BAA CfDS / CPRE Christmas and New Year Star Count: the Clean Sky project.
Please note, the January Star Count has now completed. Observations can no longer be submitted via the website.
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Light pollution from poorly directed and over-bright lamps is present in the starry sky almost everywhere in the UK, and has steadily increased since the 1950s. The CPRE's 'Night Blight' initiative in 2003 and ongoing campaigns drew attention to this, and the British Astronomical Association's Campaign for Dark Skies (CfDS) works continuously to publicise and alleviate the problem.
Together we’ve organised a simple star count. People everywhere in the UK can take part in during the nights running up to Christmas. Its aim is to help us gauge the extent of light pollution, and to raise awareness about the issue. If enough people take part, we hope to repeat the experiment in future to try to assess any trends.
You can view this slide show which shows how many stars you might see, depending on how much light pollution there is around you and how hazy the atmosphere is.
If you would like to contribute to the Clean Sky project, this is all you have to do: |
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1. If the sky is clear, without obvious haze, on any of the nights between December 20-24 2006, find the constellation of Orion (see the photo above), to the southeast* between 20:00 GMT and 24:00 GMT (we are now on GMT). (Look north, too, on these nights and you may see occasional meteors, shooting stars, of the Ursid meteor stream, which reaches its peak at this time of year.)
2. The main area of the constellation is bordered by a rectangle of four bright stars (Orion's 'shoulders' and 'feet'), as marked in red on the photo when you place your mouse over the picture above.
3. Count the number of stars you see with the naked eye within this rectangle (including Orion's three-star 'Belt', but NOT including the four 'corner' stars mentioned above), with spectacles or contact lenses if worn. Even in the most light polluted areas you should be able to count a few stars. But in those places with very little light pollution, you’ll be able to count many.
4. Submit your result as soon as possible after you observe, via the internet using the on-line form, or by post to Clean Sky, CfDS, 38 The Vineries, Colehill, Wimborne BH21 2PX. Please give your postcode. Note observations are no longer being taken.
5. We’ve chosen the five nights of December 20 - 24 because the moon will be at its smallest then, so its light will not obscure many stars. But if clouds prevented you from observing Orion then, wait until the Moon-free period in the middle of January, and try again on any night between January 14 and January 21.
6. Please visit the websites of the BAA Campaign for Dark Skies and the CPRE's Light Pollution Campaign for more information about the problems of and solutions to Light Pollution in the UK.
Observing Hints
- Do the star count before you imbibe in Christmas cheer
- Observe away from lights where possible
- Give your eyes about 10 minutes to adapt to the dark
*If you are not sure where south is in the sky, Orion has such a distinctive shape that you will probably find it easily. For those with extremely light-polluted skies and no compass, south is the direction in which TV satellite dishes point - or where the Sun is at midday (but NEVER look directly at the Sun!). Remember that, if you are looking south, east is to your left.
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