The Convenient Eclipse (at least for Americans)
Every total solar eclipse has a path defined by the full umbra(shadow) of the moon as it moves across the earth. Depending on the variations in the earth-moon distance, the moon-sun distance and the height of the sun above the horizon at each location on the path, the umbra can be as little as zero miles across and, out side of the polar regions, as much as one or two hundred miles across. The duration of totality changes as the shadow moves, reaching a maximum somewhere near the middle of the path. There is one and only one point on the path of an eclipse that is the point of greatest eclipse(GE). Every eclipse has just one.
I have made much of the fact that the August 21, 2017 eclipse is a rare event for America. I have tried to come up with a way to quantify that, to measure it, give it some basis for comparison. This is what I came up with. I live in Sarasota, Florida. The point of GE for the August 21, 2017 eclipse is near Hopkinsville, Kentucky. Using Google Earth, I measured the straight line distance from my home to the GE is about 730 miles. I can, in fact, drive to Hopkinsville along excellent highway in one, long day.
Above is a map showing the paths of the total (in blue) and annular (red) eclipses for the years 2001-2020. For my purposes, ignore the red and focus on the blue lines. Each one has an asterisk (*) which the marks the point of GE for that eclipse. Using the same method to measure the distance from Sarasota to Hopkinsville, I measured the distance from Sarasota to the GE point for every total eclipse back to 1997. Here are the distances.
Year Distance (in miles)
The average of all those is 6,200 miles (10,300 km), nearly 9 times further from Sarasota than Hopkinsville, KY. My point is that, for Americans, the August 21, 2017 total solar eclipse provides a rare opportunity to see, no, experience one of the grandest events in nature. And it is only a day trip distance for 65 million people. I live further than over 100 million people and I am going to see it. You should to. If you haven’t started making plans, now is the time to start.