George Alcock goes to Antarctica

2021 October 1

Jonathan Shanklin

Although the name of George Alcock is well-known in the astronomical community, his interests were wide-ranging. The 2021 George Alcock Memorial Lecture, given online at a webinar of the BAA on 2021 May 26, delved into a few of those interests that he might have pursued on a visit to Antarctica. An extract from the full version of his article on the Lecture, published in the 2021 October BAA Journal, is given here. Click above to download a PDF version of the full article, including Mr Shanklin’s account of his discovery of the Antarctic ozone hole.

The annual BAA George Alcock Memorial Lecture is usually on an astronomical topic that is associated with the observing interests that George had, mostly covering comets, meteors, variable stars and novae. When I gave my first such Memorial Lecture, I thought it worth combining some of these and his other interests that are recounted in Under an English Heaven, a book about George written by Kay Williams. I chose the title of ‘George Alcock goes to Antarctica’ so that I could weave in some of my own professional work carried out on the continent. It was a singular honour to be asked to give a second lecture on the same topic and this article recounts some of what was said.

George lived in the small village of Farcet, near Peterborough; the area would have been largely rural during his lifetime, though with brickworks not far away. On occasion the smoke from these works did degrade his observing conditions. Many of his observations were made with wartime tripod-mounted 10×80 binoculars. These were probably similar to a pair that I used at the Cambridge University Observatories, which had a finder bracket that glowed in the dark to provide an aiming line – it was only later, when a Geiger counter went berserk near the device, that I realised that the luminous paint was radioactive

Many of the drawings of comet tails that he made with the binoculars drew scepticism from the seasoned astrophotographers of the day, as their long-exposure images showed none of the fine detail seen by George. It was only with the advent of the much shorter exposures practicable with electronic devices that people realised that George did have unusually acute eyes and that such fine structure was real.

At the time of the lecture, a nova had been discovered in Cassiopeia and had just reached naked-eye visibility. I contrasted this with nova NQ Vulpeculae, discovered by George in 1976, which faded quickly after discovery. Surprisingly, the new Nova Cas 2021 was so slow that it was still visible in binoculars five months after discovery.

Another interest of George was natural history; he made notes and watercolour sketches of what he saw. My artistic skills are limited, but I am vice-president of the Cambridge Natural History Society and the Botanical Society of Britain & Ireland’s recorder for the ‘old’ county of Cambridgeshire. George also had an interest in church architecture; my interest in churches covers ringing their bells and recording the flora of their churchyards.

George made many meteor observations, often in collaboration with others, to triangulate meteor heights or help confirm radar observations made in the then-new field of radio astronomy. One such collaboration involved making observations with a ‘reticule’ in a worldwide programme, organised by the Byrd Antarctic Expedition in 1934.

On many of my visits to Antarctica, transport to the Falkland Islands was by the RAF, which George served with during the Second World War (on his travels, he saw Vesuvius erupting and made sketches of the eruption plume). The flight to the Falklands often stopped to refuel at Ascension Island, a dormant volcanic island in the mid-Atlantic. On one occasion I arranged to stay there for a few days to see some of the sights of the island. These included lava-eroded channels like lunar rilles and ‘devil’s eyeballs’, where volcanic fragments had landed in dusty pumice. Also on the island is Mars Bay, where Sir David Gill measured the parallax of Mars in 1877.

Arriving in the Falklands, one of the landmarks is Christ Church Cathedral, Stanley and I am sure that George would have sketched it.

On one visit our ship was anchored in Stanley Harbour and I was lucky enough to see a display of noctilucent cloud, something that very few people have seen in the southern hemisphere as there is little land at the right latitude. The open skies of Antarctica have some similarities to those of Fenland (though there are no trees!). George often drew cloudscapes and one of his drawings, showing crepuscular rays, is remarkably similar to an Antarctic scene showing the same features.

In 1991, a meteorite fell in daylight at Glatton near Peterborough, not that far from where George lived. According to the finder it fell silently with no sonic boom, so George would not have heard it. He would however have been aware of other meteorites being found in Antarctica. Although these fall randomly across the continent, slowly flowing ice can concentrate them in certain regions where there is strong sublimation from the surface. These ‘blue ice’ zones occur near some of the mountain ranges and the meteorites are found on or near the surface. Search programmes are run by several countries to locate and document these finds, which present uniform samples of often pristine meteorites.

The Antarctic

Although several countries, including the UK, have territorial claims to parts of Antarctica, these are held in abeyance under the Antarctic Treaty. The continent has become devoted to science and, increasingly, tourism. Mineral exploration is banned under the Treaty.

To get there, there are two options. You can travel by ship – which can be an unpleasant experience as it involves crossing the ‘Furious Fifties’, one of the stormiest ocean passages in the world – or alternatively, you can fly. Some Antarctic stations such as the British Antarctic Survey’s (BAS) Rothera Research Station have a gravel runway, whilst others such as the Russian Novolazarevskaya Station have a ‘blue ice’ runway. This was the landing point on my last trip down, which was in a Boeing 757 where the worst seating was business class! From these stations you transfer to a smaller plane to get to the final destination and in the case of my last flight this meant a ski-fitted, unpressurised DC3 that flew at 14,000ft to our destination of Halley Research Station.

Life on an Antarctic station can be quite pleasant. You are living where you work, provided with all the necessary clothing and catering is mostly by professional chefs. On the smaller stations there may be no chef, so station members take it in turns to cook for everyone else, as also happens when the chef gets a day off. Cooking for 40 can be stressful, but I did have people coming back for seconds!

There is usually time for some recreation: pool when the weather is bad or skiing on the nicer days. The type of skiing depends on the local terrain and the availability of Ski-Doo drivers. You can go cross-country skiing by yourself, but you can also be towed on the flat behind a Ski-Doo for skijoring, or towed to the top of a hill for a spot of downhill. The stations often have trained mountain guides to assist scientists visiting remote stations and they may be willing to take recreational parties to the nearest crevasse, to practice techniques. In the extreme, you can even go for a quick dip, followed by a cold shower!

The Antarctic wildlife is fantastic, particularly along the Antarctic Peninsula and offshore islands. (At Halley however, the temperature rarely gets above 0°C and all water is frozen, making it a virtual desert – there is little wildlife apart from the odd stray penguin or overflying snow petrel.) George made many sketches of his local fauna and he would have been fascinated by the albatross, penguins, seals and whales that are largely unafraid of people. At Bird Island, you are living in the middle of a seal colony, with petrels nesting in tussac grass behind the station and there are nesting wandering albatross further inland. One memorable night, I got up in the early hours to observe a comet under totally dark skies, with the sounds of all this wildlife surrounding me.

Meteorology

George had an interest in meteorology and ran his own weather station. My formal role with the BAS was to run the meteorology and ozone-monitoring programme. Antarctic weather can change rapidly from crystal clear skies to a raging blizzard, so you have to be aware of changing conditions. As an observer you also get to see a wide range of meteorological phenomena: fogbows, rainbows (rarely!), halo phenomena, mirages and, if you are lucky, the green flash as the final fragment of the solar disc drops below the horizon. At the south pole the Sun sets very slowly, so observers there have been able to see the flash for many hours. As the Sun nears the horizon, a look in the opposite direction shows the rising shadow of the Earth as a grey band along the horizon. On occasion, this may intercept the Moon to give an eclipse.

As darkness falls, you get the splendour of the southern skies – Orion doing a handstand, the sting of the Scorpion and the Milky Way arching overhead. The two Magellanic Clouds do indeed resemble small, faintly illuminated cumulus clouds, and the Southern Cross becomes a familiar sight. By carefully timing my visits towards the end of the season I have observed a few comets from Antarctica, most notably obtaining the first sighting of 1P/Halley from the continent. In 2011 December the bright sungrazer 2011 W3 (Lovejoy) was visible from the southern hemisphere, but I was too far south and it was not quite bright enough to be visible in daylight.

The weather observations are made by a mix of manual and automatic stations, with details of humidity, pressure, temperature, wind speed and direction sent back via satellite. Details of weather type, clouds and visibility are added when observers are present. Summer temperatures, particularly at Peninsula stations, are often little different to a British winter, but the solar radiation input is more like a British summer, so sunblock is essential. The Antarctic winter is very different, and whilst temperatures only get to –50°C at Halley, the Russian station of Vostok has recorded the lowest temperature on the planet at –89.2°C. There, the observers essentially have to put on a spacesuit to venture outside.

The mean temperatures from the stations contribute to the network monitoring global change. There is no doubt that mean temperatures have risen across the planet, and parts of the Antarctic Peninsula have warmed by 3°C over the 60 years with observations. The temperature changes are however not uniform and there has been something of a pause over the last couple of decades. There are also regional variations, so that the mean temperature at Halley has not changed significantly over the same period. Local response to the Peninsula warming is obvious, with ice cliffs near the stations and most glaciers in retreat. Some ice shelves have fragmented as a consequence of the warming, but others have done so as part of a natural process of calving.

Many processes cause changes to our climate. Meandering ocean currents can give rise to decadal variations. Volcanic eruptions, particularly the biggest ones, can give rise to short-term cooling at the surface. Our Sun is a variable star and while its total output does not vary sufficiently to explain the temperature change, second-order effects may explain some variability. That leaves what we are doing to the atmosphere through agriculture, industry and transport, which all increase the amount of ‘greenhouse’ gases, such as carbon dioxide, in the atmosphere.

To see what happened in the past, Antarctic scientists drill down into the ice to extract cores. By analysing the composition of air trapped in tiny bubbles in the ice, measuring the oxygen isotope ratio of the ice (a proxy for temperature) and dating the ice by counting annual layers, a picture emerges going back over half a million years.

Today, carbon dioxide levels are as much above a normal interglacial level as they were below it during a glacial period. Temperatures during a glaciation were eight degrees colder than during a normal interglacial phase. The rate of change is much faster than in the past – nature took 1,000 years to do what we have done in fifteen. This rapid rate of change makes it likely that many ecosystems will not be able to cope.

Jonathan Shanklin, Emeritus Fellow, British Antarctic Survey

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