Zodiacal Light

Untold interplanetary dust particles scatter the sun's light to form a soft cone stretching upwards towards the Pleiades and Jupiter. Orion is at left. Imaged by Monika Landy-Gyebnar at Tihany, Hungary   ©Monika Landy-Gyebnar.
Atmospheric
Optics
About - Submit Optics Picture of the Day Galleries Previous Next Today Subscribe to Features on RSS Feed
         

"The horizon was a bit bright with last efforts of twilight ruling the sky when zodiacal light began to appear about 1,5 hour after sunset. Soon the light cone became very bright despite the nearby (~ 50 meters) streetlights behind me. It was the brightest appearance of zodiacal light I have ever seen. It lasted about an hour and then it slowly faded." More pictures.

Lore has it that the Zodiacal Light is seen easily only in the tropics. It is best seen in the tropics but it is visible almost anywhere if it is searched for at the right time and you know where to look. It is much larger than it appears in photographs, get away from direct lights and start by using averted vision an hour after sunset - a faint and ghostly cone will then appear.

March is a good time in the Northern Hemisphere because the ecliptic (marking the plane of the solar system) makes a steep angle to the horizon.

A disk of dust out to the orbit of Jupiter and perhaps beyond produces it. The dust grains are 0.001 to 0.3 mm across and likely originate from comets.  

The dust grains are large compared to the wavelengths of visible light and consequently scatter sunlight strongly forwards. The glow is therefore brightest near to the sun.