Posts Tagged ‘Yerkes Observatory’

This morning (Tuesday 19th of February) I heard this item on the news about how the Brecon Beacons National Park in South Wales had been granted dark sky status by the International Dark Sky Association. This is wonderful news for Wales. Earlier I had a phone call from the BBC asking me to talk about this on this evening’s news. They are planning to film the item live up in the Brecon Beacons. In the next couple of days I will try and do a video capture of the item and post it on YouTube.


Light Pollution at Yerkes Observatory

I first got involved in light pollution work in 1998. I remember it distinctly, because it was the same week my 2nd child was born. At the time I was working at the World famous Yerkes Observatory, part of the University of Chicago. Yerkes houses the World’s largest lens telescope, the great 40-inch refractor and is where many famous astronomers, including Edwin Hubble, have worked. I was lucky enough to work there for 6 years as a post-doctoral researcher, and I used to try to use the Observatory’s 41-inch (1-metre) reflecting telesocpe for some of my research.


I started using the 41-inch in 1997, but by 1998 it became obvious to me that my images were not as good as they should be, and so I started investigating the darkness of the skies at the Observatory. I took a series of horizon photographs from the catwalk of the 40-inch, and the results surprised me. Yerkes Observatory is about 75 miles North North-West of Chicago, so I fully expected the direction to the South South-East to be the brightest part of the horizon. But in fact it was not, the brightest parts were to the East (the city of Lake Geneva) and to the North-West (the city of Delavan), both within about 7-8 miles of the Observatory.

I knew there was little I could do to influence the light pollution coming from Chicago, but discovering that the main problem was local gave me hope. I consulted with the numerous pages at the IDA website, and drew up a lighting ordinance. I first gave a presentation about the problem to the Village Board of Wiliams Bay, where Yerkes is based. Not surprisingly, with the over 100-year old Observatory in their community, they were very supportive and agreed to adopt the lighting ordinance. I then took it to the other communities, Delavan, Lake Geneva and Elkhorn. The major light polluter was a greyhound racing track about 6 miles North-West of the Observatory on the outskirts of Delavan.

On one occasion the greyhound track’s light pollution prevented a potentially important discovery. In the period 1998-2002 a hot area of research was determining the nature of gamma ray bursts (GRBs). At the time, the satellite which would discover these in the X-ray, a satellite called BeppoSAX, didn’t have enough positional precision to know exactly which object had caused the burst. So it was important to try to find the optical counterpart, something the 41-inch was ideal for as it was under-utilised and so usually available at short notice. One particular GRB in 1999 would have been visible to us at Yerkes, but as bad luck would have it, it was in the direction of the greyhound track, a part of the sky where the light pollution rendered seeing it impossible.

I arranged a meeting with the manager of the greyhound track to discuss this problem. By this time I had got a light meter via a grant from the American Astronomical Society small grants program, to investigate light pollution levels in the locality. I measured the lighting levels of the metal halide lights the greyhound track had on in its car park all night every night (even though it was only open for races on a Friday and Saturday evening!). They were 10 times (yes, ten times) the level recommended by the IDA and the American Society of Lighting Engineers for a car park of its size. They were even above the level recommended for reading in one’s house!! Even though the car park was tarmac (“black top” as Americans would call it), reflecting maybe 10% of the light from this black surface was leading to a huge dome of light above the area. On the nights when there were races the problem was even worse, as the track itself would have bright stadium lights on too.

I calculated the amount of money the track was wasting by having these lights on all night, and it was in the tens of thousands of dollars per year. Given that the track was making a loss, I thought this might be the best argument to use with the manager. I didn’t think he would particulary care about whether we could or couldn’t see the afterglow of a GRB, but I was sure he would be concered to know that he was wasting so much money.

By the time I left Yerkes Observatory in 2001 most of the communities had adopted the lighting ordinance. The only one which hadn’t was, unfortunately, Delavan.

Light Pollution in Wales

I moved back to Wales in 2001, to the Cardiff area. Of course Cardiff is far more urban that where I had been in Williams Bay, Wisconsin. So initially I thought doing something about light pollution back here was a lost cause. But then I realised that there were areas near Cardiff, like the Brecon Beacons and Pembrokeshire (where I grew up) which were still dark. It was growing up with the dark skies in Pembrokeshire which allowed me as a child to indulge my passion for astronomy and see the stars properly.


I think it was in about 2003 or 2004 that I was first invited to give a talk to an astronomical society based in Mynachlog Ddu in Pembrokeshire. This is one of the darkest places in the Disunited Kingdom. It was darker than the skies I had lived with at Yerkes. Another extremely dark place is, of course, the Brecon Beacons, only an hour north of Cardiff. In about 2006 I wrote to Rhodri Morgan, the then First Minister of Wales, about light pollution and how Wales could profit from some naturally dark skies by preserving and promoting them.

Some 90% of the population of the Disunited Kingdom live in areas where there is substantial light pollution. This means they do not get to see the sky in all its glory. But, of these 90% many thousands are interested in the sky. They are members of astronomical clubs, but struggle to see what they are interested in. The Brecon Beacons will now be able to attract these kinds of people, so called dark sky tourism is a growing area and one which Wales can capitalise on.

The night time sky is part of our shared heritage, and connects us with our ancestors thousands of years ago. It is where myths and legends have been played out by our great story tellers. Each civilisation has its own stories about the pattern of stars we see in the sky. But in the last 50 or so years so much of this shared heritage has disappeared from view due to bad lighting. Hopefully we are slowly beginning to do something about it.


Here is a YouTube clip of the interview

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In November of last year (2011), I have a talk to Swansea Astronomical Society on the early history of Yerkes Observatory. I blogged about that talk here.

Last night (Thursday 8th of November) I gave a talk to the same society with the title “ George Ellery Hale : The greatest Astronomer of the 20th Century?“. The title is deliberately provocative. In the talk I attempted to show Hale‘s main achievements in his productive life. There were many, but this slide summarises the main ones :

A summary of Hale’s main achievements in his astronomical career

Here is a gallery of all the 32 slides in the talk.

My conclusion, in the last slide, is that maybe Hale wasn’t the greatest astronomer of the 20th Century, but probably the most important. Without Hale, Yerkes Observatory would never have existed, nor Mount Wilson Observatory.

Who do you think was the greatest astronomer of the 20th Century?

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