Evening Zodiacal Light

From the UK the Zodiacal Light is visible in the early evening for the first three months of the year. Apart from weather and light pollution the variations in sky transparency can make a big difference to the visibility of this low surface brightness feature. Even small towns 10 miles away can be a nuisance by making it difficult to distinguish their arch of light pollution from the glow of Zodiacal Light.

The camera records the colour difference between reflected sunlight and the light pollution, however this isn't obvious to the eye so it is shape and position which are important. With a broad low surface brightness feature like this the trick is to sweep your eyes across a wide area of sky. That way the contrast between Zodiacal Light and the darker background on each side shows up more clearly.

The images below were all taken from mid-Wiltshire on a Canon 20D, set to 30 seconds at ASA 1600 and using a Sigma 10mm lens at f4. (Original jpegs reduced in size for the web but otherwise unprocessed)

Only a month past the winter solstice and the ecliptic is already at a steep enough angle for the Zodiacal Light to clear the lower level haze.

The crescent moon is about to set, followed by Jupiter. The faint cone of Zodiacal Light stretches from them up to the left at about 45 degrees.

18:48 UT on 17th January 2010.
Sun 20.8 degrees below horizon.

Just before the end of astronomical twilight the sky is dark enough and more of the cone is visible.

Unfortunately the brightest part is completely obscured by light pollution.

18:43 UT on 1st February 2010.
Sun 16.9 degrees below horizon.

(Astronomical twilight ends with the Sun 18 degrees below the horizon)

The sky only cleared after the end of twilight so this was taken later than I would have liked, losing 5 degrees of the brighter part of the glow.

The ecliptic is now at a steeper angle, and is gradually moving to the right as spring approaches.

19:42 UT on 14th February 2010.
Sun 22.7 degrees below horizon.

A fairly transparent night allowed the Zodiacal Light to show up despite the skyglow to the west.

The northward movement and increasing steepness of the ecliptic is now quite clear after 6 weeks.

19:39 UT on 4th March 2010.
Sun 17.5 degrees below horizon.

The Pleiades are now in the Zodiacal Light and it won't be long before the Milky Way starts to interfere.

19:56 UT on 14th March 2010.
Sun 16.7 degrees below horizon.

Top end of zodiacal light in Milky Way and brighter parts in light pollution plus the last hint of twilight. It needs a bit of averted imagination to see anything now!

20:33 UT on 7th April 2010.
Sun 15.6 degrees below horizon.

Taken at the end of astronomical twilight. Zodiacal light is barely detectable, even the thin part of the Milky Way spoils the contrast.

21:13 UT on 16th April 2010.
Sun 17.9 degrees below horizon.

Wiltshire, England

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