December 7, 2012 – The Amazing Sky

From a truly dark sky site, subtle sky glows become obvious. This is the Zodiacal Light of evening.

The Sun has long set and the very last glow of twilight is colouring the sky just above the hills. But reaching up from the sunset point in the northwest is a long triangular glow extending far to the south. This is called the Zodiacal Light – it does not originate in our atmosphere but is from sunlight reflecting off comet dust orbiting the inner solar system in the same plane as Earth’s orbit. Or at least that’s where we see it appearing the brightest, as a glow brightest near the Sun and extending along the ecliptic plane, where we find the constellations of the Zodiac. Here it appears in Capricornus and Aquarius.

I shot this two nights ago, from Coonabarabran, Australia, so the orientation of the Zodiacal Light is different from what we see from the Northern Hemisphere. Here it extends up from left to right. From home in Canada – and you can see the Light from northern latitudes on a dark night – it would be angled up from right to left, a mirror image of what we see here.

The subtle glow of Zodiacal Light is best seen in the evening sky in spring, no matter your hemisphere. I took this on December 6, 2012, still officially spring in the southern hemisphere if you assume southern summer starts on the solstice, December 21. However, Australians say summer begins December 1, so this is a portrait of the Zodiacal Light on a warm summer evening down under.

On Friday I had the pleasure and privilege of giving a talk at “The Dish.”

This is the Parkes Radio Telescope, a big 64-metre diameter dish antenna used to explore the radio sky. To the public it is famous for starring in the Australian movie, The Dish, that told the story, somewhat accurately but with liberal license throughout, of how the The Dish was used to receive the first TV signals from the Apollo 11 moon landing in 1969.

Next week The Dish celebrates an important anniversary, 50 years since December 14, 1962 when Parkes received the signals from the first successful interplanetary probe, Mariner 2, flying past Venus, revealing that planet’s hellish conditions for the first time.

While The Dish is called upon occasionally to serve as a ground station for planet probes, its primary mission is to record natural radio signals from deep space objects, notably pulsars, spinning neutron stars. CSIRO’s website presents lots of information on the Parkes telescope.

Last night I presented a talk and picture show about the wonderful sky events in 2012, highlighted by the Great Australian Eclipse, to a nearly full house of local amateur astronomers at the Visitor Centre, where I took this photo. The talk was part of the monthly meeting, open to the public, of the Central West Astronomical Society, a very active club of which I am proud to be an honourary member. Whenever I am in Australia I try to get to Parkes on the club’s meeting night, to give a talk to the group and to meet up again with many of my Australian astronomy friends. It was a great evening. Thank you all!