QI Tour - Siding Springs Observatory (Day 17)

The size of big dome building
becomes obvious in scale to
the cars parked in front.

Siding Springs Observatory is located on Mount Woorut, 1164 metres above sea level and high above the eastern end of Warrumbungle NP. Operated by the Australian National University in Canberra, it is currently in its 60th year of service.

There are a number of telescopes at the location, ideally situated beside what is referred to as a Dark Sky Park - meaning the level of light interference is minimal. The grandfather of them all is the Anglo Australian Telescope, with its 4 metre mirror and located under the "big dome" which is 7 storeys high and weighs over 500 tonnes. It was officially opened by then Prince Charles in 1974 and will be celebrating it 50th year of operations with a special series of events and open days in October. The stats surrounding the telescope are staggering and I won't attempt to burden you with them but suffice to say, the achievements in astronomy obtained at Siding Springs have been world leading. The first movement software for tracking celestial bodies was developed by technician Bob Dean and astronomer David Milan has among his many accomplishments a reputation for being one of the best photographers of space objects. 

The telescopes are each named for the diameter of the mirror at their base because as brilliant as astronomers are, it doesn’t extend to creativity in nomenclature. Our guide calls it Frank.  

The 4m telescope

Dean is renowned not only for his technical brilliance but also for his sense of humour: a quality not always appreciated by the scientists who have worked here, because at the core of his mirth is a wicked dedication to practical jokes. On one occasion, with an astronomer working high up in the very top of the big telescope - a procedure now banned for occ/health and safety reasons - Dean inflated a helium balloon inside the dome, which floated inevitably up to the top of the structure and became lodged in the end of the telescope, repeatedly hitting the astronomer. The fact it had a devil with horns painted on it and it was of course in the middle of the night, created five minute of screams ... and very little laughter. The same Dean created a warning program to provided audible alarms when the telescope was being maneuvered beyond its specification and therefore endangering the fragile mirror at it heart. It would cost $50 million to replace it if it was broken or damaged. Dean chose to use the sound of shattering glass as the audible warning and the first time it sounded, considerable distress was experienced by the operator!

Of course, it is impossible to tell the story of Siding Springs without mention of the terrible fire which raged through Warrunbungle NP and surrounds in 2013. The fire rose up from the valley on the southern side and licked at the big dome, being saved by water bombing and a special water tower which had been installed 40 years earlier with the express task of spilling its contents and flooding the area to extinguish or at least control fires. Unbelievably, the operating valve had never been tested since installing and even more incredible, it worked first time! Inside the dome, designed to block out surrounding conditions, the temperature rose only a few degrees despite the conflagration on the other side of its walls, with flames extending at one stage 30 metres above the height of the dome. The irony above all others was that when the fire was able to crest the mountain, it missed the dome and only destroyed two buildings, one of which normally housed the fire fighting truck and equipment. 

Our guide for the afternoon was very impressive. His mix of clearly explained information and facts was littered with funny anecdotes and it made for a very entertaining 90 minutes. 

View to the north

The highlight of the event was a visit to the gantry high up on the large dome building, circumnavigating it at the junction of the vertical wall and the dome section. The views were staggering in their 360 degree magnificence and owing to the clear viewing conditions, we could see to the horizon in any direction. Tambar Mountain could clearly be seen, 60 kms to the east and the inverted cones which lie near Mullaley were also obvious. The views over Warrumbungle NP underlined again how stark its geology is and made it even easier to imagine the 50km wide shield volcano that was the origin of the amazing mountain formations. The oft made statement that the park marks the point where the western plains of NSW start was obvious but it was the view to the north which captured our attention because its one you can't see normally. 

We learned an interesting way of determining relative heights. When viewing a mountain peak from a height, if the peak appears to be above the line of the horizon then it is taller than where you are. If it is below, then it is shorter. I’m not sure I think this is accurate.

Back on the fourth floor of the building, a visitors gallery provides lots of information about the Observatory and includes the centre section of the mirror which was removed to accommodate equipment. The once a year process for ensuring it maintains high reflectivity involves cleaning the coating of aluminium from the surface and reapplying it. Surprisingly, the amount of aluminium it takes to coat the mirror is about the equivalent of a soft drink can! 

The model of the
4m mirror

Outside the dome and overlooking the national park, is a life sized model of the mirror and the actual case it was transported in from the UK. The final part of the trip was taken on the back of a flatbed semi. It took over three hours to ascend to the top of Mount Woorut from the Timor Road below. Not surprising when you experience the narrow and steep transition from one to the other as you drive up to the summi.

Beside the model is one of those brass dials with the direction and distance to major cities and landforms. It was made in Canberra. Ironically, the maker misspelled the name of his own city!

We started and finished our visit in the cafe situated at the Observatory. Good coffee, lots of merch choices at reasonable prices and friendly service.

In a final treat, after all had left and the facility was being closed for the day, we got to watch the dome being rotated into position from the car park!

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today's photos

This was one of the activities that come as surprises in our travels. It was certainly one of the best activities we have done.

Returning to camp, the lack of wind allowed us to have a campfire, over which we cooked steaks and boiled the billy, rounding out a really pleasant day.