[Toastmasters Project #8: Visual Aids. Objectives: Select appropriate visual aids. Use them correctly and with confidence.]
How many people here have seen a total
eclipse of The Sun? Show of hands please.
Most people have not. It is very rare.
If you stand in one place, such as Tavares Florida, it will take an
average of 200 years for a total eclipse of the sun to pass here.
That's 3 lifetimes.
Mister Toastmaster, ladies and
gentlemen. I want to inform you about your chance to see an
eclipse. It is an experience that has been described as so profound
that you will thereafter describe your life in two phases; the part
of your life before the eclipse and the part after.
On August 21 of this year, less than 5
months from now, the path of a total eclipse will pass within a 5
hour drive away from right here. Here you see a map of the USA
with the path of totality. I'll pass it around so you can see the
details. The line of totality is about 40 miles wide. It begins in
Oregon and ends in Charleston, SC.
This map also shows the probability of
cloud cover. That chance ranges from about 80% near Charleston, to
only 10% in parts of Oregon and Idaho.
Throughout the rest of North America, a
partial solar eclipse will be visible. During a partial eclipse, the
sun becomes crescent shaped, like a crescent moon. This picture
illustrates the physics of the Moon's shadow on the Earth. Totality is visible in the umbra of the Moon's shadow,
partial eclipses are visible in the penumbra of the shadow. As you
can see, the umbra is very small, but the penumbra is big.
I would dearly love to see this
eclipse. My wife and I are still trying to choose our strategy. We
will be in Vermont this summer. We could drive 1000 miles to
Charleston, or 2400 miles to Idaho Falls, trading distance for clear
skys.
But clouds aren't the only obstacle.
People will be coming from all over North America and Europe to see
the eclipse. Hotels, and campgrounds have been booked since 3 years
ago. There are even rumors of 3 year old reservations being
accidentally lost, and new reservations go for 10x the normal price.
It will be a mad house. That argues for a spot in the desert of
Idaho, far from people. We have a tent and a car, and that may be
our best option.
What's fun to see? The big
attraction is that the Sun's corona becomes visible. The sun's
brightness hides the corona here on Earth, and to astronauts in
space, except during a total eclipse.
Also, briefly visible may be the “ring
of fire” on The Moon, as shown in this picture. What you see are
the mountains and valleys on the perimeter of the moon in silhouette.
Mountains block the sun, while valleys let the sunshine through. I
think that's fantastic, to see lunar terrain with just my naked eyes.
Speaking of naked eyes, there are
important safety issues to consider. Special glasses can protect
your eyes.
But a much simpler, safe way is to use
pinholes. I love this picture. It shows the shadow of a man holding
his baseball hat. Sunlight streams through the rivet holes in the
hat and project tiny crescent shaped images on the sidewalk.
If you are supervising children, you
need to figure out a way to prevent them from disobeying and looking
directly at the sun. In that case, I recommend this more elaborate
setup with a box. You just tape a small piece of aluminum foil on
one end, with a pin hole. And tape a piece of white paper on the
other end. Then cut a head hole in the bottom. It gives children
something fun to do and the supervisor can oversee that all heads are
in the boxes.
Here's the point. The chance of a
lifetime;, no the chance of three lifetimes is less than five months
away. I urge you to make your own plans, be they elaborate or
simple, to allow yourself, your family, and your friends to view the
event.
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