Viewing the Solar Eclipse in Door County

This illustration depicts a rare alignment of the sun and moon casting a shadow on earth. NASA illustration.

by Gary Henkelmann and John J. Beck

You’ve probably heard about the upcoming solar eclipse by now. Even the post office is selling stamps with special thermal ink that turns the black disk of the sun into the full moon just by touching it. There is a lot of excitement out there.

So what’s the big deal?

It has been 35 years since a total solar eclipse crossed the contiguous United States, and this eclipse will only cross the United States, so it’s ours alone. The path of totality, a narrow band about 70 miles wide, will only be visible for less than three minutes on the ground as the moon’s shadow races across the country at speeds between 1,450 and 2,400 MPH. This “umbral” shadow will be ashore during a 90-minute period, while the entire North American continent will be able to observe a partial eclipse by the moon’s shadow several hours during the middle of the day.

Being immersed in a total solar eclipse is an experience those who have seen one will never forget. People are expected to flock to the eclipse path to witness this amazing spectacle, where the sky turns black, the stars and planets reappear, the sun’s corona can be observed with the unaided eye, birds stop singing, cows head for the barn, the air cools and the wind dies. It’s eerie, and a good reason for taking a road trip.

The eclipse path will cross the U.S. from Oregon to South Carolina. The areas away from the central path will have only a portion of the sun’s disk obscured.

How often do total solar eclipses occur? On the average, one happens about once every 18 months. After this year’s Aug. 21 eclipse, the next total eclipse will cross Chile and Argentina on July 2, 2019, and again farther south in those two countries on Dec. 4, 2020. Thereafter, Antarctica’s penguins will be treated to a Dec. 4, 2021, blackout, and on April 20, 2023, Indonesia gets the prize. You can see that most of the planet is not treated to an eclipse very often. The calculated frequency of any particular place on Earth experiencing a total solar eclipse is about once in 375 years.

No wonder, then, that U.S. towns along the eclipse path are bracing for huge influxes of tourists, fanned by articles like Space.com’s “Solar Eclipse Day Craziness Could Resemble a Zombie Apocalypse.” Traffic jams, fuel shortages, inadequate food supplies and overwhelming demand for comfort facilities are being prognosticated as frantic travelers seek out cloud-free skies to witness this ephemeral event.

Sun watchers gather around telescopes fitted with white light solar filters. Photo by NASA Kepler Mission.

The reality may not live up to the hype, though; such ominous predictions are in the genre of today’s weather forecasts that dwell on worst-case scenarios for the shock value. What will happen is, wherever one is at the moment the sun disappears there will be dramatic changes to the local environment that will never be forgotten. Then, about two and a half minutes later, it will all be over.

Statistically, the “best” place for viewing the eclipse is in the western states of Oregon, Idaho, Wyoming and Nebraska where the odds of having clear skies can approach 90 percent. Closer to home in the Midwest, we have about a 50 percent chance of being cloud-free, so pre-determining a viewing site may not prove successful. Keeping one’s options open and being mobile are good tools to a higher success outcome. True, this strategy implies some risk of encountering congestion, but by allowing enough time to reach a clear area, and by being prepared to accept slight deviations from an “ideal” location, there should be enough clear sky available for everyone.

Locally, possibly the best place to observe the Great American Eclipse is at the Leif Everson Observatory and Stonecipher Astronomy Center (2200 Utah St.) on the grounds of the Crossroads at Big Creek in Sturgeon Bay. Take Utah Street east from Hwy 42/57 up to the stop sign and turn left onto Stargazer Way. If the sky is clear the observatory will stream video of the partial eclipse both on the observatory monitors, and in the Astronomy Center through projection from nightskiesnetwork.ca onto the screen inside the darkened classroom.

Using a projection method to view the sun. Photo by NASA Jet Propulsion Laboratory.

Members of the Door Peninsula Astronomical Society (DPAS) will offer safe views of the eclipse through their telescopes and answer questions anyone may have. In addition, live images of the total eclipse from across the country will be streamed for all to see, even if it’s cloudy in Door County. There will be plenty of safe-viewing glasses distributed for those who would like to gaze at the eclipse as it progresses.

The eclipse begins at about 11:56 am and will peak at 1:16 pm. Locally, the maximum magnitude of 0.82 (diametrical coverage) and obscuration of 77 percent will occur at that time.

There’s more to a solar eclipse event than just watching a shadow cover or partially cover the sun. Some people have noticed, when the sun is about half blocked, the sunlight coming through a densely foliaged tree will be focused, by the tiny openings among the leaves, into multiple images of the partially covered sun projected onto the ground. Electric companies have to plan not just for the brief loss of solar electricity but more so for the power surge when acres of solar panels come back onto the grid. Amateur and professional astronomers will take precise measurements of the times when each phase of the eclipse takes place. The solar eclipse provides a unique opportunity for obtaining important scientific data.

This map shows the globe view of  the path of totality for the Aug. 21 total solar eclipse. Image by NASA’s Scientific Visualization Studio

NASA will broadcast live at nasa.gov/nasatv. In addition to the NASA TV broadcast, live video streams from locations across the country will be available at nasa.gov/eclipselive.