The Brecon Beacons National Park has become the fifth location in the world - and the first in Wales - to be granted International Dark Sky Reserve status, which protects the quality of star-gazing in the area.
It follows an application from the Brecon Beacons Park Society and the National Park Authority
The status officially recognises the nocturnal environment in the area - with low levels of light pollution.
Information leaflets and letters were distributed to residents living in the area to help them understand the measures they could take to keep the skies dark, such as tilting outdoor security lights downwards instead of up.
The area joins four other certified Dark Sky Reserves throughout the world - Mont Mégantic, Quebec, Canada; the Exmoor National Park in south-west England; Aoraki Mackenzie, New Zealand and the NamibRand Nature Reserve, Namibia.
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There will be some patchy rain but many areas will be dry for much of the time.