New data from NASA's Lunar Reconnaissance Orbiter is helping NASA plot the path the Great American Total Solar Eclipse will take as it moves over the United States on August 21.
A solar eclipse happens when the moon passes between the sun and the Earth, as you know unless you nodded off in science class a lot back in the day, from the Earth's view of it. The moon is, relatively speaking, a fairly small object, so the path where the total eclipse is visible is very narrow. At any single spot along the eclipse path, the moon will totally eclipse the sun for only a few seconds at most, so having a really good map of exactly where the eclipse is going to be visible is important.
Luckily, NASA is on it. Older maps outlining where eclipses would be visible were often not terribly accurate because the mapmakers assumed that people were all sitting exactly at sea level and that the moon had no craters. This supposition was made before we actually got into orbit and then to the moon to get up-close-and-personal photographs of it. Since then the maps charting out eclipse paths have improved, but they still could use some work.
Enter NASA's new way of approaching creating these maps. NASA visualizer Ernie Wright at the Goddard Space Flight Center in Maryland has come up with an elevation map of the Earth to show true altitude (based on NASA data), and he's used a changing lunar limb profile to map out exactly what parts of the moon will actually be seen from the United States during the big eclipse.
The new workup shows more craggy shapes depending on the elevations of both the Earth — with all that jagged terrain of the Cascades, Rockies and Appalachians, which the moon's shadow will pass over during the solar eclipse — and the moon, with its irregular polygon shape and curved edges.
This more accurate map will really come in handy for those who are so psyched about the solar eclipse that they're planning on traveling to some specific spot to see it. (Sadly, we will not be seeing the full solar eclipse from Texas because we aren't in the total eclipse path, but them's the breaks.) Just imagine having gone across the country to see the eclipse and then finding you missed it by a mile. Perhaps that won't happen with these new and improved total eclipse maps.
The total solar eclipse will pass from Oregon to South Carolina. It's the first time the U.S. has experienced a total solar eclipse since 1918, when the umbra started in Washington state and passed over Denver, Jackson, Mississippi, and Orlando, Florida, before leaving via the Atlantic coast.