A Model to Track the Sun's Apparent Movement
Across the Sky
Scientists say monarch butterflies use the sun as their clock and compass
during migration. They have a mechanism called a "time-compensated
hard to visualize this without a model, so try this activity. You'll
need a sunny day, several trips outside, and a plastic dome. First find
the direction to Mexico from your hometown. Draw an arrow on the dome
to show the direction of flight to Mexico. Then, using the model, record
how the sun appears to sweep across the sky during the day.
think, monarchs know all of this by instinct! So even if you find this
complicated, you’ll appreciate the challenges monarchs face when
using the sun as a clock and compass! )
time you go outside, describe the direction you’d need to fly
south to Mexico, in relation to the position of the sun. This
chart illustrates the “flight instructions” you can imagine
monarchs following at each time of day in order to orient southward:
Instructions (in order to fly SOUTH)
with the sun on my left.
straight toward the sun.
with the sun on my right.
sheet of white paper
- Take all
the materials outside. Find a level surface for the paper. Make sure
the location receives sunlight throughout the day.
- Make an
X in the center of the paper. This X will represent our Earth.
the bowl (our atmosphere) upside down on the paper. Mark an x on the
center of the bottom of the bowl with the overhead marker. Make sure
the X on the paper is lined up under the x in the center of the bowl.
Trace the edge of the bowl onto the paper to make it easier to line
the compass determine North for your location. Mark North on the paper
and on the bowl.
- Each hour,
touch the side of the clear bowl with the tip of the pencil so that
the shadow of the pencil's tip falls on the X on the paper. (You can
put a small 1,2,3 etc. beside each dot so you'll remember the order
in which you made the observations). To get accurate results the bowl
must sit in the same location and be lined up in the same way for each
hourly (and monthly reading).
making four or five marks determine which direction the sun is moving.
Repeat this activity each month to show the changes in the angle of
the sun throughout the year. Use one color overhead marker from Sept
through December and another color from January through June. If this
is done on or about the 20th of each month you will see the
results on the fall and spring equinox and the winter solstice.