Night sky night sky. Aircraft are also visible at night, distinguishable at a distance from other objects because their lights blink. Night sky The term night sky, usually associated with astronomy from Earth, refers to the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a night sky include moonlight, starlight, and airglow, depending on location and timing. Aurorae light up the skies above the polar circles. Occasionally, a large coronal mass ejection from the Sun or simply
Northern lights chord Northern lights chord In music, the 'northern lights' chord is an eleven-note chord from Ernst Krenek's "Cantata for Wartime" (1943), that represents the Northern Lights. Krenek's student, Robert Erickson, cites the chord as an example of a texture arranged so as to, "closely approach the single-object status of fused-ensemble timbres, for example, the beautiful 'northern lights'...chord, in a very interesting distribution of pitches, produces a fused sound supported by a suspended cymbal roll". "The 'northern lights' sounds, so icy and impersonal and menacing, are a brilliant orchestral invention." At eleven-notes the chord is one pitch shy of the total chromatic.