PART 1: Star census collaboration; please join in


                                 SEEING STARS

Activity 1E: "Twinkle, Twinkle, Little Star"

To encourage students to observe the quality of the night sky and to
determine the number of stars that can be seen from their local area.

Ask students how many stars there are outside at night. Accept all
estimates and record them on the chalkboard. Ask how they could go
beyond guesses and estimates. Tell students that they are going to
devise a way to count the stars in the sky. If you have access, tell
them their data will become part of a national, on-line collaboration.

Ask students to explain the phrase "Twinkle, Twinkle, Little Star".
Ask them what "twinkling" means. Explain to students that only stars
twinkle--the moon and planets do not. As a group, make the predictions
as suggested on the activity sheet (SEE BELOW). Pick a time for students to
make night-time observations of stars. 

     * copy of activity1E, page 23
     * empty paper towel or toilet paper tube (must be 3 times longer
       than the distance across the opening!)
     * scissors
     * ruler
     * a protractor (see Activity 2D)
     * a compass (to determine North, etc.)

Plan a time for students to take a "Star Census". Review with students
how to do the counting. If possible, it would be interesting to have
students make these observations in different locations (near a city
or out in the country) and at different times (when there's a bright
moon and when there's no moon). For younger students, you can use
fewer observations. Just remember that each observation represents
1/144th of the sky. If students make only 6 observations, they would
multiply the total number of stars observed by 24 (which is 144
divided by 6).

Have your students try this experiment (at night at the agreed upon time)
to measure the number of stars you can see.  (This is from the teachers
guide, page 23).

1. Make an "Observing Device" from a bathroom tissue or paper towel
   tube. Measure the diameter of your tube. Cut its length to be three
   times its diameter. Through the tube, you will see only a small
   portion of the sky. It would take 144 tubes to cover the whole sky.

2. One by one, face in each of the 4 compass directions (North, South,
   East and West).

3. Hold the tube 3/4 of the way up from the horizon in each direction
   and count the number of stars seen through the tube. Hold the tube
   half-way up from the horizon and repeat the count. Repeat the
   procedure again with the tube pointed a third of the way up. Repeat
   observations for the other directions. 
   (To determine 3/4, 1/2 and 1/3, students can either use a protractor or
   they can simply estimate the angle)

4. Add up the number of stars for all 12 sightings. If it takes 144
   tubes to cover the sky, then you have observed 1/12th of the sky.
   Multiply your sub-total by 12 to estimate the total number of stars in
   the sky. Estimated total number of stars: (includes the stars above
   and below the horizon)

5. Add up and compare the three measurements in each direction. Why do
   you see more stars in certain directions?

Remind students that they need to take RANDOM samples. That means that
they need to use the samples where they see no stars at all, not drop that
sample in favor of one where they see stars. In urban situations, kids are
likely to have "blank" samples. That's what light pollution does to our skies.
If urban kids sample UNTIL they have 12 samples with stars, then they are
going to have false high readings.

Also, KAO Telescope Tracker Allan Meyer notes:
If you're going to do the star counting through the paper tube experiment,
the results over the next week will be lower than average.  This is due to
the full harvest moon which rises at sunset and which will scatter
moonlight quite high in the air.  This will noticeably reduce the number of
stars anyone can see.

There are two parts to the online connection
1) a quick look at some simple data
2) a more detailed, longer time frame collaboration

Part 1:
For the quick look part, have students count the number of stars they see as
detailed above. As a class, come up with one number which is a good
average of the count in your area.  (Don't forget to multiply by 12 to
estimate the total number of stars in the whole sky). Send this one number,
along with your city, state (and country if not US), latitude and longitude to
us. We'll be featuring star-counting and light pollution activities during
the Night Flight to the Stars program, which airs live beginning at 20:00
Eastern on October 13th. So we would like to include your data. Please send
the information above to marc@quest.arc.nasa.gov; in order to be ready for
the evening program, we will need to have the data by 10:00AM Pacific time
on Friday, October 13 (earlier would be better).

Part 2:
We hope that teachers will work with their students to prepare reports
from their observations which better reflect the complexities of the task.
For example, how do the following factors effect the numbers:
 - weather
 - proximity to surface lighting
 - time of night that the observations were made
 - size of the moon (if you take make observations over time)
 - etc, etc

Hopefully the class can together produce a report that includes the original
data and the conclusions that were derived from analyzing this data.
We would like to place these reports on the Internet for other classes to
see and learn from. 

As an additional activity, classes can examine the other reports and
1) get ideas for improving their original report
2) derive new meaning as more data from other locations becomes available
(for example, students may learn that students in the mountains see more
stars then those closer to sea level).

We encourage classes to produce a final report that synthesizes the
information from other reports into a final summary.  These reports will
also be shared online.

The format of these reports is up to the individual teachers. Graphs and
other visuals would make reports more attractive to others, if your class
can find something meaningful to graph. Charts of the real data collected
might be interesting to some. Be as creative as you can, since your
audience will be other engaged classrooms across the county and the world.
For those of you who are Web publishers, please feel free to develop your
information on the Web.  Send these reports electronically if possible to
marc@quest.arc.nasa.gov.  If you are not able to send formatted reports
online, then please mail disks to Marc Siegel, NASA Ames Research Center,
Mailstop T-28H, Moffett Field, CA 94035.  (Any disks sent will be returned).
If sending the reports on disk is a problem, then send in a paper version and
we will scan it in.

When preparing reports, please include enough information so that others
can use your conclusions in their work.  Examples of this type of
information include location, altitude, description of surroundings (bright
city, dark rural area, in-between suburbs), moon phase, etc.

The time frame for this Star Census project is:
  October 13 - quick look data due by 10:00AM Pacific
  October 24 - first reports are due
  November 7 - final summary reports are due



Have you ever wondered what makes a star twinkle? On the next clear
night look at a bright star.
     * How many blinks does it make in 10 seconds?
     * Look at the moon, an airplane or a bright planet at night. 
       Do these objects twinkle?

A star is a point of light. It is so far away that even the largest
telescope cannot show the star's disk. The atmosphere changing between
the star and your eye causes starlight to twinkle.

Make these predictions about twinkling:

a. Do stars lower in the sky or higher, twinkle more?

b. Do stars twinkle more on a windy night, or a still night?

c. Do stars twinkle more at sea level or on a mountain top?

d. Do stars also change color as they twinkle?

Hint: Count star blink rates to answer the first question.

Share your data with students in other locations to answer the
remaining questions.

"Seeing" is the term astronomers use to describe the steadiness of
images. "Seeing" is best when the twinkling is least. When the seeing
is good, astronomers can collect better data about the brightness and
color of distant stars and galaxies.
     * Estimate how many stars you can see at night?
     * Do you see more stars in the city, or out in the country?
     * Do you see more stars on a moonless night or when there's a full

The KAO flies above most of the earth's atmosphere, higher than most
water vapor and clouds. At 41,000 feet, the stars do not twinkle. The
sky is much clearer and more steady above most of the atmosphere.

Many poets have written about the night sky. Encourage students to do
a literature search for poems about starry nights. As an alternative,
after completing Live From the Stratosphere, you could have them
rewrite "Twinkle, Twinkle..." in "Scientifically Correct" language,
applying as many of the new concepts they've acquired in an
intentionally light-hearted parody of the old nursery rhyme.
"Scintillate, scintillate, giant Globe of Gas..." might give them the
idea, but we're sure your students can do better than the LFS
Development Team! You'll find literary sidebars throughout this Guide,
and can share them with your students. You can see poet Gerard Manley
Hopkins playing with words to match his perceptions of the stars.
Encourage your students to do likewise, and share their work with the
LFS project, via mail or e-mail, when you return the Teacher and
Student Evaluation forms.

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