Sonoma Valley High teacher educates on the eclipse

Dean Knight is worried you are going to damage your eyesight on Monday|

Dean Knight is worried about you. Worried that you will look directly at the sun next Monday during the solar eclipse and damage your eyes.

It’s called “solar retinopathy,” permanent damage to the retina in the back of the eye, and it is the reason people instinctively turn their heads when confronted with a bright light.

Knight is in year 46 of teaching chemistry and AP physics at Sonoma Valley High School and he was so worried that he gave a spontaneous demonstration to all the district teachers during the recent Welcome Back Teachers event at the high school.

“I felt uncomfortable doing it,” said Knight. “But I talked with Will (Deets, principal of Altimira Middle School and emcee of the Welcome Back event) over donuts and I told him I want to teach people how to see the eclipse safely.”

Added Knight: “He said he could give me five minutes; I said I only needed one.”

Thus a packed house of educators learned that they could project the eclipse on any wall using a mirror, some tape, a ball and a cup.

“It is a version of a pin-hole camera, but it reflects light rather than passing light through a small opening,” said Knight. “What is different is that I taped the mirror to a ball and set the ball on a can that rests on the ground, so by just rotating the ball I could have the reflection in any direction that I wanted.”

It’s a similar mount to that used by Isaac Newton with his reflecting telescope.

“The image is the shape of the object that is producing the light,” said Knight.

Knight was explaining this outside of his classroom when he noticed a second image on the wall. It was the face of a watch reflecting the sun onto the wall exactly like the mirror does. One can also put a hole in a piece of thick paper and look at the shadow of the sun reflected on the ground.

Or you can get ISO certified solar viewing glasses.

Or you can go to the Ferguson Observatory in Sugarloaf on Monday and look through a filtered telescope.

Just never look at the sun directly.

The eclipse is a quirk of cosmic geometry. The shadow is caused by the moon blocking out the sun because of the convergence of their elliptical orbits. Even though the moon is 400 times smaller than the sun, the sun is 400 times further away. The path of totality (where the moon is completely blocking the sun) will travel across the US at about 1,500 miles an hour from Oregon to South Carolina beginning Monday at 10:19 a.m. and ending at 2:44 p.m.

In Sonoma, we will be able to see a partial eclipse from 9 to 11:30 a.m. with peak coverage of about 80 percent at 10:15 a.m. This is a big deal for scientists and comes at a time when science could use a little attention.

“For me, looking at the eclipse is great but I am more interested in teaching the theories around it,” said Knight. “You can figure out diameters of planets and distances and angles, and speed of rotation, all from watching the movement of a circle on the wall.”

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