MV Blog

On 18 February 1930, Clyde Tombaugh achieved an amazing feat - he discovered Pluto. It’s said that he was a meticulous astronomer and I’m sure he must have needed all that mettle to have stumbled upon the tiny speck that was Pluto.

Over six years ago, Pluto grabbed headlines when astronomers famously ‘demoted’ the planet and designated it as the first of the dwarf planets. Some were disappointed by this – but I have to say that Pluto has always been a bit of an odd-ball. It was something we had explored a year earlier with the release of our planetarium show, The Problem with Pluto, in 2005.

In this planetarium show, Lucy is on a research craft with her mother Lillian, a scientist, and together they are gathering data to discover just what Pluto’s status should be.
Image: Melbourne Planetarium
Source: Museum Victoria  

A fellow astronomer shared with me his interesting way to explain it. Imagine, as a child, having a case full of pencils. The pencils came in all different colours but at their heart they were the same; except for one. It was a bit odd, still good for colouring-in just like a pencil, but there was something different about it. Nonetheless, it was the only one you’d even seen and it had always been in the pencil case, so you called it a pencil along with all the others. Then, one day at a friend’s house, you opened their pencil case and it was filled with something called crayons. Your eyes lit up with recognition. That odd-ball pencil you’d been worried about wasn’t odd after all, it was in fact a crayon.

When Pluto was discovered, it was one of a kind at the edge of the Solar System. It wasn’t a terrestrial planet, it wasn’t a gas giant, but it did orbit the Sun. Seventy years on, we now know of thousands of objects orbiting alongside Pluto. They are the icy worlds that make up the Kuiper Belt. Pluto, because it is big enough to be round, is still a bit special and so it now goes by the new label of dwarf planet.

On Pluto Day, I’ll be celebrating that Pluto has now found its rightful place in the Solar System.

Right now, a real research craft is on its way to Pluto. Called New Horizons it will fly by Pluto in July 2015 and journey on to discover more about the Kuiper Belt.
Source: NASA                        

Links

The Problem with Pluto will be showing at the Melbourne Planetarium at 2pm, 18 February to 4 March.

Like other Australian astronomers last night, I was glued to the computer watching as a fire raged across the Warrumbungle National Park in NSW, home to Australia's world-class optical and infrared telescopes at Sliding Spring Observatory. I think the hardest thing was knowing that it's almost 10 years ago to the day, that fires destroyed the Mt Stromlo Observatory in Canberra. Could this really be happening again?

A truly frightening image, as Australia's largest optical telescope, the Australian Astronomical Telescope (AAT), is engulfed in smoke.
Source: Rural Fire Services  

Fires blaze around cottages in front of the AAT. To the top right of the image are the flames that engulfed the lodge.
Source: FTS webcam  

The glow as the astronomer's lodge is destroyed. Temperatures at the AAT were measured to be over 100 degrees.
Source: FTS webcam  

Thankfully, lessons were learnt from that event and there is much hope that measures put into place may have saved the dozen or so telescopes on the mountain. We'll have to wait and see as the damage is assessed over the next few days.

The good news is that all 18 staff were evacuated safely. Many telescope domes are still standing, as new images come through this morning. The building which has been destroyed was the lodge which provided accommodation for astronomers during their observing runs. 

Electronics were not meant to survive such temperatures.
Source: HATSouth webcam  

The picture I wanted to see today. The AAT dome still stands, but there will be a wait to access how the telescope fared inside.
Source: LCOGT webcam  

Our thoughts are with the community of Coonabarabran and those who have been affected by the fires, and our thanks go out to fire services for their great efforts. 

If the telescopes had been destroyed it would have been devastating for Australian astronomical research, all but ending our ability to do continue doing optical astronomy here. Hundreds of researchers and students rely on those telescopes. And it would also have affected the Coonabarabran community, many of whom rely on the telescopes for their livelihoods too.

Images of the event, many taken from the webcams that are normally used by astronomers to check sky conditions during their nightly observations, tell the story.

The burnt out remains of the astronomers lodge. I have fond memories of Margaret's delicious chocolate pudding, which I would devour there, before heading up to the telescope for the night's observing run!
Source: Rural Fire Services

The square "dome" on the left houses the ANU's 2.3 metre telescope which stayed a comfortable 20 degrees throughout the fire. The dome to the top right is the new SkyMapper telescope, led by Nobel Laureate Brian Schmidt and built to continue the work of the Great Melbourne Telescope after it was destroyed in the Mt Stromlo fires. Temperatures there peaked at 65 °C.
Source: Rural Fire Services  

UPDATE: 

The Warrumbungle Shire Council has set up a Warrumbungle Shire Mayor’s Bushfire Appeal with donations being used solely to assist residents affected by the fire. The NSW Rural Fire Service are reporting that some 40 properties and over 110 out-buildings have been confirmed lost as well as a large number of livestock and farm machinery.

Links:

Siding Spring after the fires of January 2013 via Observations Blog, Sydney Observatory

Report from The Australian

Astropixie liveblogging the fire: Sunday night and Monday morning

Matilda swapped a life working as an engineer for a life curating the museum’s historical Engineering collection. She’s very curious about how stuff works, how it’s made and why. If a machine’s got a switch, she’ll definitely flick it.

Last week I visited a foundry in Melbourne that was casting a vital component for our restoration of the Great Melbourne Telescope. The original part of the telescope - the declination disc - had been modified and broken at some time in its history and was not repairable.

The Great Melbourne Telescope in its own house at the Melbourne Observatory, 1870. The red arrow points to the declination disc needing replacement.
Source: Museum Victoria  

This is the first part of the project to be made by a sand moulding or casting process very similar to that which was used in Ireland in the late 1860s. Our modern part is made from a type of cast iron invented in the 1940s which has magnesium added to give it properties that make it easier to shape. The electric induction furnace, which is used to melt the metal, was developed in the early 20th century.

A couple of weeks ago, Peter made a pattern out of wood for the casting. Tom next used the pattern to form a hollow in a sand mould. This kind of mould is a mixture of washed sand and a binder, made in two halves, and cured to retain its shape once the pattern is removed. The two halves of the mould were then closed, after a pouring spout, flow paths and risers (to allow the metal to flow to and fill all sections of the hollow) were added. Heavy weights on top ensured it remained closed when the metal was poured.

The sparks fly as Bryn takes a sample from the furnace for temperature testing.
Image: Matilda Vaughan
Source: Museum Victoria  

The pounded earth floor and the filtered light through the open doorways and skylights in the roof of the foundry transported me back in time. It was 7 AM and Bryn had already been awake for hours and the sparking pot of molten metal (spheroidal graphite iron) was his morning's labour. He tested its temperature and composition, turned the knob of the electric induction furnace's control panel, and gave the signal. After the removal of the slag crust, the metal was ready for pouring.

Bryn pours the molten metal into the next mould as Tom looks on. Our filled mould is on the floor behind them.
Image: Matilda Vaughan
Source: Museum Victoria  

Bryn added the final ingredients and carefully tipped the 1500°C molten metal into the pre-heated ladle. He then transported the ladle to the moulding area and poured it first into our waiting mould, and then onto the other smaller moulds. Being such a large casting, ours needed almost 24 hours to cool down before breaking open the mould.

The lower half of the sand mould, with the casting removed. The sand from the top half is in pieces in the background. The sand will be cleaned and reused, as will the molten scraps of metal.
Image: Matilda Vaughan
Source: Museum Victoria  

At 6 AM the following morning, Bryn was ready to break open the mould. The weights were removed and the upper part of the mould lifted away. Then the casting itself was lifted into the air and the sand and metal debris removed. It was then transported by the overhead mobile crane to the finishing room, where the hardened parts of the spout, risers and flow paths were ground and knocked off and the surfaces cleaned.

Bryn (left) with the pattern for our declination disc, and Tom (right) with the freshly removed casting. Note the four cylindrical 'risers' at the edge, the pouring pathways (almost like a running person) in the middle and the square shaped pouring spout (head of the running person). These pieces are reused for the next batch of metal.
Image: Matilda Vaughan
Source: Museum Victoria  

The next step for this part will be heat treatment to 'relax' the metal, followed by the final shaping and machining. It is a rare sight to see this process so close in our urban environment and one of the great aspects to working on restoration projects of this magnitude.

Links:

Great Melbourne Telescope website

Great Melbourne Telescope on Collections Online

I had never seen a total solar eclipse before, and I was very excited to travel to Queensland to watch Australia's first solar eclipse in a decade just before 6AM this morning. 

It was incredible to wander down to the beach at 4AM and see it already packed with eclipse chasers! Thousands of people were at Palm Cove alone, more in surrounding Cairns and Port Douglas, while some headed inland where the weather prospects were better.

Eclipse chasers on the beach at Palm Cove, Queensland, awaiting the total solar eclipse.
Image: Tanya Hill
Source: Tanya Hill  

We saw a magnificent sunrise over the water, but minutes later, when the partial eclipse was due to begin, the Sun disappeared behind clouds. It was an anxious wait but half an hour later, the clouds parted and we all donned our eclipse glasses to see a large chunk missing from the Sun.

The totality was perfect. Just beforehand you could tell that the surrounding light was different; it seemed sharp and unnatural. Then the brilliant diamond ring effect lit up the bottom of the sun and the moment had begun.

The moment of perfect totality, when the Moon was exactly in front of the Sun.
Image: Tanya Hill
Source: Tanya Hill  

I was amazed by the colour - we could really see the pink prominences dancing around the Sun. Everyone cheered and just enjoyed the beauty of this natural show. We could see Venus shining bright above the Sun, the wispy corona and the Sun's outer gaseous layer, along with a dazzling bright ring encircling the Moon. It was surprising how long the two minutes lasted. The second diamond ring effect was blinding and spectacular as the Sun began to emerge once again.

The Yolngu of Arnhem Land tell their eclipse story of the sun-woman and moon-man coming together in the sky as husband and wife. It struck me that this is a phenomena that has been seen by so many, across thousands of years. I feel so fortunate to have shared in the experience.

Links:

'Eclipse groupies take shot in the dark,' The Age, 11 November 2012

'Eclipse sheds light on sizzling sun,' The Age, 14 November 2012 

Coming up on the 14th November we have the chance to see a solar eclipse. From here in Melbourne it will be a partial eclipse, with 52 per cent of the Sun's diameter covered by the Moon. But up in Far North Queensland and the topmost of the Northern Territory, they will be treated to totality, where the Moon will completely block the Sun for just on two minutes.

A partial eclipse will be seen from Melbourne on the 14 November 2012.
Source: Museum Victoria  

The eclipse will occur during the early morning of 14 November, with the Sun still low in the east. Therefore, a good view of the horizon will be needed. The timing for Melbourne is as follows:

It is important never to look directly at the Sun, even during an eclipse. While the Sun may appear less bright it can still cause long lasting eye damage.

There are safe ways to look at the eclipse – at the Scienceworks shop you can purchase eclipse glasses that will allow you to watch the event, while protecting your eyesight.

You can also create a simple "pinhole" projection. It's as easy as making a small pinhole in a piece of paper or cardboard. Do not look through the hole, but allow the Sun to shine through and project an image onto a second piece of cardboard. Even a blank wall or clear patch of ground can make good surfaces for projection.

Sometimes nature helps out too. If you can see sunlight travelling through the leaves of a tree, you’ve got yourself some ready made pinhole projections. Check the ground and it might be covered with little crescent Sun images. Take a look at this great example on the Astronomy magazine website.

I’ve never seen a Total Solar Eclipse, so I'm heading up to Queensland for my first chance. I've been told that it's quite an eerie experience to have darkness fall while it's still early morning.

If you will also be in the path of totality for this eclipse, then be sure to check out the Eclipse Megamovie Project. Use your smartphone to upload images and videos of the Sun during totality and the Space Sciences Laboratory in California will combine the footage to create the first ultra-high time resolution movie of a solar eclipse.

What I'm most looking forward to is the chance to see the Sun's corona, the bright and tenuous gas that surrounds the Sun. Normally it's invisible, drowned out by the Sun's glare, but being able to see hidden things is something that's always captivated me about astronomy.

During totality the Sun's diffuse corona and thin pink chromosphere can be seen.
Source: Luc Viatour. www.lucnix.be  

Your Question: How can my wife and I gaze at the full moon together, but from opposite sides of the globe?

Our enquirer is in Jervis Bay, on the East Coast of Australia. His wife is in Ottawa, Canada. They contacted Museum Victoria to ask if we can help them plan a romantic evening – a full Moon-gazing date on opposite sides of the Earth.

A full moon seen from Ontario, Canada.
Image: Michael Gil
Source: Wikimedia Commons  

The next full Moon will occur on the 1^st or 2^nd of August 2012 (depending on what time zone you are in). In Ottawa, the Moon will rise at 7:55pm EDT (Eastern Daylight Time) on 1 August. It will be at its absolute fullest at 11:27pm and will continue to be visible until it sets on 2 August at 6:28am.

Sadly in Jervis Bay's time zone, the full Moon will occur when the Moon is not visible from that side of the Earth, at 1:27pm AEST (Australian Eastern Standard Time). The Moon will have set that morning at 6:24 and will not rise again until 5:32 that evening.

All is not lost, however. The Moon-watching date can still occur, just not at the precise moment when the Moon is at its fullest. Our couple will just have to wait a few hours.

When the Moon rises on the night of 2 August in Jervis Bay (at 5:32pm AEST), it will be 3:32am in Ottawa (EDT). The Moon will be visible in both places and will remain so until it sets in Ottawa at 6:28am (EDT). This means our two Moon-gazers can watch the still-very-full Moon "together" for nearly 3 hours.

If the idea of getting up so early diminishes the romance from the Canadian perspective, our Moon-gazers can wait a few days – if they are happy to look at a Moon that is no longer full.

On 4 August, the Moon will rise in Jervis Bay at 7:38pm (AEST). It will be 6:02am in Ottawa (EDT). The Moon will be visible in both locations until it sets in Ottawa at 8:48am. Unfortunately this means the Canadian half of our Moon-gazing couple will be looking at the Moon during daylight (the Sun will rise in Ottawa on 4 August at 5:51am).

While arranging this date was tricky, it was only possible because our lovers are not on exactly opposite sides of the Earth. If they were, there would be no chance of viewing the Moon that the same time (for more than an instant and only then if they had a perfect view of the horizon). And one of them would have to be in a boat. Less than 4% of all land on Earth (and no part of the Australian mainland) is antipodal (diametrically opposite) to land: the antipode of Jervis Bay is in the North Atlantic Ocean; the antipode of Ottawa is in the Indian Ocean.

Maps showing Jervis Bay, Australia, and its antipode, in the North Atlantic Ocean.
Image: Antipodes Map
Source: Antipodes Map  

Links

Melbourne Planetarium: Skynotes

Melbourne Planetarium: Moon Phases

US Navy: Rise/Set times for Sun/Moon

Antipodes Map

timeanddate.com