Archive for February, 2013

My favourite Anglo-Welsh poet (a Welsh poet writing in English) is R.S. Thomas. The first poem of his that I came across was when I was 13. In our school English class we read “Cynddylan on his tractor”. It made me angry when I read it. Thomas seemed to be belittling the Welsh. It took me several poems and several weeks to realise that he was attempting to awaken Welsh people’s apathy towards their country.


Thomas was born in Cardiff to English speaking parents. He went to Bangor University, where he read classics. He then went into the ministry, being ordained as a priest in the Church of Wales. Thomas learnt Welsh when he was 30, but he never wrote poetry in Welsh as he felt it was not his native tongue and so he didn’t feel his Welsh was good enough. Despite learning Welsh in adulthood, Thomas became a keen (some would say extreme) advocate of the Welsh language and the need to protect it against Anglo-American domination.

Thomas died in 2000, leaving about two dozen published volumes of poetry, the list is here.

This poem of Thomas’, A Welsh Landscape, is my favourite poem written in the English language. I mentioned it before in this blog, but I did not include the words of this wonderful poem, just a link to where they can be found. I mentioned it in the context of trying to answer my son’s English homework question – “What does it mean to be Welsh?”. If the words and sentiment of A Welsh Landscape resonate with you, then you at least have an understanding of what it is to be Welsh.

Here is the poem in its entirety.

A Welsh Landscape

To live in Wales is to be conscious
At dusk of the spilled blood
That went into the making of the wild sky,
Dyeing the immaculate rivers
In all their courses.
It is to be aware,
Above the noisy tractor
And hum of the machine
Of strife in the strung woods,
Vibrant with sped arrows.
You cannot live in the present,
At least not in Wales.
There is the language for instance,
The soft consonants
Strange to the ear.
There are cries in the dark at night
As owls answer the moon,
And thick ambush of shadows,
Hushed at the fields’ corners.
There is no present in Wales,
And no future;
There is only the past,
Brittle with relics,
Wind-bitten towers and castles
With sham ghosts;
Mouldering quarries and mines;
And an impotent people,
Sick with inbreeding,
Worrying the carcase of an old song.

R. S. Thomas 1913-2000

Which is your favourite R.S. Thomas poem?

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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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Recently I was watching my favourite episode of the wonderful HBO series “From the Earth to the Moon“. This episode, called “1968” charts the turbulent year of 1968, which culminated from NASA’s perspetive in their successfully sending astronauts around the Moon for the first time. The 3 astronauts who got the privilage to be the first human beings to see first-hand the far side of the Moon were Frank Borman, Jim Lovell and Bill Anders.

One of the most enduring images from this mission is the one of a beautiful Earth coming up above the bland grey Lunar horizon – an image which has become known as Earthrise.

Earthrise, as seen by the astronauts of Apollo 8 in December 1968.

Earthrise, as seen by the astronauts of Apollo 8 in December 1968.

In all, Apollo 8 orbited the Moon 10 times, taking detailed pictures of potential landing sites which were used for Apollo 11‘s eventual landing on the Moon in July 1969. During their time on the far side of the Moon the Apollo 8 astronauts had no way of communicating with Earth, and were therefore very much alone in Space. Here is the clip from this wonderful series when they see Earthrise for the first time. If you have not seen either this episode or the entire series of From the Earth to the Moon I highly recommend that you do.

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I was reading a story recently about how The European Union was going to take more stringent action on the shipping of so-called “e-waste” (computers and other electronic goods) to Ghana. Ghana has become the place for computers from Europe to get dumped. When you take your computer to the recycling centre you think you are doing the right thing environmentally. You cannot just dump a computer in a landfill in Europe or the USA (or most other developed countries). So, you take it to the recycling centre.

Rather than recycle the computer, back in the mid 1990s it was decided to ship these old computers to African countries, where poorer people could get to use a computer that would cost one tenth or less of the price of a new one. It seemed to be a win-win situation, it was cheaper to ship the computers than recycle them in the developed countries, and it was felt that developed countries were doing their bit to bridge the “digital divide” by giving the computers to developing countries.

But, sadly, over the years the business became corrupted, and by early in the 2000s the computers were not being used by the people in the developing countries at all, they were being dumped in landfill sites there. Today in Europe, millions of computes that are taken for “recycling” are instead ending up in toxic landfill sites like the one in Agbogbloshie in Accra, the capital city of Ghana.

There are many articles on this problem to be found on the web, but one of the best is this one from Time Magazine.


At these sites, thousands of people scavange for precious metals from the computers, burning away the plastic insulation to retrieve the metals. This leads to palls of acrid and toxic smoke rising into the sky near these dumps. Photographs and news clips that I have seen of Agbogbloshie suggest it is a living hell. Measurements suggest that levels of toxic chemicals are at least 100 times the allowable limits set by the World Health Organisation (WHO).

So next time you take your computer or TV or other electronic device to your local recycling centre, try to find out before you do whether your local authority ships it out to Ghana or some other toxic landfill site rather than doing the proper thing and recycling it properly in an environmentally friendly way.

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Paul Simon is one of my favourite songwriters. In my opinion, along with Bob Dylan and Leonard Cohen, he is one of the best lyricists of the past 40-50 years. His songs with his singing partner Art Garfunkel (as Simon and Garfunkel) are probably nearly as well known as The Beatles’ songs. I suspect much of his solo work is less well known.

I blogged last summer about his seminal album, the amazing Graceland, which is generally recongised as his greatest piece of work. And Paul Simon himself feels his best ever song, of the hundreds he has written, is the song Graceland on that album.

Today I am sharing one of my favourite Paul Simon solo songs, American Tune. I am not sure how well known this one is, it is on his 1973 album There Goes Rhymin’ Simon. Until about 14 months ago I had only ever heard the live version of this song which is on Paul Simon’s greatest hits album Greatest Hits etc., but upon my first hearing it many years ago it quickly became one of my favourite songs by him. Last year I finally got around to buying There Goes Rhymin’ Simon and heard the studio version for the first time. In addition, the “new” version of the album that I bought also had some bonus material, which included a demo version of “American Tune

Paul Simon's American Tune is one  of his moist poignant songs.

Paul Simon’s American Tune is one of his moist poignant songs.

These are the lyrics to this wonderful song.

Many is the time I’ve been mistaken, and many times confused
Yes and I’ve often felt forsaken, and certainly misused.
Ah but I’m alright, I’m alright, I’m just weary to my bones
Still, you don’t expect to be bright and Bon Vivant
So far away from home, so far away from home.

And I don’t know a soul who’s not been battered
I don’t have a friend who feels at ease.
I don’t know a dream that’s not been shattered
Or driven to its knees.
But it’s alright, it’s alright. For we’ve lived so well so long.
Still, when I think of the road we’re traveling on,
I wonder what’s gone wrong, I can’t help but wonder
What’s gone wrong.

And I dreamed I was dying. I dreamed that my soul rose
unexpectedly, and looking back down at me, smiled
reassuringly, and I dreamed I was flying.
And high up above, my eyes could clearly see
The Statue of Liberty, sailing away to sea.
And I dreamed I was flying.

We come on a ship they call the Mayflower,
We come on a ship that sailed the moon
We come in the age’s most uncertain hours
And sing an American tune.
Oh and it’s alright, it’s alright, it’s alright.
You can’t be forever blessed.
Still, tomorrow’s gonna be another working day
And I’m trying to get some rest,
That’s all, I’m trying to get some rest.

This YouTube clip is of Paul Simon performing the song on Parkinson, a long running chat show in the Disunited Kingdom.

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He is the most recognised Paralympic athlete in the World, dubbed “the bladerunner”. He is probably the most famous sportsperson in his native South Africa. But today Oscar Pistorius’ career lies in tatters. The extraordinary news broke onThursday (Saint Valentine’s day) that Pistorius’ girlfriend, Reeva Steenkamp, had been found shot dead at his house in an exclusive gated community near Pretoria, South Africa’s capital city. Yesterday (Friday the 15th of February), Pisotriuss appeard in court to be charged with murder.


The prosecution is pushing for a charge of premeditated murder, his defence are apparently wanting a charge of accidental homicide (or the South African equivalent). Either way, it is difficult to see how Pistorius can avoid a lengthy jail sentence. Given that the defence always suggest the least serious crime they believe they can defend against, it speaks volumes that they are hoping for accidental homicide. Even should Pistorius be found guilty of this rather than premeditated murder, he will serve many years in prison, my guess would be 10-15 years. He is 26.

His athletics career is effectively over. And so is the symbol that he has become of difficulty triumping over hardship, of hope over adversity. Stories have emerged in the last 48 hours of a man with a volatile temper. I do not wish to comment on these stories at this stage, but I can say that Pistorius is obviously a very determined, driven individual. He has fought against the difficulties his double amputations have caused all his life, most notably when he eventually won a lengthy case against the IAAF to be allowed to compete in the Olympics, something he did just last August in London. He became the first double amputee to ever compete on a track race at the Olympics, reaching the semi-final of the 400m against his able-bodied competitors.


That is two sporting icons who have fallen from grace in the past few weeks. First Lance Armstrong, and now Oscar Pistorius.

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Yesterday an extraordinary coincidence happened. As I blogged about here, a 50m long lump of rock (asteroid 2012 DA14) was scheduled to zip past Earth yesterday evening (15th of February) at some 12 kilometres per second at a distance of “only” 28,000 km. Although this sounds like a lot, it is closer than any asteroid that size has come to Earth to our knowledge for many decades.

But yesterday I awoke to the news that another lump of rock had exploded in the air over an area in the Ural mountains in southern Russia near Kazakhstan. Initial reports were that about 500 people were injured, this figure had risen to closer to 1,000 by the end of the afternoon.


Of course some people wondered whether these two events were connected. Well, I can assure you they were not. Earth is constantly being hit by particles from space, as we whizz around the Sun at 30 kilometres per second. Every day some 100 metric tonnes (a tonne is 1,000 kgs) of material enters the Earth’s atmosphere. Most of these are sand-grain sized particles, with the number of larger and larger objects becoming fewer and fewer. It probably follows what we call a power law size distribution, in much the same way as the interstellar dust grains I studied for my PhD do. In fact, at the very small level the particles are interstellar dust grains, it’s only when they become larger that we start referring to them as asteroids or lumps of rock.

What this power-law size distribution means is that larger lumps are rarer and rarer. NASA has calculated the size of the lump which exploded over Russia yesterday to be about 15m, and the damage gives an indication of what something this size entering the Earth’s atmosphere can do. To my memory, this is the first time I know of a meteor explosion causing human casualties. The 50m sized asteroid which thankfully missed Earth last night would have caused far more damage, enough to wipe out a large city. We believe 50m sized asteroids hit the Earth about once every 1,200 years, larger ones even less often. And, asteorids a few kilometres in size, large enough to cause widespread devastation and even lead to global catastrophies seem to happen as rarely as once every few hundred millon years.

The Earth will be hit by an asteorid large enough to cause global devastation, of that I have little doubt. But the chances of it happening when humanity still exists is very remote in my opinion. And, as long as we are vigilant whilst we still exist as a species, there is much that can be done to deflect such large asteorids which are on a collision course for Earth. Unlike the portrayals in movies, probably what we do not want to do is send a missle to destroy a threatening asteroid. Rather, we want to gently nudge its orbit into one which will miss the Earth.


Gently nudging an asteroid so it will miss Earth can be done in a number of different ways, but possibly the most elegant is just to paint one side of it white. This will cause the Sun’s light to reflect off of that side more than the rest of the asteroid, and we can use the fact that sunlight has momentum to push the asteroid using sunlight!

The MRN size distribution

The most popular interstellar dust size-distribution used by astrophysicists is one due to Mathis, Rumpl and Nordsieck (MRN), which they published in 1977. It suggests that the number of dust grains of various sizes follows the following distribution – n(a) = n_{0}a^{-3.5} where n_{0} is the number at some size a_{0}. So, for example, if you want to compare the number of dust grains which have a size of 1mm compared to the number which have a size of 5mm then the ratio is \frac{1}{5}^{-3.5} = 280 or that 1mm sized dust grains are 280 times more numerous than 5mm sized dust grains. It is unlikely that the distribution of lumps of rock follows exactly the same size distribution, but if it did the number of 15m lumps compared to 50m lumps would be \frac{15}{50}^{-3.5} = 68, so 68 times more 15m lumps than 50m lumps.

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