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Eclipse moves east thanks to moon

I'm awaiting the Aug. 21 solar eclipse episode. The stories and diagrams I've seen explaining the event all indicate that it'll start on the West Coast and move across the country to the southeast. I'm confused as to why it's starting on the West Coast, when the sun rises in the east and moves west. Plus, the Earth is rotating clockwise, which implies to me it should start in the east. Help?

— Gerry, Medford

No need to toss those diagrams in the days leading up to the big event, Gerry. They're accurate.

The sun indeed rises from east to west, but it takes two for an eclipse to tango, and the moon isn't the best dance partner — being about a step ahead of the sun.

The moon rises in the east and sets in the west — same as the sun — except faster, according to NASA, leading to the 1,075 mph difference that's moving the eclipse east.

According to NASA, the difference is just shy of Mach 1.5.

The Earth rotates to the east at a speed of about 1,037.7 miles per hour at the equator (NASA said 1670 km/hour, but this is America). The moon orbits the Earth in the same direction, but at the rate of 2,112.7 mph (or 3,400 km/hour for those who watch soccer).

Tide-related chaos aside, Aug. 21 on Earth is just "Monday" without the moon.

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