Eclipse chasing: four minutes of bliss

By AAP/Nicky Park with AG STAFF 16 July 2010
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Australian astronomer Mark Rigby chases an eclipse all the way to Easter Island.

AUSTRALIAN ASTRONOMER MARK RIGBY is an eclipse chaser. In his most recent quest, the Brisbane-based stargazer flew to Easter Island for four minutes and 41 seconds of bliss.

He slipped away from the thousands of people gathered on the remote Pacific island and found a vantage point behind a cluster of volcanic rocks. “I just decided on the spur of the moment that I didn’t want to be surrounded by people,” Mark says. “I wandered around the back and clambered over some volcanic rocks and sat down with waves crashing just below me, and I was totally on my own with this visual spectacle.”

Mark, the curator of the Sir Thomas Brisbane Planetarium, sighted his first total solar eclipse in 1976, when the Australian State of Victoria was cast into darkness for a few minutes. Among the eight total solar eclipse chases he’s been on, he recalls staring with “curious locals” in Port Moresby, Papua New Guinea, in 1983, braving chilly winds in 2002 in Ceduna, South Australia, and standing in the desert of Libya in 2006.

Just after 2pm on Sunday 11 July, local time, he added to his list a solitary spotting on Easter Island. The island is one of the most remote inhabited places on the planet, 9000 km west of Sydney in the Pacific Ocean.

In the midst of an eclipse

“YOU’RE LOOKING UP AT the Sun, and as it rapidly gets dark in those last minutes it’s dramatic,” Mark says. “The Moon’s shadow was racing across the ocean towards you, and then you started to see things like planet Mercury off to the side of the Sun… Venus [was] very bright, and then you had the brightest star of the night sky, Sirius, almost above us.”

And that was just what was happening in the sky over the Pacific Ocean – he has heard people scream, while others stare in silence and animals go about their nocturnal routines. “No one person can keep up with everything in a total solar eclipse. There are too many things happening,” says Mark, who has been working at the Brisbane planetarium for 25 years.

“Time goes fast. You want to see all the different visual affects that can occur … and at the same time you’re also trying to look at the surroundings. No eclipse is the same, they’re all different in some way – how dark it gets can vary, and of course the duration can vary – so you are up against the clock.”

The shadow, or umbra, during this week’s eclipse began to fall at 18:15 GMT (04:15 AEST Monday) about 700 km southeast of Tonga, as the eclipse zipped in an easterly arc, cloaking Easter Island at 20:11 GMT (06:11 AEST).

It finished with a pass across southern Chile and Argentina, where it came to an end at 20:52 GMT (06:52 AEST) just before nightfall in Patagonia. About 4000 tourists, scientists, photographers, filmmakers and journalists flocked to Easter Island – a World Heritage site of only 160 sq km – doubling the barren island’s population.

Waiting for the next eclipse

THE SUN IS 400 TIMES wider than the Moon, but it is also 400 times farther away. Because of their symmetry, the lunar umbra that falls on the face of Earth is exactly wide enough to cover the face of the Sun.

“It’s often described as a bit like twilight, but the eerie light goes all around you, right around the horizon,” Mark says. “It looks like a hole in the heavens.”

He said the “awe-inspiring spectacle” of a total solar eclipse only occurred on the same point on the Earth about once every 370 years, but they won’t go on forever. “There will come a day in hundreds of millions of years where there will be no more total solar eclipses, because the Moon is gradually drifting away by several centimetres a year… In hundreds of millions of years, the Moon will not cover the Sun’s disc any more.”

Mark has spent decades scouting out exotic locations on his eclipse-chasing missions, but for his next big one, in November 2012, he won’t have to travel beyond his home state.

Australia was treated to its last total solar eclipse in December 2002. North Queensland will host the next in 2012, and Sydney will cop one in 2028 – all Mark rattled off without hesitation. “It will be nice to have one on home turf.”