The March Sky


The Total Solar Eclipse of 2002 December 4

This had been the second total solar eclipse of the 21st century, with a maximum length of totality of 2 minutes 4 seconds over the southern Pacific Ocean. The path of totality was a mere 85km wide, lying primarily over ocean, with land-based observation possible only at either end of the path: from southern Africa or southern Australia. In the former case, however, the chances of good weather were slim as the African rain season was at its height. No successful observations had been reported from the east African coast, although observers had enjoyed some success in Botswana and Zimbabwe, with a 1 minute 15 second totality at 30° altitude. Along most of the track, cloud cover had exceeded 50%, and rough seas precluded any stable camera mount.

The greatest success had come from Australia, where the altitude of totality was 9° and cloudiness 25-30%. Observing parties had favoured three sites in particular: Ceduna, at the western coastal extreme of totality's path; the Woomera Prohibited Area; and Lyndhurst, towards the northeastern extreme of the totality path. Lingering cloud at Ceduna had led many to journey along the path of totality towards Lyndhurst, however.

Four substantial sunspot groups had been visible four days before the eclipse, raising hopes for coronal flares during totality. In the event, prominences were visible all around the solar disc. At the end of totality, the diamond ring grew over a broad front, rather than emerging from a single point. Dr Mason then proceeded to invite a number of Association members to present their observations.

Mr Mike Maunder reported that he had observed from Ceduna, on the southwestern Australian coast, attempting to film totality with a reflection across the sea. Whilst much of the partial phase had been clearly visible, the 33 seconds of totality were unfortunately partly obscured by cloud. He had hoped that his footage would be reported by the BBC on the Sky at Night, but sadly it was dropped from the schedule at a late stage.

Mr Nick James had stayed with a large number of Explorers' Tours observers at Woomera, central Australia. The group had been greeted by kind weather. The eclipse path had not passed through the main settlement at Woomera, and so the chosen observing site had been the Woomera Prohibited Area – a former British rocketry and nuclear test site. The area was incredibly isolated, but the flat horizon was ideally suited for observation of the low altitude totality phase. To assist in this aim, observers had formed a long line to avoid obstructing one another's views. Besides his eclipse observing, Mr James had also taken a keen interest in the surroundings at Woomera, which included the launch pads for both military and space rocketry. Following the 100% failure rate of the European multistage satellite launcher, the site had fallen into disuse in the 1970s.

Mr Nigel Evans presented a second report from the same observing site. He had optimised his use of the 27 seconds of totality by wiring five cameras to his Psion PDA. This fully-automated setup allowed him to effortlessly take a range of photographs, including strings of images at different exposure settings. His results included Hα and He ionisation maps, revealing strong prominences in the corona. He reported that high winds had limited his seeing to an arcminute, and that he had also overestimated aperture settings, but his results were of superb quality nonetheless. Most notable of all was video footage of the Sun setting during the partial phase, with a "continuous green flash" caught on camera, as the crescent – shaped much like a dolphin fin – passed out of sight.

Finally, Mike Foulkes and Derek Hatch reported that they had been based at Lyndhurst, a small settlement comprising of no more than a couple of buildings surrounded by dry, flat, desert. They had used a digital SLR camera with a wide-angle lens on an equatorial mount, and recorded a straightforward second contact, clear images of Bailey's beads, and a double diamond ring at the close of totality.

Following the applause for the superb results presented in the reports, the President invited Dr Jon Loveday, of the University of Sussex, to present the afternoon's main talk.






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