Monday, May 08, 2017

Speech #8, The 2017 Eclipse

[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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