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Moon shadow versus sun reflection

This 5-second video shows a reflected image of the sun – a sun glint – as a bright spot crossing Earth from right to left. It also shows a dark spot – the moon’s shadow – moving the opposite way.

As featured on the Astronomy Picture of the Day at G+ for July 17, 2017, here’s a five-second video made with images from Japan’s Himawari-8 weather satellite. The video shows a full day on Earth as seen from the satellite’s position in geostationary orbit high above the Pacific Ocean. Here’s APOD’s description at G+:

The sun rises to the right and sets to the left, illuminating the half of Earth that is most directly below. A reflected image of the sun — a sun glint — is visible as a bright spot https://earthobservatory.nasa.gov/IOTD/view.php?id=84333 moves from right to left. More unusual, though, is the dark spot that moves from the lower left to upper right That is the shadow of the moon, and it can only appear when the moon goes directly between the Earth and the sun. Last year [March 9, 2016], on the day these images were taken, the most deeply shadowed region experienced a total eclipse of the sun. Next month [August 21, 2017], a similarly dark shadow will sweep right across the USA.

Bottom line: Video from Himawari-8 satellite showing both sun glint and the moon’s shadow on the day of the March 9, 2016 total solar eclipse.

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Deborah Byrd