Meanings
proper nounthe Bortle scale
- astronomyA nine-level numeric scale that measures the night sky's brightness of a particular location.
Origin
Named after John E. Bortle, who created the scale.
Full word history & related roots →Cite this entry
APA
Bortle scale. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/Bortle%20scale
MLA
“Bortle scale.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Bortle%20scale. Accessed November 4, 2026.
Chicago
WatkinsX Dictionary, s.v. “Bortle scale,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/Bortle%20scale.
Source: Bortle scale on Wiktionary, CC BY-SA 4.0.