Light Pollution

In the mid-1970s, The Toronto Centre of the Royal Astronomical Society of Canada sponsored some research into light pollution, the brightening of the night sky by artificial illumination. This `Sky Brightness Project' produced several documents, which are collected here.

Richard Berry and I wrote a pair of related papers in 1976 about the growth of light pollution. Here are PDF scans of those articles, which were published in the Journal of the Royal Astronomical Society of Canada, Volume 70, Number 3, 1976, starting on page 116. Richard Berry's is titled Light Pollution in Southern Ontario and mine is titled A Simple Computer Model for the Growth of Light Pollution. They may also be found in HTML form (Berry, Pike) at the web site of the Light Pollution Abatement group of the Royal Astronomical Society of Canada.

The picture above, scanned from our article in the February 1978 issue of Sky and Telescope (cited below) shows the state of Southern Ontario light pollution in 1975. Each color step is a factor of the square root of two. The brightest areas are about 6 magnitudes brighter than at the best observing locations. The boomerang shape near the center is the cities of Toronto, Hamilton, and Buffalo around the end of Lake Ontario; the bright spot at left is Detroit and Windsor.

In February, 1978, Sky and Telescope magazine published on pages 126, 127, 128, and 129, a less scholarly article by Richard and me, followed by several pages of encouragement to get people active in fighting the scourge. (Don't be confused: the orientation in the picture shown at the top of this page is correct; Sky & Tel printed the pictures upside down.)

At last, today, it seems the fight is entered; see for example the International Dark Sky Association's web site, as well as the RASC LPA activity and others. A modern, much more ambitious survey of night sky brightness, done by Pierantonio Cinzano, Fabio Falchi, and Chris Elvidge can be found starting here. According to their preliminary research, North American sky brightness increases about 6% per year, half a magnitude in 10 years.