A False Dawn at KPNO

The western horizon looks especially eye-catching in this image of the Nicholas U. Mayall 4-meter telescope at Kitt Peak National Observatory (KPNO), a Program of NSF’s NOIRLab. Beneath the glittering band of the Milky Way galaxy sprouts a cone of hazy, pastel light known as zodiacal light. This light shines along the ecliptic — the plane of our Solar System and the path of our Sun in the sky — meaning it appears just before dawn breaks or after dusk ends. With its soft white shine, the phenomenon is sometimes referred to as ‘false dawn’ or ‘false dusk’. However, unlike the reddish skies of true dawn and dusk which are caused by Earth’s atmosphere, the zodiacal light originates far beyond our planet: zodiacal light is caused by sunlight reflecting off interplanetary dust lying between the inner planets of our Solar System.