No easy feat: Observing a solar eclipse over the Arctic
The international Solar Wind Sherpas team, led by Astronomer Shadia Habbal of the University of Hawaiʻi at Mānoa Institute for Astronomy, braved Arctic weather to successfully observe the total solar eclipse of March 20 from Longyearbyen on the island of Spitsbergen in the Svalbard archipelago east of northern Greenland. Their preliminary results are being presented Thursday, Aoril 30 at the Triennial Earth-Sun Summit in Indianapolis, IN.
It was no easy feat. Ever-changing weather predictions, subfreezing temperatures of –4 degrees F (–20 C) and the danger from polar bears were some of the challenges the team faced, but their years of preparation paid off.
Crystal clear skies
The sky over the snow-covered landscape was crystal clear before, during and after the eclipse, so they were able to capture a beautiful solar corona.
Because the Svalbard archipelago, like the Hawaiian Islands, has microclimates, the team observed at two locations to increase its chances of seeing the eclipse.
With local support, the team was able to set up its equipment inside the old Northern Light Observatory and observe the event through specially designed doors that replaced the old windows, and to use an airport hangar located 10 miles away.
Custom instruments to capture the light
Identical sets of imaging instruments were set up at both locations, with six digital SLR cameras fitted with different focal length lenses, and four astrophotography cameras with special filters to observe the colors of light given off by ionized iron atoms, stripped of 10 and 13 electrons. These highly ionized atoms probe the high temperature outer layers, or corona, of the sun.
In addition, a special instrument, called a dual-channel imaging spectrograph was used at the observatory to measure the motions of these ions in the sun’s corona. At the airport, Institute for Astronomy Astronomer Haosheng Lin used a spectropolarimeter that he designed and constructed to measure the sun’s magnetic fields.
The shadow bands—thin bands of light and dark observed prior to and during the total eclipse—were remarkable as the snow-covered landscape offered ideal conditions for seeing them.
The corona of the eclipsed sun, which was at an altitude of 12 degrees, was shimmering throughout the 2 minutes and 20 seconds of totality, with one large prominence clearly visible to the naked eye.
Taking no chances
To maximize the likelihood of observing the corona during this eclipse, other members of the Solar Wind Sherpas team observed from three other sites: the Faroe Islands, located between Iceland and Norway; a Falcon Dassault flying at 49,000 feet (15,000 m) over the Faroe Islands, and an Irish Air Corps CASA CN235 flying out of Dublin. All were successful except for the group on the Faroe Islands, which was rained out.
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