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.
reach: rather globalastronomyskyspaceunits
Answers by country
spectrum of the stars
types of nebulae
brightness of the night sky
size of the planets
answers
Switzerland
20
France
16
the United States
148
Australia
37
South Africa
12
Austria
58
the Philippines
24
Estonia
11
Pakistan
17
Germany
321
Canada
22
the United Kingdom
100
India
295
Poland
4606
Republic of Ireland
20
the Netherlands
10