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Eclipse from above: Astronauts struggle to catch the perfect photo

The orbit of the International Space Station and the curvature of the Earth combine to complicate the capture of a photograph of a solar eclipse.

Posted Updated
Solar eclipse March 20, 2015
By
Tony Rice

Europe and the North Atlantic were treated to a solar eclipse Friday morning. I jealously watched Facebook updates from friends who made the trip to the Faroe Islands, a tiny archipelago halfway between Iceland and Norway that is about the size of Raleigh inside the Beltline, to experience the total eclipse. While skies were clear to the north on the icy Norwegian islands of Svalbard, the 20,000 visitors to the Faroe Islands weren’t as fortunate. There and in much of Europe, clouds blocked the show.

European Space Agency astronaut Samantha Cristoforetti shared eclipse photos from the International Space Station (ISS). She was able to capture the umbra, or darker portion of the moon’s shadow just as it first touched the Earth’s surface. Previous eclipses have been photographed from Low Earth Orbit (LEO) as well.

The crew of the Mir space station captured an incredible image of the Aug. 11, 1999, total solar eclipse as it passed across Europe and the Middle East. The umbra, where observers could see the sun completely blocked by the moon, is surrounded by the fuzzy penumbra where a partial eclipse was visible.

In March 2006, ISS Astronauts captured images of another total eclipse over the Mediterranean Sea. A nearly round shadow over Cyprus and the coast of Turkey are visible in the image. The shadow nearly fills the frame because the ISS was just 230 miles up. This may seem like a long way away, but it is comparable to the distance from Raleigh to Washington D.C.

So why aren’t there similarly spectacular images of the latest eclipse from the ISS?

A little back of the (really big) envelope math shows that as that umbral shadow first touched the Earth, the ISS was 1,400 miles to the southeast, approaching the coast of Portugal. From that vantage point the shadow was just visible on the horizon. Like the shadow cast very late in the day when the sun is low, the shadow cast by the moon during an eclipse onto high latitudes near the poles is also very elongated, rather than the rounder shadows seen in eclipses closer to the equator.

By the time observers on those northern islands caught the first glimpse of totality about 40 minutes later, the ISS was nearly on the other side of the world between Australia and Antarctica.

The next total solar eclipse will occur March 8. It will be visible from South East Asia through the Pacific. This is well within the orbit of the ISS, but whether the timing works out for a great photograph remains to be seen.

The next total solar eclipse visible from North America is on August 21, 2017. The path of totality first touches North America along the Oregon coast and will pass through extreme western North Carolina before bisecting South Carolina.

Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.

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