Exploring the Sun
June 1st, 2009 | by Jennifer Crites | Published in Features, May 2009, Multimedia | 1 Comment
Editor’s note: This is the fourth in a series of articles called Working Conditions, about the unusual environments in which some University of Hawaiʻi faculty conduct their scholarly work.
The clock ticks quickly for the Institute for Astronomy’s Shadia Habbal. In all of 2008 she had just one minute and forty-nine seconds to complete her field experiments.
That’s because Habbal, a University of Hawaiʻi at Mānoa astronomer, conducts her research during the brief span of a total solar eclipse.
She and her team travel to remote parts of the planet to study the sun’s corona—its outer atmosphere, which is only visible on Earth when the moon blocks 100 percent of the sun’s light. For reasons scientists have not yet discovered, the corona is much hotter than the sun’s disk, reaching temperatures of a million-plus degrees.
The intense heat strips elements of their electrons, ionizing them. These ionized elements fly off into space on the solar wind, a phenomenon that affects astronauts, space stations and shuttles, communication satellites and even the earth’s magnetic field.
“Our magnetic field is like an umbrella,” Habbal explains. “It protects us but can get pushed around by a gust of wind, exposing us to rain, or in this case, to energetic particles in the solar wind that zap instrumentation and disrupt communications.”
Total solar eclipses occur every year and a half. Each creates a shadow band barely a few hundred kilometers wide across Earth’s surface. To see the corona, viewers must be within this band.
In 2008 that requirement took Habbal, her team and their 800 pounds of specialized cameras, telescopes and other equipment to China’s Gobi Desert. The sensitive equipment was set up in a tent with a portable AC unit and a large window flap that could be opened for viewing.
“We pitched our sleeping tents on the sand,” says Habbal, “but the cooks pitched their tent on two aluminum bed frames raised above the sand—because they knew there were scorpions.”
Working in diverse locations, Habbal has learned to expect surprises.
In China, a taxi collided with her bus, the team was left without food for 24 hours, and driving rain threatened to sink the scientific undertaking. “The clouds parted just minutes before the eclipse,” she says, relieved, “and conditions were perfect during totality.”
Not so in Mongolia. A snowstorm obliterated any chance of seeing the eclipse. In India, however, the 42-second event was spectacular, says Habbal, “with streamers seemingly shooting out to infinity.”
Habbal flirted with danger in South Africa when three rhinos charged her walking party. “They were like small mountains. I thought that was the end of us,” she exclaims. She’s grateful for the animals’ excellent hearing—just five yards from the group, the rhinos stopped and turned around when the guide tapped on the wooden handle of his rifle.
On the way to the Zambia, Africa, site in 2001, at the end of the rainy season, Habbal’s party drove for eight hours through Kafue National Park on a road filled with deep, muddy potholes. When they reached a checkpoint and opened a window for the guard, a swarm of tsetse flies flew into the jeep.
“It was awful,” says Habbal. “They just stick to you. We had to keep swatting them for miles.”
The eclipse site was on the banks of a river filled with hippos, so guides constructed showers using inverted buckets filled with river water.
“There weren’t enough tarps, so our pit toilets were open on the side facing the savannah. We called it the toilet with a view,” Habbal says, laughing. “We never went there at night because we didn’t know what would be lurking,” she adds.
During the Syria 1999 eclipse at ʻAyn Dīwār, a village at the border with Turkey and Iraq, the temperature reached 120°F on the concrete roof of a government building where Habbal’s team had set up their tents and equipment.
“We couldn’t take a shower during the day because the water was literally boiling,” she says.
In her study of the sun’s elements, Habbal has investigated several spectral lines of iron.
One is FeXI. “It’s existence has been known for some time,” she explains, “but nobody had observed and photographed it because it’s near the end of the visible spectrum—borderline infrared—and the technology wasn’t available.”
Habbal made the first recorded image of FeXI during the 2006 eclipse working from a tent in Libya’s Sahara Desert.
A year earlier, she had scouted the area off-road with a Tuareg guide. “The first night it was bitter cold,” she recalls. “We camped at a beautiful oasis where the palm trees were buried all the way to just below their heads, and the sand was finer than on any beach.”
The next day they passed a changing landscape of dunes, rocky outcrops, and an extinct volcano surrounded by a salt lake, high grass and black sand known as Valley of the Mosquitoes.
When they arrived at a flat, featureless area, the guide said, “This is where you want to be.” Habbal’s GPS coordinates confirmed that they were at the exact spot she had requested, and her guide had not used GPS.
“We were in the middle of nowhere. I don’t know how he found it or the oasis at night with only the jeep’s headlights,” she says in amazement, “but his people were once nomads, and he told me that it’s enough for them to go to a place once and they never forget how to get there.”
At eclipse time, Habbal’s team was transported from Tripoli to the site in Libyan Air Force C-130 planes and helicopters. “Everything we asked for, they delivered,” she says. That included generators, liquid nitrogen, internet and phone lines, water for showers and even an unrequested flock of sheep.
Habbal’s eclipse observations have answered many questions but more remain.
She knows from FeXI and other irons that heavy elements are temporarily trapped in certain regions of the sun’s magnetic field and have trouble escaping with the solar wind.
“They’re not getting enough energy to push them away from the sun,” she says, “so the question is, what’s holding them back?”
Habbal is determined to look for answers no matter where the quest takes her. Each finding, she says, will provide another clue to our understanding of the sun and the solar wind.
Tags: Institute for Astronomy, International Year of Astronomy, May09 issue, UH Manoa, Working Conditions
July 27th, 2009at 8:38 am(#)
Habbal and her team watched the 2009 eclipse from the Enewetak Atoll in the Republic of the Marshall Islands, where temperatures climbed over 100 degrees during the day. They will give a presentation on the expedition at 12:30 p.m. July 29 in the Institute for Astronomy auditorium in Mānoa.
While still in the field, Habbal reported that everyone is happy with the experiments, and though there were a few clouds, most of totality was fully visible from their location. (In much of China, where many people went to watch the eclipse, the view was obscured clouds, drizzle, rain and smog.)
The Lawrence Livermore National Laboratory donated space for the team at its whole-body radiation counting facility, constructed as part of the cleanup of the Marshall Islands. While there, some of the team took a boat to Runit island to view the large concrete cap placed over the soil and waste cleaned up from the islands.
Food and water were brought in to minimize exposure to bio-accumulated radionuclides in local produce and water.