Center for Astrophysical Research in Antarctica
Labs from YSI 95 :
Shadow Observations.
April Whitt
CARA Yerkes Summer Institute, August 1995
This is the staff copy of the lab.
Introduction
Using a plastic film canister as a gnomon, students will record
shadows at specified times during the session. They will compare
these with shadows recorded at the same times from different
geographical areas. Students will explain the differences among
the shadow records.
Materials needed
- plastic 35 mm film canister, weighted with sand
- data collection sheet and pencil
- stiff cardboard (slightly larger than paper)
- removable tape
- compass to determine directions
- flat, relatively smooth surface with southern exposure
(sidewalk is good)
- pencil or crayon to mark shadows
- chalk
- a sunny day
Students will assemble apparatus as described in the direction sheet
below. Shadows will be recorded at 9:30, 10:00, 10:30 and 11:00 AM.
Their records will be compared to those of other participants in
other locations on Earth. Using an atlas and globe, students will
determine the positions of each of the other participants, chart the
differences among the shadows and explain them.
Procedure
Tape the worksheet to the cardboard. Write in the name of your
museum or city/state/country in the space labeled "Place where
tracing is made". Write in your latitude and longitude, and
please put the date you're doing the tracings on the sheet
somewhere too. Fill the film canister with sand, put the cap
on tightly, and put the canister in the circle marked on the
paper.
Take the apparatus outside. Find a flat surface like a sidewalk on
which to set up your cardboard and canister. Choose a place where
you can either leave the set-up undisturbed for the whole day, or
where you can put the cardboard and canister in exactly the same
place for each tracing. Determine which direction is north.
The edge of the paper with the film canister on it must line up on
an east/west line, with the canister on the south side of the
paper (for the northern hemisphere, or on the north side if you're
in the southern hemisphere).
At specified times during the day, use a pencil or crayon to trace
the shadow the canister makes on the paper. Tracings made every 30
minutes will make a "fan tail" pattern on the paper. For the CARA
project August 7-10, 1995, we'll use about five
tracing times from 9:30 AM to 11:00 AM.
Each time you trace the shadow, write the time next to it. Make
sure the traced outline is clear and dark. When a day's worth of
tracings is finished, please FAX a copy to Yerkes Observatory for
use in our summer CARA institute. If you'd like us to FAX you
copies of all the shadows we receive from around the world, please
let us know. And thanks for your help!
If possible, I'd like to try a rehearsal on Friday, August 4. Make
the tracings at 9:30. 10:00, 10:30, and 11:00 AM and fax them to
Yerkes. Anyone who can participate in this will be greatly
appreciated!
A blank data sheet is here;
sample filled-out data sheets can be found
here
and here
as part of the YSI 95
on-line.
Important Disclaimers and
Caveats:
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Last modified Thursday, 23-Jul-1998 17:35:41 CDT
http://astro.uchicago.edu/cara/outreach/resources/ysi95/shadows.html
