Could eclipse's path of totality be narrowing to cut out more of Michigan? Some disagree

The small sliver of Michigan communities in the path of totality for Monday's rare total solar eclipse could be shrinking based on one new scientific estimate, but some are questioning it.

A new forecast from a solar eclipse blog called Besselian Elements removes more of Luna Pier, Michigan in Monroe County from the path of the total solar eclipse, but two physics experts and the city's mayor are downplaying the forecast.

The Besselian Elements forecast, released earlier this week, differs slightly from maps produced by NASA and other organizations. The path is slightly narrower in the Besselian Elements map, according to one Oakland University professor, which means that most of the city of Luna Pier isn't included in that forecast. Many news outlets have been reporting on the forecast.

A total solar eclipse will cross North America on Monday, including a sliver of Michigan. According to the National Weather Service in Detroit, most of southeast Michigan will experience a partial eclipse, but parts of Erie and Bedford Township, along with Luna Pier, in southeastern Monroe will experience totality between 3:12 and 3:13 p.m.

In communities in the eclipse's path of totality, it will become dark outside, like at dusk. In a total eclipse, the moon passes between the sun and the Earth, fully blocking the face of the sun, according to NASA.

Kapila Castoldi, an adjunct professor in the physics department at Oakland University, said the forecast "isn't a major difference" for the path, but she encouraged people in Michigan to travel at least as far as Toledo to watch the eclipse, just to be safe. Another expert, University of Michigan astrophysicist David Gerdes, said he doesn't have enough information to judge if the blog's calculation is correct.

Meanwhile, Luna Pier Mayor James Gardner said he is skeptical of the new forecast and still trusts NASA's prediction.

The eclipse forecast

The Besselian Elements blog says that one of its team members, John Irwin, has "accurately determined" the position of the path of totality across North America.

"Most notably, this path incorporates adjustments that account for the topographic elevation, both around the limb of the Moon and on the surface of the Earth," the blog says. "It therefore provides a reliable guide for intrepid observers who may wish to venture close to the path limits and witness prolonged, and potentially profound, edge effects around the time of maximum eclipse (weather-permitting)."

Irwin's forecast removes some Luna Pier homes from the path of totality that are in other maps. Only a few homes in the city are included in the path, along with some areas of land that aren't residential. The edge of the National Solar Observatory website's path is further north, almost reaching 10th Street in Luna Pier.

What experts and the mayor say

Gerdes, the UM professor, said that from what he has read, a slight revision to the sun’s diameter might move the outer limit of the path of totality inward by a small amount. He said he doesn't have enough information to determine if Irwin's calculation is correct, but he noted that observers at the very edge of the path only experience a few seconds of totality anyway.

"In any case it’s best to be as close to the centerline to enjoy a longer eclipse and avoid any confusion about exactly where the outer boundary of the path may be," he said. The centerline is a line in the path where totality will be the longest in each state, according to nationaleclipse.com.

Castoldi, the Oakland University professor, said she is a little skeptical because "we are living in a time when ... it's always important to make news" and at times, the news isn't "totally true."

"I trust whoever this is, this expert is, did the recalculation, but why did it have to come out a few days before the eclipse?" she said.

She added that even if it's true, "it's not really a big deal." Castoldi said the total eclipse will only touch "a tiny corner" of Michigan, and she encourages people to travel slightly further south ― at least to Toledo ― to ensure they're in the path of totality.

Gardner, the mayor of Luna Pier, said he knows that city residents won't try to leave Luna Pier and go into Toledo, as there's the chance of traffic issues further into the path. He also said that the "real big factor" is the weather and whether it'll be cloudy on Monday.

"I'm still more concerned about the cloud forecast," he said.