Once again the Campaign to Protect Rural England and the British Astronomical Association’s Campaign for Dark Skies are running a UK-wide star count programme. This year’s event takes place between 20-27 January 2012. On any of these nights the skies will be dark enough to begin your star count by 7pm.
To make your own observations for Star Count 2012 find Orion in the sky and count how many stars you can see within the rectangular boundary formed by the four brightest stars in Orion. Those boundary stars are called Betelgeuse, Bellatrix, Rigel and Saiph.
You should count the three belt stars – Alnitak, Alnilam, and Mintaka – plus any other stars that are visible. The above star map shows around 40 stars within that boundary. If you can see that many stars then you’ll be in one of the darkest places in the UK. For most of us we’ll count far fewer stars than that. People in very bright urban areas may only see the three belt stars.
UPDATE: I should have mentioned that the CPRE will accept observations from anywhere in the UK, not just England.
Star Count Week (Monday 31 January – Sunday 06 February 2011) aims to get you outside and looking up, specifically to assess how dark – or light – your sky is.
The technique is simple. 1. Find Orion. 2. Count all the stars you can see within the main rectangle formed by Betelgeuse, Bellatrix, Rigel and Saiph, the four stars that make up Orion’s shoulders and feet. (including the three bright belt stars). 3. Tell the CPRE.
That’s it. By counting how many you can see, astronomers can calculate your sky’s limiting magnitude, or the brightness of the faintest stars you can see. It’s a very simple – and rewarding – project to take part in.
There are other annual star count programmes, such as GLOBE at Night (March 22 – April 4 2011) which I blogged about during their 2010 event. You can also get more involved and conduct a detailed dark sky survey, or take part in local activities such as the Peak District National Park’s Orion in the Peak project
The Peak District National Park (PDNP) have recently announced an excellent public engagement light pollution project, Orion in the Peak.
I first contacted PDNP in early 2008, in my role as UK Co-ordinator for IYA2009, as part of my efforts to encourage UK parks to consider working towards becoming a Dark Sky Place, through the International Dark-sky Association’s programme.
In the end it was Galloway Forest Park that was first to become a Dark Sky Park (the UK’s first), but PDNP and Exmoor NP are working hard to gather the data they need to submit an application.
The Peak District was the UK’s first national park, formed in 1952, and is also the UK’s busiest, with an estimated 22 million people visiting each year (this makes it the world’s second most visited national park, after Mount Fuji National Park in Japan). This is due to the Peak District’s proximity to so many large cities, with Manchester and Liverpool in the west, Leeds in the north, Sheffield in the east, and Birmingham to the south. This means that the park’s skies are not free from light pollution – not by any means.
However the IDA knows that there is value in recognising such skies, alongside the perfectly dark skies of Utah and Galloway. Their criteria is that a park has an “exceptional dark sky resource relative to the population is serves“, and the Peak District serves a very large population indeed: 25 million people within 2 hours drive, and 60 million within 4 hours drive (virtually the whole of England and Wales, and Scotland as far north as the Central Belt).
The Macclesfield Astronomical Society have been working with PDNP on their dark sky surveys, and now it’s the public’s turn!
To encourage local residents to get involved in preserving their night skies the Peak District National Park has announced their Orion in the Peak project:
The Peak District National Park is lived in and visited by many and is an area of the countryside that currently has some dark skies. We are working with others to ensure that our special landscapes and skies are there for future generations to enjoy. We are looking to pursue international recognition from the International Dark Sky Association for the quality of the National Park’s night skies, and we need your help.
They are asking members of the public to:
measure the darkness of the night sky between 31 December 2010 and 5 January 2011, or between 28 January and 2 February 2011. Using this information we will be able to produce a map of night sky quality in the Peak District National Park. The darkness of the night sky can be measured by comparing how the constellation of Orion (the Hunter) appears where you are to a set of sky quality charts, and then letting us know via this website.
They have produced a full set of instructions, available here (pdf).
Tonight is a symbolic and poignant one for me here in Glasgow; tonight Orion’s right foot Rigel sets at 2232, by which point astronomical twilight won’t even have ended.
This means that Orion is setting into the glow of the Sun in the west, and very soon won’t be visible at all. By the end of April Orion will be setting by 2100, only minutes after the Sun, so will be invisible until it appears next winter.
These dates will differ somewhat for you depending on where you are: if you’re further north than Glasgow Orion will already have begun to vanish in the longer days, and if you’re further south it will linger a bit, but to all intents and purposes that’s it for Orion till winter.
So take the opportunity to go and see Orion the Hunter while you can, before he vanishes into the glare of the Sun.
Had a great day yesterday filming with the BBC. We started out in GSC‘s planetarium, filming for a couple of hours as I “tought” the presenter Katie Knapman how to find her way around the sky. Filming in the planetarium was tricky, but the cameraman Rob’s normal job is filming the Sky at Night, so he was an dab hand.
The presenter was very enthusiastic, either genuinely so or good at faking it. After two and a half hours we were ready to head off to Galloway Forest Dark Sky Park. I always enjoy the drive south, but the prospect of a very clear sky made me more excited than normal.
Stepping out of the car at Clatteringshaws Loch car park, I was greeted by a stunning view of thousands of stars overhead. The sky was more or less cloudless, but the local landowners had been burning back the heather all day, and so a faint haze of smoke make everything a little bit less dark and clear than it might have been.
We had to wait for half an hour or so until the end of astronomical twilight in order to get a properly dark sky, so in the meantine, and as the film crew faffed about with their equipment, I shot a few pics of the night sky. It was the first time that I’de ever used my DSLR Nikon D50 and my new tripod to image the night sky, so I only got a few good pics (see above).
Best of all though, the International Space Station was due to pass overhead again, and this time I was prepared for it. On cue it began increasing in brightness, heading towards Orion from the west. I took a two minute exposure of the ISS moving through Taurus and Orion, which turned out rather well, with the exception that the stars are a bit blurry as a result of the Earth’s (and my camera’s) rotation.
Just finished filming the first of two evenings for BBC’s Countryfile programme. This evening was just some footage of me taking Sky Quality Metre readings in a brightly lit urban environment; in fact just outside the BBC Scotland building and Glasgow Science Centre.
It was, amazingly, a clear night, but even with no clouds we could only make out a few dozen stars through the glare of the local lights and the glow of the light pollution from the whole of Glasgow. If you’re interested, the SQM read 17 or so.
I set my DSLR camera up to take some pics of the filming, just for posterity, and in between I took some scenic shots of the viscinity, like this nice one of GSC and Glasgow Tower, showing the skyglow.
The best part of the night though, by far, was seeing the ISS flare up towards the WSW and having just enough time to set my camera up to capture this shot of it passing through Orion! Didn’t have enought time to figure out exposure times to get the best possible shot, but still, my first attempt at astrophotography paid off big time!
Off home now, chuffed with my pic, and looking forward to tomorrow night’s filming in Glasgow Planetarium and then later in Galloway Dark Sky Park.
For the first time since this year’s GLOBE at Night started I have a clear sky, so I popped out into my back garden to find Orion and measure how light polluted my sky is.
I live in Glasgow, on the south of the city, in an area that is probably fairly described as being on the urban / suburban interface, so my sky isn’t great, even when clear. That coupled with regular cloud cover and tall trees to the south mean that my garden is far from ideal for stargazing. Even still, the small patch of sky visible to me never fails to impress on a clear night, even through the light pollution. At this time of year (late spring) Orion sits nicely in the space between the nearest buildings and the trees.
And tonight is no exception. Orion is standing proudly overhead, and using the GLOBE at Night star maps I could make out that my sky is magnitude four. Not bad, but not great. There are probably two or three times as many stars visible here as would be seen in the city centre of Glasgow, but go out into a truly dark site, such as Galloway Dark Sky Park, and you’ll see ten times as many again.
Sky Quality Metre
Using my nifty little Sky Quality Metre I can get a much more accurate measure of how bright my sky is. The metre gives a reading of magnitudes per square arcsecond (i.e. brightness per unit area in the sky). The readings, if taken of the zenith point directly overhead, range from around 16 in a bright city up to 23 in a very dark place indeed (Galloway Dark Sky Park, at the darkest part, registers 22.7 magnitudes per square arcsecond). The sky above my garden at the moment is reading 18.3, which is much better than I expected. I must get my telescope out before summer arrives…