Light trespass of 'spilled' light is the result of light that does not reach its destination, or is reflected having reached its destination or is scattered by the media between the source and destination. Astronomers - both professional and amateur astronomers - are often severely restricted in their observations as a result of light trespass (sky glow). Only a few sites on earth are left that are 'clean' enough for serious high-accuracy measurements. Space astronomy cannot replace earth-bound observations. Several remedies to reduce the light trespass are known and are applied on a limited scale such as the application of low-pressure sodium lamps and the use of careful light control. Residents suffer particularly from light trespass in their bedrooms. On the basis of preliminary measurements it seems that the discomfort is acceptable if the illuminance is less than 3 lux on the plane of the bedroom window. In order to combat light trespass, further research is needed, further consideration of the matter within the lighting profession is required and liaison with other interest groups should be maintained or, preferably, be improved. In all three areas, CIE obviously has a role to play. (Author/publisher)
Abstract