International Year of Astronomy -
The Problems of Pollution

Along with the word “environment”, “pollution” is an IN word just now. Unfortunately words often “mask the act”, to quote a local poet; either that or we use some words with such abandon as to deny them their true significance. Two other such words of the moment are: “actually” and “issue”.

I do not want this feature to degenerate into an assault on the abuse of language, but I think it important we understand that through word misuse we frequently lose the argument. Pollution is a problem, not just an issue.

The practical optical astronomer working from the surface of the Earth faces pollution problems from excessive artificial light scatter and from aircraft condensation trails.

Much of the former could be eliminated, without detriment to their purpose, through sensible engineering practice; indeed we have seen some improvement from this angle. (The British Astronomical Association’s Campaign for Dark Skies under the stewardship of Bob Mizon works hard to this end. See Figs. 1 & 2.)

Fig. 1 - Rousay Community School exterior lighting: October 2007. Click on the image for an enlargement.	Fig. 2 - Rousay Community School exterior lighting in December 2008 following the fitting of an environmentally friendly lighting system. (Thanks are due to Orkney Islands Council for replacing the offending lamps.) Click on the image for an enlargement.

On the other hand, the recreational use of light is more difficult to define and control; I am thinking of laser beams, sports facilities (floodlighting), fireworks, airborne “Chinese lanterns” and so on. Unfortunately astronomy is still a minority interest; as a result few show much interest in light pollution.

Aircraft condensation trails fall into another category all together since short of banning the use of aircraft worldwide there is little or nothing one can do about the problem. We might argue the implications for the environment of gross aviation practice until the chickens come home to roost, which they are doing in ever increasing numbers. Dedicated sky watchers simply have to grin and bear it.

I gave up flying (apart from the occasional island hop) long ago - I felt obliged to do this on principle. Much of the research in which I have been involved over the past fifteen years has to do with monitoring the impact aviation is having on the upper atmosphere.

Images 3 – 10 illustrate some of the visible effects from condensation trails. Under certain atmospheric conditions the trails disperse causing only temporary transparency difficulties for the observer. But the “invisible” emissions are still there generating both short-term and long-term havoc.

Fig. 3 - A view of the sky from Brinsworth, Yorkshire, December 2006. But for the trails the sky would have been clear. Photo: Ann Chapman. Click on the image for an enlargement.	Fig.4 - The sky looking south, Springfield, Rousay, Orkney, August 2003 – the sky awash with contrails from transiting civil aircraft. Click on the image for an enlargement.

Fig. 5 - Not all pollution from trails is caused by civil aircraft. In Britain the MoD, in collaboration with NATO, hold special exercises lasting ten days or so and taking place on average three times a year. Here is an example of aircraft circling as seen from the region of the Rousay Jetty, March 2006. Routine military training also gives rise to similar effects. Click on the image for an enlargement.

Fig. 6 - Thin, high cloud possibly unnoticed by the casual observer and resulting from the spread of condensation trails. Note the short trail close to the centre. June 2, 2009, Rousay. Orkney. Click on the image for an enlargement.

Fig. 7 - Remnant from a single contrail. May 24, 2009, Rousay, Orkney. Click on the image for an enlargement.	Fig. 8 - Contrails can give rise to some startling sunsets. Rousay, January 2009.Click on the image for an enlargement.

Fig. 9 - The day of May 31, 2009 saw the sky completely dominated by spreading con trails. Here is a late evening shot with mist forming on the central hills of Rousay: an aircraft appears “set” on having the last word! Click on the image for an enlargement.	Fig. 10 - At cross-purposes? A fine, early morning mid-October 2006 in danger of being marred by condensation trails. Rousay Orkney.Click on the image for an enlargement.

In common with the motorcar, aircraft are at odds with the environment (as indeed are most industrial practices worldwide). Our economies have been fashioned on the principle of unlimited growth. It should be obvious to any thinking person that this sort of attitude is unsustainable on a relatively small planet of finite size and limited resources.

In this International Year of Astronomy it would be useful and heartening to find that more of the world’s population become aware of our planet’s fragility.

Fig. 11 - Poles apart! As it should be - the Sun rising into a clean sky: Winter solstice (2006 December 21, 09h 20m UT). Rousay, Orkney. Click on the image for an enlargment.

JV 5/06/09