Sooner or later someone had to ask this. Why is the moonshadow only 70 miles wide? At least this time around it will be that, in totality, as it comes through Wyoming. Each eclipse is different, but one of our biggest in July 1878 was still only 118 miles wide.

The moon is obviously so many more times 70 miles in diameter. Those of us who aren't experts may not have even thought about that, much less asked for an explanation. And many non-experts would have guess that the shadow would only be bigger than the size of the moon, itself. In short, more of us probably would have thought the moon would leave an even wider, rather than thinner, shadow.

The answer would be very simple for us if it did not get so much into how we feel about our place in the universe. One expert is a buddy of mine named Jay, who spends more time at the bar than I do. Jay just loves to explain some of the deeper secrets of science to anyone who cares. Actually, speaking fairly simply he often can make things seem pretty fascinating to just about anyone.

Jay says, "It's simple, but it's just so counter intuitive to the way we think. And by the way, that shadow will cross Wyoming traveling at a speed of 1800 miles per hour." Whoah. That one may be tougher to wrap my head around than the 70 mile width. Jay says, however, "Imagine how big the moon is, and how little time it takes the moon and sun to pass in totality. It's just minutes."

Double Whoah!

Maybe this picture helps.

exploratorium.edu