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DISPLAYING POSTS FROM: May 2012 (13)

Transit of Venus

Author
by Tanya
Publish date
29 May 2012
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On Wednesday 6th June, we have the chance to witness a rare astronomical event - a Transit of Venus. The Earth, Venus and the Sun will fall into line and we will see (with the appropriate equipment) Venus as a small black dot moving across the bright yellow Sun. The first Transit observed was in 1639, and there have only been five since, in the years 1761, 1769, 1874, 1882 and 2004.

"I recommend it therefore again and again to those curious astronomers who (when I am dead) will have an opportunity of observing these things, that they would remember this my admonition, and diligently apply themselves with all their might in making this observation, and I earnestly wish them all imaginable success …."

Edmund Halley, the astronomer made famous by Halley's comet, wrote those words in 1716. He was sixty years old at the time and was well aware that he would not live to see a Transit in his lifetime. But he had discovered that this rare event would unlock the scale of the Solar System and so he urged future astronomers to make good use of his findings and wished them " immortal fame and glory."

You see, back then we knew the relative distances of the planets – Mercury is almost 3 times closer to the Sun than Earth, Saturn is 10 times more distant – but we didn’t know their true distances. The key was the Earth-Sun distance, astronomers call it the Astronomical Unit, and Halley had realised that this could be measured during a Transit of Venus.

Observations of the transit from different locations across the world would differ slightly – some would see Venus travel a short path, moving onto the Sun later and leaving earlier than would be seen elsewhere. By timing the planet's journey and adding in some trigonometry (the mathematics of triangles) the Earth-Sun distance could be measured and everything else would fall into place.

 

Transit from space The path of Venus across the Sun varies slightly when viewed from different locations on Earth. Image is not to scale.
Source: Museum Victoria
 

Astronomers of the 18th Century took up Halley's call but the world was a much bigger place back then. The southern hemisphere was largely unexplored – Captain Cook observed the 1769 transit from Tahiti then went on to undertake the historic mapping of Australia’s east coast.

And no one can forget the tenacious efforts of the French astronomer Guillaume Le Gentil. The Seven Years War was underway and after more than a year of traveling across treacherous seas Le Gentil was unable to reach land in India because it had been taken over by the enemy, in this case the British.

In fact, Le Gentil’s story is heartbreaking. He had brilliant viewing conditions for the 1761 transit, but because he was stuck out at sea with no means of determining his location (ie. longitude) nor an accurate clock for timing the event, his observations didn't mean a thing. What he would have given for a smartphone with GPS!

Amazingly, Le Gentil decided not to go home but to wait out the next 8 years for another Transit. He built an observatory, survived a severe illness, and was fully prepared for the day, only to be beaten by the weather. When he did return to Paris eleven years later, he had been presumed dead – his wife had remarried, his estate was gone and he’d lost his seat at the Royal Academy of Science. Not exactly the fame that Halley had imagined.

Those early astronomers by solving the scale of the Solar System, were also helping us to understand the Sun. By knowing its distance, we could confirm the Sun's size, mass and intrinsic brightness. What’s more, they were also setting us up to determine the extent of the entire Universe. The Earth-Sun distance is the baseline for measuring the distances to nearby stars. A series of stepping stones then takes us distance hopping across the Universe – all the way from star clusters to galaxies near and far.

So next month, when we have the chance to witness the last Transit of Venus for this century, I urge you to heed Halley’s words. It may not be a glitzy show but it’s our connection to both the Universe around us and a piece of our history. And just like those astronomers of the past, we can take a moment to wonder what the world will be like by the time the next Transit rolls around for that far-off December in 2117.

UPDATE: Scienceworks' special Breakfast with Venus from 8am to 10am on Wednesday 6th June is now sold out.  

2004 Transit Venus transiting the Sun in 2004
Image: Hugh Gemmell
Source: Hugh Gemmell

Links:

Transit of Venus

Transit of Venus app for iPhone and Android

Transit of Venus: 1631 to the present by Dr Nick Lomb, published by Sydney Observatory.

Science in the South Seas exhibition at the National Museum of Australia

Reconciliation Week

Author
by Katrina
Publish date
28 May 2012
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National Reconciliation Week runs annually from 27 May to 3 June, marking the anniversaries of two major events that paved the way for the recognition of Aboriginal and Torres Strait Islander rights.

Poster for National Reconciliation Week 2102. Poster for National Reconciliation Week 2102, featuring chefs Stephanie Alexander and Mark Olive.
Source: National Reconciliation Week
 

On 27 May 1967, a Federal referendum gave the Australian population the opportunity to change two key sections within the Australian constitution. The first change ensured that Australia's First People would no longer be excluded from the national census. The second change gave the federal government the power to determine the future for Aboriginal people, taking the power away from individual states and territories.

Overwhelming support for the initiative saw over 90 per cent of the population voting to recognise Aboriginal and Torres Strait Islander people in the census. However, the changes to the constitution did not grant Aboriginal people the right to vote, as has commonly been stated. Aboriginal people became Australian citizens in 1949, along with the rest of the Australian population, all of whom had previously been British subjects. Aboriginal people had the right to vote prior to 1949, however with citizenship granted in that year their right was confirmed.

The second event occurred on 3 June 1992, when the Australian High Court delivered the Mabo decision. The Mabo decision famously rejected the doctrine of terra nullius, therefore recognising that Aboriginal and Torres Strait Islander peoples have always had a special relationship with the land. This essentially progressed into land rights known today as native title.

The annual celebration of National Reconciliation Week frames these major events and provides a time for all Australian people to reflect on the past, present and future. It celebrates and builds on the positive relationships shared by Aboriginal and Torres Strait Islander people and other Australians, encouraging all Australians to explore ways that they can contribute to the national reconciliation effort.

This year's theme Let's Talk Recognition examines the next steps to properly recognise Aboriginal and Torres Strait Islander people not only for their cultural longevity and resilience, but also for their ongoing and consistent contribution to Australia's national identity. Events such as National Reconciliation Week allow the journey towards reconciliation to continue and strengthen.

The National Reconciliation Week website lists a variety of events that you can attend. What will you do this week to show your support for reconciliation?

Links:

MV Blog: From Little Things

National Sorry Day

Author
by Katrina
Publish date
27 May 2012
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Your Question: What does National Sorry Day commemorate?

From the late 1800s up to the early 1970s, the Australian government implemented the systematic removal of Aboriginal and Torres Strait Islander children from their families through a range of assimilation and 'protection policies'. In Victoria, for example, the Aborigines Protection Act 1869 had the broad powers to make laws for 'the care, custody and education of the children of Aborigines'. However these policies were solely based on the premise of race, with the aim to absorb or assimilate Aboriginal and Torres Strait Islander children of mixed descent into the non-Aboriginal community. Not only did these policies have lasting affects on families and community, but they were also active in suppressing Aboriginal languages and culture. Today, the people affected by the government removal policies are remembered as the Stolen Generations.

Australian Human Rights Commissions Bringing them Home Report 1997 Australian Human Rights Commission's Bringing them Home report, 1997.
Image: Cover Photo: Heide Smith, ‘Story Time’
Source: Australian Human Rights Commission
 

In 1997 the Howard Government released the Bringing them Home report as a recognition and tribute to the many families affected by forced removal. The main finding of the report was that 'between one in three and one in ten Aboriginal children were forcibly removed from their families and communities in the period from approximately 1910 to 1970'. The report recommended that the first step in healing is the acknowledgement of truth and the delivery of an official apology, which was provided by Kevin Rudd in 2008.

Another recommendation was that a National Sorry Day should be declared. National Sorry Day was first held on 26 May, 1998; exactly one year after the Bringing them Home report had been published. It encourages Australian society to acknowledge the impact of the forced removal of Aboriginal and Torres Strait Islander children, which is still felt by families and communities today. This annual event is marked with marches, speeches and presentations being held throughout the country, all of which aim to highlight the rights of Aboriginal and Torres Strait Islander Australians and a commitment to reconciliation.

Got a question? Ask us!

Links

National Sorry Day Committee

Reconciliation Australia

Share Our Pride

Australian Human Rights Commission

Mesopotamian lunar table

Author
by Martin Bush
Publish date
25 May 2012
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Martin is the programmer at the Planetarium at Scienceworks.

A personal highlight for me in The Wonders of Ancient Mesopotamia exhibition is the Babylonian lunar table. I love this artefact not just because of the antiquity of its writing or how long it lay preserved in the ground, and certainly not just because of the skill needed to make the rows of tiny cuneiform script. (How did they do it? I could never have managed.)

Babylonian lunar table Lunar table K.90 from the British Museum on display in The Wonders of Ancient Mesopotamia.
Source: © The Trustees of the British Museum
 

This tablet is exciting because shows just how seriously Mesopotamian cultures took astronomy. Observers recorded the appearance of the Moon – and also the stars and planets – every single night of the year. (Ok, unless it was cloudy.) They sent reports of these observations to the king. Babylonian astronomers had centuries of astronomical observations to work with. Unfortunately we don’t as not so many of these reports have survived.

Some concerns of these ancient astronomers – like making horoscopes to advise the king – are no longer of much interest to modern astronomers. But many ancient achievements live on to this day. Astronomers still number lunar eclipse using a system known as the Saros Cycle. This cycle was discovered by Babylonian astronomers around the 5th century BCE.

The work of these Babylonian astronomers can also be seen in the Jewish calendar. Sometime around the 4th Century BCE Mesopotamian astronomers calculated the average length of the lunar month. The extensive observations they had to work with meant that they came up with a remarkably accurate figure, different to the modern value by only a fraction of a second. This value was taken up by Greek astronomers such as Ptolemy and from there it was incorporated into the Jewish calendar when it was codified in the first millennium CE. The value determined by Babylonian astronomers is still used today to determine the date of the Jewish New Year.

This lunar table survived for centuries in the ground while the influence of Mesopotamian astronomy on our study of the skies has lasted even longer.

Orange army on the sea floor

Author
by Kate C
Publish date
23 May 2012
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Every year, thousands of Giant Spider Crabs (Leptomithrax gaimardii) congregate in Port Phillip Bay ahead of their annual winter moult.

When solitary, these crabs are often hard to spot; algae, sponges and sea squirts set up shop on their shells and provide excellent camouflage. However when the crabs aggregate and march, this hungry army is easy to spot. They scavenge whatever food they can find, including the wildlife on the shells of one another. The spectacle of hundreds of large orange crabs against the bare, sandy sea floor is an amazing sight.


It’s still a bit of a mystery what the aggregations are all about but senior curator Dr Julian Finn has some ideas from several years of observation.

Like many crustaceans, Giant Spider Crabs are protected by their hard body shell, rather like a suit of armour. The trouble is that a hard shell doesn’t allow room for growth. Crabs must shed their old skin to get bigger; they can expand their size in the brief window before the new skin hardens. The process of moulting takes up to an hour and all the crabs in an aggregation moult almost simultaneously.

Spider crab emerging Spider crab emerging from its old shell. The new shell is a vivid orange colour.
Image: Julian Finn
Source: Museum Victoria
 

Newly-moulted Giant Spider Crab Newly-moulted Giant Spider Crab in its fresh orange shell.
Image: Julian Finn
Source: Museum Victoria
 

A soft, freshly-moulted crab is irresistible to predators such as rays, seals and birds. By aggregating in the thousands an individual crab reduces its chance of being eaten, much the same way as mammals in herds find protection in numbers. Movement into shallow waters may help the crabs, usually dispersed throughout Port Phillip Bay, aggregate in a single mass and gain refuge from the strong tidal currents that scour the deep channels.

An earlier explanation that the annual aggregations were related to mating has thus far proved unlikely, as following the moulting of tens of thousands of crabs, only the odd couple has been observed to mate. We still don’t know however what happens when they disperse back into deep water. Julian believes this sudden influx of tender crab meat is an important part of the Port Phillip Bay food chain.

Spider crab moults Hundreds of cast-off spider crab moults on the sandy seabed.
Image: Julian Finn
Source: Museum Victoria
 

If you'd like to see some Giant Spider Crabs without the need for SCUBA gear, have a look at the entrance of the Marine Life exhibition at Melbourne Museum.

Next Wave and CSIRAC

Author
by Kate C
Publish date
21 May 2012
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Zoe Meagher's performance and audio tour, Goodbye, CSIRAC, takes place at Melbourne Museum this week as part of the 2012 Next Wave Festival. Described as "a love letter to 1960s computing and sci-fi", Goodbye, CSIRAC reflects upon a long-gone era when computers occupied whole rooms and ran programs that women punched into paper tape.

Goodbye, CSIRAC performance A performance of Goodbye, CSIRAC at Melbourne Museum.
Source: Museum Victoria
 

Zoe's fondness for first-generation computers was forged while working at Melbourne Museum, where CSIRAC now lurks in the lower ground floor. Zoe was also inspired by former technical assistant Kay Thorne, who recalled that that prior to CSIRAC, the same kinds of calculations were done by female workers who were also called computers. In Goodbye, CSIRAC, Zoe performs as the Ghost of Computers Past, an amalgamation of these long-gone human and mechanical computers. "The idea that these human, female computers were replaced by CSIRAC, which was in turn replaced, led to the Ghost," says Zoe.

Zoe pondered what CSIRAC would say if it had a voice, and what it would want us to remember. With slow, robotic movements and draped in eerie gossamer, her Ghost appears in several locations as the audience is directed through exhibits by the audio guide. Plugged in to the Ghost's  thoughts and feelings, this closed soundscape unifies the small audience group while simultaneously isolating them from other museum visitors. In a surprisingly touching moment the Ghost asks to meet the computers in the pockets of the group. "Is she your first?" she asks, as she mourns the discarded models that came before them: "Did you wipe her memory first?"

Interspersed with the melancholy monologue of the Ghost are extracts from articles in the 1960s that promoted computer programming as an excellent career choice for girls. A quote from a prominent computer scientist of the day claims that since the discipline shares the fundamental requirements of dinner-party planning, such as planning and patience, women have a natural aptitude for it. Zoe explains that it was considered an "appropriate feminine occupation, much like clerical work, and largely unacknowledged." What happened to these women, and how did computer science became the male-dominated field it is today? In an absorbing and immersive way, Zoe's Ghost invites the audience to consider the changing fate of female computer operators and their machines.

Goodbye, CSIRAC is a free performance that runs from 22-27 May at Melbourne Museum. Each show is limited to 12 people so bookings are essential. Book online through the Next Wave website or call 1300 30 40 72. Bookings do not include general entry to the museum.

Links:

Next Wave 2012: Goodbye, CSIRAC

CSIRAC in Collections Online

CSIRAC website

About this blog

Updates on what's happening at Melbourne Museum, the Immigration Museum, Scienceworks, the Royal Exhibition Building, and beyond.

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