| MAKING
A YEAR-CLOCK
Push a long
nail, point up, through the center of a 1 foot
square of heavy cardboard. Place the cardboard on a sunny
windowsill and do not move it again until this whole experiment has been
completed. Mark a dot at the tip of the nail's shadow every day at the
same time for several weeks.
You will
realize that the shadow movement is related to
changes in the sun's position, and find that the sun does not travel in
the same path each day. Determine what features change or stay the same
from day to day.
Compare the
shadow curves for widely different times of the
year (e.g., September, January, May) or exchange similarly
obtained information with a school further to the south or
north. This activity can also be done using the shadow of a flag-pole,
a telephone pole, or a tall tree.
You can also
do this: Make a pinhole in a piece of black
construction paper and fasten the paper to a sunny window.
When the rest of the room is darkened, the light from the sun will shine
clearly through the hole. Stand a piece of white cardboard about 3 feet
from the window so that the sun makes a small bright spot on it. (This
spot is an image of the sun.)
Mark the
location of the spot with a pencil and watch it for several minutes. Extrapolate
("ex-TRAP-oh-late": infer or estimate by extending or projecting
known information) what path the sun's image would make on the paper from
sunrise to sunset.
Does this
make any sense when you think about the "midnight
sun" at the North Pole? (Probably South Pole, too.) I knew a person
who had lived in Fairbanks, Alaska. She commented about the sun being
always up or always down. Said it was really weird to work all "day,"
go to bed in daylight, get up in the morning and the sky looked the same
as it had when she went to bed the night before. She also said it was
really weird to do all that in the dark. It took a couple of years to
get her internal clock to function properly.
This brilliant
writer made up the term, "Year-Clock." I do
not know whether or not is a valid term.
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