The Subtle Glow of Comet Dust


Zodiacal Light rfrom Home (Feb 8, 2013)

Out of the skyglow from lights and the remains of twilight rises a tapering pyramid of light. It’s one of the night sky’s most subtle sights for the naked eye.

This is the Zodiacal Light, and I’ve been trying to capture it in the evening sky from home for a number of years. Last night was a good night for it. The sky was very transparent, for the first couple of hours at least. An ultra-wide angle lens allowed me to capture the Light in context with the wider sky, towering out of the southwest at right, reaching up to the Pleiades and Jupiter high in the centre of the frame. The Milky Way is at left. Everyone knows the Milky Way but the Zodiacal Light is less famous.

It’s visible only in the hour or two after sunset or before sunrise. Late winter and spring are the best times to see it in the evening sky. That’s when the ecliptic – the plane of the solar system where the planets lie – is tipped up at its highest angle above the horizon putting it above obscuring haze. The Zodiacal Light lies along the ecliptic because it is part of our solar system, not in our atmosphere. It is sunlight reflected off dust orbiting in the inner solar system that’s been cast off over thousands of years by comets passing through. It is brightest closest to the Sun and fades out at greater angles away from the Sun. Thus its tapering appearance in my sky as the photo shows, very much as my eye saw it.

It takes a good night at a dark site to see the Zodiacal Light. But take a look at the next dark of the Moon. You’ll be surprised at how easy it is to see once you know what to look for.

– Alan, February 9, 2013 / © 2013 Alan Dyer

 

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