the STEM zone
Things to do with your solar eclipse data
By Dr. Daniel Barth
Activity No. 1
Find the time of first contact (when
the Moon first begins to cover the
Sun) and last contact (when the
eclipse ends). Compare these times
with of ficial data for your area. How
accurate were you?
Build your own
eclipse viewer
It is NEVER safe to view any portion of the Sun
with your naked eye — even during all phases of a
solar eclipse except for the few moments of totality!
To observe the eclipse safely you either need a pair
of safe viewing glasses with solar filters (for one
option, click here), or you need to construct a viewer
that will let you see the eclipse safely
What you need: without looking directly at the Sun. One
way to be properly prepared is to build
• Sturdy plastic
an eclipse viewer from a plastic drinking
drinking cup
cup and a piece of graph paper.
Technically, we will be making a
• Push pin or a
pinhole
camera and projecting the image
brad nail
• Several sheets of the Sun through it onto a piece of
paper. When the Sun shines through a
of copy paper
and a notebook small round hole, it casts a round spot of
light. Many people incorrectly assume
or clipboard
that the spot of light is round because the
• Pencils,
hole is round – this is incorrect! The spot
markers, etc.
of light is round because the Sun itself
is round! You can prove this to yourself
by observing anywhere a tree casts its shadow on flat
pavement or the side of a building. All the spots of
light are round – because the Sun is round! (The gaps
in the leaves are irregular in shape and change as the
leaves move in the breeze.) Take a look at the photo
to the right, which was taken during a partial eclipse
in California. Each spot of light shining through
the leaves shows up as a crescent – an image of the
partially eclipsed Sun!
Let’s build our own eclipse viewer!
Procedure:
1. All that is needed is to push your pin or brad
through the center of the cup’s bottom. A single, small
hole is preferred.
2. Hold the cup so that its bottom points directly
at the Sun and hold your copy paper so that the
projected image of the Sun falls on it. Keep the cup at
a consistent distance from the paper.
3. If you want the image of the Sun to be larger, just
move the cup farther from the paper
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COURTESY OF Daniel Barth
Activity No. 2
Find the time of maximum eclipse
for your area – this will be the sketch
that shows the largest area of the Sun
covered by the Moon. You can project
your image
Math it up!
on fine graph
paper (1-2 mm
The Moon and Sun
squares) to
are both about ½
estimate the
degree wide. Can
percentage of
you determine the
the Sun’s face
average speed
that is covered
of the Moon in
by the Moon.
orbit in terms of
How does
degrees per hour?
this compare
See the solution at
to the official
the bottom of the
estimates for
page!
your area?
Activity No. 3
Use sticky notes or note cards to
make smaller copies of each sketch
that you made. Bind them together
into a flip-book that shows the
progress of the eclipse!
COURTESY OF Daniel Barth
4. As soon as you see the Moon ‘take a bite’ out of
the Sun’s image - trace the image you see as carefully
as you can. Note the exact time on your paper.
5. Make a new image every 10-15 minutes. You will
see the ‘bite’ get larger as the Moon moves to block
more of the Sun from view. Continue this through the
entire eclipse event if you can.
Sky ’ s
Up
What do we learn?
• Although the total eclipse of the
Sun is very brief, the entire solar
eclipse event takes quite a long time –
sometimes several hours.
• The appearance of the Sun changes
as more of it is covered – but we do
not see a change in the light around us
until most of the Sun is covered. This
has to do with the way our eyes and
brain process light.
• When we compare data with
students from across our area, we
will find that the farther someone is
from the path of totality, the smaller
a portion of the Sun’s face will be
covered by the Moon.
o o o
Dr. Daniel Barth left a career as a
research scientist to teach. He has
spent more than 30 years teaching
astronomy, physics and chemistry
at the high school and college level.
A successful science fiction writer,
Barth is the author of Maurice on the
Moon, Doomed Colony of Mars and
other works. He is currently assistant
professor of STEM Education at the
University of Arkansas in Fayetteville,
and author of the Astronomy for
Educators program.
Math it up! Answer: From first contact to last contact, the Moon must move 1 degree. Divide this distance by the
amount of time elapsed between first and last contact.
Sky ’ s
Up
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