center of
the Milky Way.
There are more than 100,000,000,000
(one hundred billion) galaxies in the universe.
Each galaxy has between 100,000,000,000 and
300,000,000,000 (three hundred billion)
The Andromeda Galaxy is the nearest galaxy to
ours. It is 2,900,000 light-years away and 150,000
light-years across.
The Local Group contains 50 galaxies and is
5,000,000 light-years across.
~8~
Objective - Use models and graphs that accurately depict scale to compare the size and distance between objects in
the universe.
The Speed of Light
186,000 miles per second
300,000 kilometers per second
11,160,000 miles per minute
18,000,000 kilometers per minute
69,600,000 miles per hour
1,080,000,000 kilometers per hour
16,070,400,000 miles per day
25,920,000,000 kilometers per day
112,492,800,000 miles per week
181,440,000,000 kilometers per week
5,865,696,000,000 miles per year
9,460,800,000,000 kilometers per year
~9~