The path of totality for the upcoming solar eclipse has shifted once more accurate calculations were made by a solar eclipse expert, meaning that some people expecting to observe the astronomical phenomenon may now have to travel further for the event.
On Monday, April 8, the moon will be positioned so that the entire disc of the sun will be blocked in several states, plunging millions of people into darkness during the early afternoon. The path of totality will start in Mexico and extend across Texas, Oklahoma, Arkansas, Missouri, Illinois, Indiana, Ohio, New York, Pennsylvania, Vermont, New Hampshire and Maine before heading over the North Atlantic.
The spectacle is expected to draw crowds from around the nation as people head to areas in the path of totality to witness the eclipse. Meanwhile, officials across the country have voiced concerns about stretched public safety resources and an “enormous strain” on local hospitals and congested roadways. At least four states have urged residents to stock up on groceries and gas and to fill medical prescriptions in the days leading up to the eclipse, as it is expected that traffic could overwhelm local roads.
Most worries about eclipse visibility within the path of totality were that cloud cover could block the astronomical phenomenon, but now people have something else to worry about: some maps they’ve viewed may not be correct.
Multiple maps depicting the solar eclipse’s path of totality have been published in the months and even years preceding the event, but some of them may now be wrong, Forbes reported. Just a week before the event, eclipse calculations expert John Irwin made calculations that resulted in a slight but significant change to the map. Many locations previously expecting to be within the path of totality are now just outside of it, whereas others that weren’t expecting to be included now are.
For example, McKinney Falls State Park in Austin, Texas, is now expected to be within the path of totality according to the new map, the Austin American-Statesman reported. San Antonio also will experience more darkness, but part of Denton, Texas, will now be outside of the path of totality.
The solar eclipse map changed because the sun’s diameter is unknown, Forbes reported, meaning that eclipse maps can be incorrect.
In Irwin’s new map, the original path of totality is shown, as is the new one. The interactive map reveals that the northern edge of the path is narrowed. The southern edge in Texas has extended, allowing some areas to be included in the path that weren’t before, but it narrowed everywhere else.
“John Irwin’s map tries to represent reality more closely than other maps. The eclipse map did not really change: it is just computed in a more accurate way,” a spokesperson from Besselian Elements, which published the map, told Newsweek. “John Irwin’s eclipse map is computed using a value of the eclipse solar radius slightly larger than the traditional value and it accounts for the topography of both the lunar limb and of Earth. The lunar limb is not smooth but it has a complex profile with mountains and valleys.
“Other eclipse maps use the traditional eclipse solar radius and the eclipse path limits they depict usually do not account for the topography of the lunar limb (they use a smooth lunar limb without mountains or valleys),” the statement added. “Recent experimental determinations support a value slightly larger than the traditional value and John Irwin’s map uses its most likely value.”
Those within the center of the path of totality can expect to still experience the total eclipse. However, those on the northern and southern edges may now only experience a partial eclipse, according to the new map.
However, a spokesperson for NASA told Newsweek that NASA’s eclipse predictions haven’t changed, but said the size of the sun in prediction maps may cause discrepancies.
“By accounting for the topography of both the Moon and the Earth, precise eclipse prediction has brought new attention to a tiny but real uncertainty about the size of the Sun–a value that the SunSketcher citizen science project hopes to refine during the upcoming eclipse,” the statement said. “Calculations that use a slightly larger radius for the size of the Sun yield an eclipse path that is slightly narrower. This difference would only affect cities on the very edge of the path of totality, where blanket predictions are difficult regardless–a few city blocks one way or the other could mean 20, 10, or 0 seconds of totality. Uncertainty in the Earth’s rotation can also affect eclipse predictions on this level. Traveling towards the center of the path of totality–even a mile or two–will quickly increase the length of totality that people can see.”
