Many solar eclipse maps have a major drawback. Here’s how to make sure you are really on the road of the whole

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The solar eclipse maps show clear lines for the whole road – in a narrow strip, where a common solar eclipse will be seen. But in reality, the edges of the road are blurred, uneven and sometimes wrong hundreds of meters or more. It may not matter if you stand in the middle of the road, where many eclipse chasers go to experience the longest duration of the whole. However, for those who are on the edge of the road, the discrepancies may be the difference between seeing the coron of the sun with the naked eye – one of the most incredible glances of nature – and only a crescent sun witness through solar eclipse glasses.

This can be a major problem for cities whose suburbs will be up to the northern or southern total of 2026. August 12 The entire solar eclipse, such as Madrid, Bilbao, and countless small cities and villages in Spain and Iceland.

Why maps are inaccurate

The reason why those neat solar eclipse map lines are not always in line with reality is that the true size of the sun is still a matter of discussion. Eclipse roads have long been calculated using besselian elements, a set of parameters containing spherical bodies and fixed sunlight. However, these values ​​are outdated.

“The canonical standard sunlight we use for over 100 years in the Eclipse computing is about 696,000 kilometers [432,000 miles] or 959.63 attends seconds, Eclipse Computer Luca Quaglia told June 13 at a solar eclipse conference in Leven, Belgium. This number originally published in 1891 by German astronomer Arthur Auwers. ” But if you use that standard value, you will be turned off, ”said Quaglia.

Related: The gaze of the solar eclipse may be different from the edge of the whole

Quaglia’s work over the last decade over Total Solar Eclipses, as part of the Besselan Elements, shows that the obvious size of the sun is closer to 959.95 arc seconds, plus or minus 0.05. It differs only in 0.3 arc seconds to a less than thousands of degrees. It may look gloomy. However, it changes the edge of the whole road to 2,000 feet (600 meters). This is a small problem with major consequences for communities at the edge of the whole road.

Going to the edge

To check and check the new shape of the sunlight, Quaglia and his colleagues do not delve into the maximum in the middle line through the overall solar eclipse – they go to the country. Keeping the second and third contact-acimirka, when the photographic (visible surface of the sun disappears) and reappears, using the GPS-Fime stamp flash spectrum data from the video, quaglia and colleagues frames that can directly test which radius value corresponds to reality. The key to this is the appearance of Baily’s beads – the last and first drops of sunlight broadcasting through the valleys on the moon – showing the beginning and end of the whole.

“The flash spectra is extremely accurate as they can show you exactly the moment when Baily beads appeared or disappeared,” Dan McGlaun, an eclipse cartographer, told Eclipse maps (like Michael Zeiller), which uses a new 959.95 (Michael Zeiler). “You can use this to calculate what bessel elements would have had at that place to make the beads disappear at the time, including the sunlight. This is trigonometry.”

“The zone of uncertainty”

Quaglia and colleagues collected their data from the point near the road – as projected to use other sunlight measurements in Steponville, Texas, 2024. April 8 Even before the eclipse, Quaglia, working with mathematician John Irwin, has already packed mathematics to give new, more accurate local circumstances. More recently, 2026. August 12 They have created special new Eclipse maps for Spain, which are different from other publicly available maps.

These new maps change the exact line marking the boundaries of the whole road in the edge of the “uncertainty zone”. This is partly because it is not only unclear that the sunlight is not sharp. In reality, the Sun’s photo session – a bright face – has blurred edges that disappear into the chromoshere and coron.

“A photographicra is not a solid object,” said Quaglia. This reflects the bugs of the plus or minus 0.05-arc-sekund in any calculation of the sunlight.

This means that observers in a few hundred meters than the boundaries of any calculated whole can still look at the coron – or not. This “coronality” – the likelihood of looking at the coron of the sun right next to the road – is unpredictable. It is impossible to determine how far the corona of the sun will stop to be visible outside the eclipse.

The form of the moon

The Moon also causes uncertainty. During the complete eclipse of the solar, the path of the whole is expected to be the dark shadow of the moon (Umbra). Traditional maps assume a smooth lunar limb, but valleys and mountains allow sunlight to drain like beads. Using the true Jagged profile, which was revealed in detail by the NASA Moon Intelligence orbiter since 2009, Eclipse time can replace up to 3 miles (5 km).

“We have to pay as accurately as possible for the moon’s complex, uneven form if we want to get the most accurate forecasts of internal contact time,” said Quaglia. Calculations that use a smooth limb of the moon can cause road boundaries that vary up to 3 miles from those calculated using the true limb.

3D eclipse maps

Another problem is that the eclipse maps are flat, but the real land is not when mountains and valleys block or extend visibility. That is why Irwin has launched a new 3D calculation method, which reflects not only the sun’s radius and the lunar topography, but also – unequivocally, the Earth’s terrain. All of this is packed in an algorithm called an improved fast forecast that feeds on new maps and the upcoming Eclipse Countdown smartphone app.

Team Eclipse Map 2026 August 12 Different from others. It has uneven edges and even gaps where the mountainous terrain changes the image. Limit compartments hug mountain ridges, sometimes even jumping over the tops where the shadow cannot reach. Kvaglia said it should face reality “Eclipse chasers,” said no map line, can guarantee what you will see.

“We believe that this is the most accurate contact time you can calculate these days, including all vectors that do not include some other forecasts,” he said.

A variable star and a change of land rotation

The accuracy of astronomy is everything, but when it comes to the sun, it will always be a bit rude. The sun is a variable star. Its magnetic activity wax and decreases in the 11 -year sun cycle, and the effect of sunlight is believed to be tens of Milliarc seconds.

“That’s why it would be great if this experiment was done in future eclipses, perhaps throughout the sun’s cycle,” said Quaglia. “That would be the only way to see any variability.”

Another issue of Eclipse cartographers is Delta T. Even if the exact position, width and shape of the moon shadow is known, exactly where it strikes the earth, depends not only on its terrain, but also on how quickly it rotates.

Related stories

—How to read and understand the map of the solar eclipse

– Where can I see a common solar eclipse in 2026. August 12?

– where will be seen in 2027. Total solar eclipse on August 2?

“Earth rotation can change, even if the shadow is the same,” McGlaun said. “Even a tenth seconds can change where the shadow reaches on Earth.” Although the Earth’s rotation speed is known to change with milliseconds, we do not know what it is until it is measured on the atomic watches of the international Group rotation and reference systems in Paris.

Mathematics is complex, unclear and developing. For all those living near the boundaries of the road through the complete solar eclipse, the message is simple: the head behind a mile or two in the direction of the middle line, and the glorious moment of the whole is guaranteed to clear the sky.