365daysDate: May 14, 2009

Title: A Tour of Sydney Observatory


Podcaster: The Skeptic Zone Podcast


Description: A tour of Sydney Observatory with reporter Tiffany Day and Geoff Wyatt, the Senior Astronomy Educator. We learn about the history and research of the Observatory.

Bio: The Skeptic Zone Podcast – The Podcast from Australia for Science and Reason, produced by Richard Saunders is Australia’s leading skeptical podcast with reports from around the world.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by AAVSO.


Hi – This is Tiffany Day from Sydney Australia. I’m a first year astronomy student at Macquarie University and also a reporter for the Skeptic Zone Podcast.

Those of you who have visited Sydney may have familiar with the Rocks area, the oldest part of the city build largely with convict labour. But did you know, just above the Rocks, up on Gallows Hill sits Sydney’s Observatory?

On a fine warm day in January, I visited the Observatory and spoke to Geoff Wyatt, the Senior Astronomy Educator.

Ok, I think the important thing to appreciate is, at the moment, outside it’s 30-odd degrees. It’s a brilliant, blue sunny day. But we are standing underneath 3,000 stars in what we call our “Beanbag Planetarium” and we use this as part of our day and our night education programs. This is probably the only planetarium in the world that has beanbags for seats, so everyone probably wonders what happened to them in the 1970s. Like elephant’s graveyards, well, they all came here. Plus we have a fireplace – how many planetaria have a fireplace in them? Probably none, other than us.

Now, could you tell us a bit, Geoff, about the history of the Sydney Observatory?

Ok, well I can only really address the – if you like – the European History of the last 200 years. But, basically what happened is the first building built on this hill was a windmill. The sails, however, were made of canvas. Canvas was a very expensive and sought-after building supply. So it was stolen by the locals. So, a windmill without sails is pretty-well useless.

(laughs) Yes.

So that fell into disrepair quite quickly. The next building that was built here from 1804 to 1806 was Fort Phillip. And that was a citadel intended to be the last bastion – if you like – for the garrison to retreat to in the event of an Irish uprising by the convicts. Now, there actually was an uprising at Castle Hill about three weeks after they started building this Fort, so they never actually completed it. So they stopped building that. And then in the 1840s – I think it was – they erected large flagstaffs, one of which has recently been re-erected outside, to communicate by flags to South Head and Pennant Hills so that signals could be sent around for when ships sailed in the harbor. Then in 1858, this magnificent observatory was built. So we’re 151 years old this year. We ceased to be a research observatory in 1982, and we became part of the Powerhouse Museum, or the Museum of Applied Arts and Sciences. Since then we’ve become – if you like – an astronomical museum.

What important research has gone on here in the past?

There has been a couple of things that have happened. One of our most famous astronomers, Henry Chamberlain Russell, was one of the first people ever to take photographs of the Moon through a telescope. So, we did a lot of work in astrophotography – if you like – meteorology. Russell completed the first ever weather map for Australia.

We became the birthplace of the Bureau of Meteorology. But, most importantly, the Observatory’s prime task – if you like – was to measure the positions of stars to then calculate the time and communicate the time to not only the ships in the harbor, but the fledgling colony. And one of the main pieces of research, or one of our main claims to fame, was the 1874 transit of Venus. When Cook left Portsmouth in 1768 he had sealed orders. And those sealed orders were, of course, he had to go to King George’s Island (Tahiti), observe the transit of Venus where Venus appears to move across the disc of the Sun. Then open his sealed orders which said go and look for the Great Southern Land. So it was after that transit that he actually came this direction looking for Australia and claimed it on behalf of the English.

Now, transits of Venus are very, very important. They were predicted. We knew – if you like – the ratio of the distances of the planets from the Sun but we didn’t know the exact distances. So, for example, we knew that Mercury was only one-third of the distance from the Sun than us. We knew that Venus was two-thirds, and so on, using Kepler’s Laws. But we didn’t know any of the distances. What they figured out is, if you did some very accurate recordings of observations in timing of something like the transit of Venus as seen from Tahiti and from, say, London, with trigonometry you could work out the distance from the Earth to the Sun. And then – whammo! – the whole Solar System, as it was then, falls into place.

Now, they weren’t able to get an accurate enough measurement in 1769. These transits come in pairs just over 100 years apart. So, the next one after 1769 was 1874. And our main telescope in the South Dome was ordered to be here in time for the 1874 transit of Venus. So, we did a lot of observations. We trained astronomers to go out and watch it from places like Woodford in the Blue Mountains, Goulburn, Eden – all over the place – to get an accurate observation of the planet Venus moving in front of the Sun. They weren’t able to do it accurately enough to get the measurements. The next one in the early 1880s, it rained. And then we had the last one which we were actually able to photograph and we won an award for it, Sydney Observatory, was in 2004. And there’s another one coming up in June 2012. If you miss the next one in 2012 no living human will see the one after. So it’s really important for our history and astronomy.

Ok, we’ve just climbed to the top of the building and, Geoff?

Well, we’re in what we very cleverly call the South Dome. What we have here is the oldest working telescope in Australia. It’s a 29 centimeter refractor. The optics come from Germany, and the tube and the mounting was made locally.

Ok, Jeff’s just about to open the Dome for us now.

Now, ok, the dome is almost pointing due East – not quite. But if I move it ever so fractionally you can see why in 1874 we had to build a second Dome. Because if you look out the window, what do you see?

There’s a big building there.

Ooops! That was built one story higher than it should have been by mistake.

Oh no! (laughs)

Alright, we’ve just come outside. We’re in the main garden of the Sydney Observatory now. It’s a beautifully warm, sunny day. I don’t know if you can hear the cicadas, but they’re surrounding us. It’s quite a nice out here. Geoff?

Yeah, actually – just to give you an idea – we can tell what temperature it is by looking at our newly-erected flagstaff. The flags on the Northern yard actually tell us today’s maximum temperature. The other flags tell us the phase of the Moon, which planets are visible, and which constellations are visible. That makes us, as far as we know, the only place in the world to fly a combination of state, astronomical, and meteorological flags. So, looking at the flags, I think I can see 28 is the maximum temperature here in Sydney today.

But what we’re doing, if we look back over here towards the main building, you can see a magnificent example of Italian – Florentine, I think it is – architecture. Architecture’s not my big field, but I believe it’s Italian Renaissance – that’s it – architecture built in 1858. If you look carefully you can see from the time-ball tower across to your right all the windows are rectangular. Across to the left they’re dome-shaped. And that delineates the right-hand side, or the Eastern side, of the building was the astronomers’ residence. And the left-hand side, the Western side, was the working part of the building.

But the main thing is from right here we can actually clearly see the original Dome, which as I mentioned a minute ago, is the South Dome. When the place was being built the Government Astronomer, Reverend Scott, was not always here. The architect and the builders thought that the whole place would look a much better with that typical A-4 relationship if they added one tower to that time-ball tower. Seems like a great idea – it looks good – but of course that means the South Dome cannot see to the East. So we were blind to the East and of course, as a result, if you step over this way just a meter or two, you can actually see our North Dome which we built in 1877. And that gave us a view towards the East as well. So we have two Domes – North Dome, South Dome – and they now work out really well because they give us how Astronomy has changed – a state-of-the-art telescope from 1874 and a present, modern-day telescope in the North Dome.

Well, this has been an amazing trip! Thanks very much, Geoff. Now how can our listeners get more information about Sydney Observatory?

Ok, the best way is via our website which is

Thank you very much, Geoff. Thank you for your time.

You’re welcome.

So, next time you’re in Sydney, why not visit the Observatory. The views overlooking the harbour and the city are breathtaking.

Thanks to Richard Saunders and Crystal Foster for their help with this segment.
This has been Tiffany Day from the Skeptic Zone Podcast at

End of podcast:

365 Days of Astronomy
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