Monday, December 04, 2006

AURORA by Brian Hodgkinson

(Note: This is the September Assignment. Our members had a choice of a number of topics. We were to choose an unfamiliar topic and perhaps research it and produce poetry or prose. Brian chose Aurora.)

It had been a magical evening. The six of us, replete after a wonderful meal at one of Hobart’s best restaurants, had come out into the clear air of the late evening.

“Let’s go up the mountain” someone had said.

And so we all agreed to take the winding mountain road, up and through the tree-line, to come out on the very summit, wrapping our arms around the girls to shield them from the chill air.

The city lay below us, sparkling in the clear atmosphere – with, as my poet wife said, “cars sliding like jewels, necklacing the streets”.

And then we turned, and there, towards the south, the sky was hung with curtains of light. Shimmering and silently moving, as the proscenium of some heavenly theatre, with colours so subtly evanescent, revealing the brightness of the southern stars through finest watered silk, the sky danced and sang above us.

We all held our breath in awe. For what seemed like an aeon, the display showed from horizon to horizon, until slowly it faded, leaving us bereft, to slowly turn and return to the more mundane workaday world.

Of course, scientists hold a more prosaic view.

“The belief has been that auroral displays are caused by high-speed charged particles such as protons and electrons issuing from active regions of the sun and penetrating into the auroral zones by the action of the earth’s geomagnetic field.

This belief was first proposed by Eugene Goldstein as early as 1881, and received strong support from laboratory experiments carried out by Kristian Birkeland. The full mathematical formulation of the problem was given by Carl Störmer, and is known as the Birkeland-Störmer theory.

Of recent years a new theory has been proposed by a few workers, taking into account the newest research into magnetohydrodynamics, which assumes the penetration of plasma gas from the sun into the earth’s magnetic field, travelling to an altitude of some 100 km in the auroral zones and forming dense cores of ionization along geomagnetic lines, thus causing auroral emissions due to reactions with oxygen and nitrogen, the main constituents of the upper atmosphere.

But there remain many questions regarding these theories and the detailed mechanisms involved. The Van Allen radiation belt may play an important part, and the varied colours observable in auroral displays may be due to chemical constituents in different parts of the atmosphere – this latter having been deduced from spectroscopic analysis by Anders Ångstrom as long ago as 1867.”

Of course, both of these approaches differ from that of the transport enthusiast. For him, the RSV “Aurora Australis” is a specialised scientific research vessel designed for research into many aspects of the Antarctic continent, and to supply the three Australian bases on the Antarctic mainland and on Macquarie Island.

She can carry a full complement of 135 persons, including up to 70 scientists together with their necessary equipment. She is also designed as an icebreaker, with a strengthened hull capable of breaking through ice up to 1.2 metres thick. She is based on the port of Hobart, and made her maiden voyage in the southern winter of 1991, calling at Mawson Base on 12th November, at Casey Base on 22nd December, at Macquarie Island on 17th of January, and at Davis Base on 9th February.

Brian Hodgkinson ©