Umbra and Penumbra

More detail on how the Moon’s shadow will sweep over the Earth on March 20. The picture, from Astronomical Calendar 2015, shows the situation at 9:30 Universal (Greenwich) Time. The gray tapering cone represents the umbra or total shadow (not really visible when out in space). The small dark ellipse is the umbra’s footprint on Earth’s surface at this moment; for people within it, the Sun is totally covered. The huge penumbra, or partial shadow, becomes gradually less dense toward its outer edge, as more of the Sun is visible. Curves show this penumbra’s limit at times before and after.

150320eclipseGlobeA

Here is a closer view at the same time. Totality will reach the Faroe Islands (emphasized in white) at 9:41 and last about 2 minutes.

150320eclipseGlobeB

During those precious seconds (if the low Sun isn’t behind fog or cloud) we’ll whip our protective goggles away from our eyes and revel in the sight of the eerie and glorious corona exploding from behind the black circle of the Moon.

The Faroese joke is that their dry season is February, because in that month it can rain for only twenty-eight days.

Nevertheless, we sail in hope.

 

 

 

2 thoughts on “Umbra and Penumbra”

  1. We hope you were able to see the eclipse Guy! According to pictures posted on spaceweather.com this morning, it was totally clear in Svalbard. With luck, you experienced the same thing on your expedition. Here in the United States, we are holding out for 2017. I traveled to Germany in 1999 with my parents and other family members to observe that eclipse but we were clouded out. Here’s hoping that its Saros successor in 2017 will reveal itself in the eastern US.

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