Solar eclipse: chasing the shadow

By Joe Cali November 12, 2012
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Chasing solar eclipses can be seriously habit-forming. Here’s a guide to catching a glimpse of this phenomenon.

ON 4 DECEMBER 2002, a solar eclipse crossed over the Atlantic, 2000km north-west of Angola, Africa. Three hours later, the eclipse’s shadow had travelled half-way around the world to the Australian southern coast at Ceduna, SA. Within minutes it would race across an 800km long and 30km wide sliver of outback Australia between Ceduna and Cameron Corner. An estimated 40,000 eclipse chasers gathered along beaches and highways, in streets and parks, at camping grounds, car parks and sportsgrounds, in small towns and on outback properties.

Such an influx of people was a once-in-a-lifetime event for the remote Cameron Corner community. Prior to the eclipse, I spoke to the owner of the local garage-cum-general store, Bill Mitchell. “The eclipse scared me at first,” Bill told me as he filled my tank. “Not the eclipse itself, just the number of people who were heading out this way.” As I waited at our observation site on Lindon station, near Cameron Corner, I remembered my first encounter with the ‘shadow’ in Bolivia eight years earlier.

We arrived at Lake Poopo on the barren landscape of Bolivia’s Altiplano – a spectacular, 1000km long series of plateaus in the Andes – two hours before dawn on 3 November 1994. At 3700m, the air was icy and thin. Bands of fine cloud wandered across the sky, occasionally obscuring the Sun.

“Contact!” someone shouted. The Moon’s disc began sliding across the Sun. The temperature dropped and a raw wind rose. A dark blue shadow appeared in the western sky and soon consumed the Sun. Although I knew what it was, I still felt anxious.

A few minutes before totality – the period during a solar eclipse when the Sun is completely blocked by the Moon – the wind stopped and the ambient light level plummeted. We looked up through our special solar filters as the solar sliver disappeared to reveal the ‘diamond ring’ – a dazzling point of light with a thin, pink halo surrounding the dark lunar disc. About 100 people let out one simultaneous gasp when the corona appeared.

As my eyes adjusted to the dark, the corona seemed to grow until its longest streamers spanned about eight solar diameters. I was struck by the beauty of the event unfolding before me, completing my photographic exposures by touch while my eyes soaked up the spectacle above.

My overloaded senses slowed the three minutes of totality and it felt like an hour. Then it ended with another dazzling diamond ring. I lay on the sand thinking: “I’ve got to do this again.” I was hooked.

Overcrowded, overclouded for the solar eclipse

In Ceduna, to the east of the Nullarbor, a town of about 3600 people, 13,000 eclipse chasers waited, hearts pounding. The shadow was only minutes from the coast but it was the threatening cloud, not the approaching eclipse, which was raising stress levels. According to the advice issued two years earlier by eclipse weather guru, Jay Anderson, “the Great Australian Bight is a cloudy place in December.” He was dead right.

Ceduna pharmacist Ken McCarthy remembers the day. “After about two years preparing for the eclipse, the town was expecting 20,000 visitors but only about 13,000 actually showed up because of the cloud,” he says. “The volunteering spirit of the Sydney Olympics caught on and many locals acted as hospitality guides.” Ceduna turned its sporting ovals into tent cities and used the clubhouse kitchens for catering. The main street of Ceduna was closed to host a street party on eclipse day.

Among the thousands in Ceduna was solar-eclipse researcher Jay Pasachoff, Professor of Astronomy at Williams College, Massachusetts, usa, who has observed 24 total eclipses. He doesn’t like the expression ‘eclipse chasers’, preferring to describe them as ‘eclipse preceders’, because they position themselves ahead of the shadow and wait its arrival.

The cloud now threatened to spoil everything. Jay knew the risks but years of planning had gone into this expedition and with a team of 18 researchers to house, feed and manage, and a huge amount of equipment, it was now or never.

“Just minutes before the eclipse, the cloud broke up enough that the people at the north end of town got to see it,” Ken told me. Although the people at the south end were “clouded out”, for those who were fortunate to witness it “it was a once-in-a-lifetime experience”. It was a big, though short-lived, injection of cash into the local economy. “We were surprised at how quickly they came and then left after the event,” Ken said.

Paths of solar eclipses from 2002 – 2025. (Credit: Australian Geographic cartography)

Solar eclipse: mass spectacle

Though eclipses have been observed and recorded for thousands of years, eclipse chasing began only about 150 years ago. In 1851, hundreds of astronomers travelled to Norway to see an eclipse, marking, perhaps, the first great eclipse expedition. From then on, expeditions have been pursuing most of the world’s eclipses in accessible locations.

In June 1973, a modified Concorde airliner took seven astronomers on board to track an eclipse. The aircraft had viewing ports in the roof for observing the eclipse overhead. Flying at its maximum speed of 2400km/h at an altitude of 17,000m, the Concorde flew a short course across the curved eclipse path, as if it were cutting a corner on a winding road. Across sub-Saharan Africa, from Mauritania to Chad, the Concorde managed to stay in the shadow for 74 minutes before being overtaken.

During the 20th century, a movement of amateur astronomers and nature lovers began chasing eclipses around the globe for sheer enjoyment. By the end of the century, the number of participants had swollen to tens of thousands for each eclipse. Up to 40,000 people visited Africa in June 2001, and it’s thought as many visited Australia and Africa to see the eclipses in December 2002.

Start eclipse chasers talking about their obsession and the superlatives just roll off their tongues. On the Today Show, a New York gynaecologist, Joel Moskowitz, described his experience during the 2003 eclipse flight to Antarctica as being “better than sex”. The eclipse was short, only 32 seconds.

Just as the 2002 eclipse was ending in Ceduna, the leading edge of the long oval shadow crossed the Stuart Highway near Lake Gairdner, 80km west of Woomera, where thousands more had gathered. In the crowd stood Italian adventurer Vittorio Napoli. Like a modern-day Marco Polo, Vittorio sets out a couple of months ahead of an eclipse, packing a foldable bike in his luggage. He saw his first eclipse from Salerno, Italy, when he was four and now works as a short-term contractor so he can take time off to chase eclipses. He follows eclipses because, “they are the greatest spectacle of nature and give me an excuse to explore the world”.

When in 2001 I first met Vittorio, he’d travelled from Italy to Spain, taken the ferry to Morocco, gone overland down the coast of West Africa then across the Ivory Coast to Gabon. Using a combination of bike, ferries, trains and buses, he visited 18 countries and cycled about 2000km of the total of his 11,000km journey.

Knowing where to be for a solar eclipse

Canberra-based amateur astronomer Dave Herald is an eclipse ‘edge-dweller’. While thousands on the Stuart Highway positioned themselves between Wirraminna and Coondambo, SA – about 80km west of Woomera – on the centre line of the eclipse where duration was longest, Dave and his colleagues put themselves 8-10 km up or down the road, just a few kilometres inside the northern and southern edges of the eclipse path. They timed the appearance of Baily’s Beads – the small flashes that occur when the edge of the Sun is seen through valleys on the Moon’s rim – using the time code in their video cameras.

Thousands more had congregated in Lyndhurst, 250km north of Port Augusta. Eclipse weather guru Jay Anderson, following his own advice to stay away from the coast to avoid cloud, was there guiding one of the many commercial package tours that came to sa on the day. They witnessed a wonderful eclipse as the Sun perched just 4 degrees above the horizon. The umbra, the eclipse’s shadow, was now accelerating very rapidly towards our group at Cameron Corner.

Seasoned eclipse chasers know that being somewhere in the path is only half the battle – finding clear skies is the other half. Jay, a meteorologist with the Prairie Storm Prediction Center in Winnipeg, Canada, usually issues tornado, windstorm and blizzard warnings. A keen amateur astronomer and eclipse chaser, he accidentally became a world expert on eclipse weather prediction.

A 1979 eclipse was going to be visible from his home, so he collated climate data and wrote a weather analysis for North America. He gave a copy to a friend and some months later the US Naval Observatory called for publishing permission. “There’s just one problem,” the caller said. “Our copy has been photocopied so many times we can’t read it.”

Jay has been preparing weather predictions for eclipses ever since. He’d found that the rapid cooling that takes place during the start of an eclipse will often create its own weather effect. Wind is normally slowed by friction with the ground, but during an eclipse, air and ground both cool. This difference causes a temporary loss of friction, so cooling air becomes denser, occupying less space and sucking in the air under the travelling shadow. Observers experience a sudden short-lived increase in wind speed.

Solar eclipses: strangely uplifting

If you think of solar eclipses, you’ll conjure up a mental picture from a ground-based reference point. Viewed on a global scale, the picture changes dramatically. The shadow crossed the Indian Ocean travelling at about 3000km/h. By the time it reached Ceduna it was accelerating rapidly and had reached 23,000km/h. At Lindon station, near Cameron Corner, we had 27 seconds of totality. We watched the umbra travelling in excess of 120,000km/h as it passed over us and left the Earth’s surface, lifting into space.

The axis of the conical shadow was almost parallel to the Earth’s surface as it approached us, giving us the impression of standing in a long tunnel. It was an impressive sight and that’s why we chose such an extreme observing position – near the end of the path. The shadow’s 12,000km journey ended 160km past our location. It covered just 0.14 per cent of the Earth’s surface and travelled around the world in three hours.

Our group comprised seven novices and seven experienced eclipse chasers who’d collectively witnessed more than 80 eclipses.

The first view of the corona is a moving and inspirational experience. That’s why, for so many around the world, eclipse chasing is such an uplifting, even a spiritual, thing. Nature’s grand spectacle is an elixir for the mind and the soul. Once they’ve seen it, most people seek to repeat the encounter and some continue to follow eclipses for the rest of their lives. Take it from me, it’s a wonderful way to see the world and meet people. See you in the Top End in 2012.

Source: Australian Geographic, Issue 78 (Apr – Jun, 2005)