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Light Pollution & the AONB Dark Sky Reserve

Updated: Oct 18, 2022

Chasing Stars - Cranborne Chase International Dark Sky Reserve

Did you know that 90% of the UK’s population and two-thirds of the world’s population live under heavily polluted night skies?

We think of pollution in terms of dirty air, water contamination and excessive noise, all of which can have a significant impact on us. However, light pollution is equally a problem and is already having a big impact on our health. It is also affecting local biodiversity, particularly insects, birds and trees.

Here at Cranborne Chase, though, we are lucky to possess and cherish our dark night skies. Ours is a unique area of pristine night skies where, on a clear night, fortunate residents and visitors can witness the majestic arc of the Milky Way.

" Running a B&B, we get lots of guests from the cities, and they all comment on how beautiful the night skies are. Many sit in the garden into the small hours looking at the stars! "

This is one of the most treasured qualities of the AONB and we are working with other UK Dark Sky Places to get our dark night skies the statutory protection they need to enable them to thrive and survive. We were the first AONB to became an International Dark Sky Reserve in its entirety, but we want to make our dark skies even darker.

The Right Light at Night

In October 2019, Cranborne Chase AONB became only the 14th International Dark Sky Reserve (IDSR) worldwide (there are now only 17). This prestigious status was awarded in recognition of the exceptional character of our dark skies in particular, and nocturnal environment in general.

Right Light, Right Place, Right Time

We need artificial light at night for safety, for work, and for leisure, but nature needs the night, so how do we balance our needs and those of the nocturnal environment? The principles of responsible outdoor lighting are encapsulated in the phrase Right Light, Right Place, Right Time.

The Right Light is a softer “warm white” light of the minimum necessary brightness, which does not create glare or dark shadows that conceal what it should reveal.

Right Place is simply to use careful aiming and shielding to direct the light to where it is needed and ensure that it does not intrude where it is neither wanted nor needed, especially upward into the sky.

Right Time is when it will actually be useful, and this can be achieved by using timers or PIR motion detectors.

'On-all-night' security lighting often merely acts as a beacon to advertise that there is something valuable nearby.

If you drive, you will have noticed that you need to wipe far fewer insects off your windscreen than even 5 years ago. You may also have noticed that you have far fewer moths and insects coming into a lit room if you leave a window open. These two reveal the long-term effects of the wrong sort of light: harsh, cold, bright white “blue rich” light. This has been devastating for nocturnal wildlife: amongst other harms, it is a direct driver of the “insectageddon” component of the biodiversity collapse.

We are on course to lose 30% of our remaining insect populations in the next 20 years. The American Medical Association has already declared light pollution to be a health risk because of its adverse effects on human health.

Is your property Dark Sky friendly?

You can use this handy flowchart to check if your outside lighting is dark sky friendly:

Cranborne Chase AONB has funding available to support the movement towards Dark Night Sky friendly light fittings, both domestically and specifically for farmers and land managers through the Farming in Protected Landscapes programme, running until March 2024.

For more details contact the AONB’s Dark Skies Adviser:

Further information:




This Charter sets out the principles to be followed by any organisation or individual who signs up for the Dark Sky Friendly Scheme. It will be a fundamental document for initiating and coordinating action related to our status as an International Dark Sky Reserve.

In 2019 the International Dark-Sky Association granted us the prestigious designation of International Dark Sky Reserve (IDSR). As part of the conditions of this designation, we must reduce light pollution in the night sky above the IDSR. Those who sign up to this Charter value the quality of the dark sky that already exists and undertake to act to preserve and enhance this quality. Signatories will implement and/or promote the following:

  • Shielding lights, so that they do not emit any light above the horizontal, to reduce skyglow and the adverse effects of light on flying fauna.

  • Shielding lights, so that they do not shine off the property, to reduce light intrusion and glare.

  • Using light of a correlated colour temperature of 2700K or lower (“warm white” light) to reduce glare, skyglow from light scatter, and the adverse effects of light on nocturnal fauna.

  • Have exterior lights on motion sensors (PIRs) with a maximum “on” time of 5 minutes to reduce their effect on all aspects of the night-time environment, especially skyglow from light scatter and reflection, and the adverse effects on flora and nocturnal fauna.

  • Using lights with the minimum brightness necessary for their intended task to reduce their effect on all aspects of the night-time environment, especially skyglow from light scatter and reflection, and the adverse effects on flora and nocturnal fauna.

  • In the case of tourist accommodation providers, promote the dark sky environment by providing binoculars or telescopes, star charts, red-light torches, etc., for loan to guests, and making provision for late returns in the night after astronomy activities, and late breakfasts.

  • Respect and raise awareness of the IDSR generally by promoting, in person, on social media, or on own websites, dark sky events such as stargazing evenings and talks on light pollution and its consequences and remedies.


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