What does the Bortle scale refer to?
spectrum of the stars
types of nebulae
brightness of the night sky
size of the planets
The Bortle scale is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution. It was created by John E. Bortle in 2001.
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Answers by country
spectrum of the stars
types of nebulae
brightness of the night sky
size of the planets
answers
France16
Switzerland21
the United States159
South Africa13
Australia39
Austria58
the Philippines24
Estonia11
Pakistan17
Germany336
the United Kingdom108
Canada22
India295
the Netherlands12
Poland4753
Republic of Ireland20