Return from Ridge A

We have recently returned from 6 days / 5 nights camping on the high Antarctic plateau at a place known as Ridge A: the driest and possibly coldest place on Earth. Our mission was to refuel and refurbish an existing robotic observatory (the Plateau Observatory; PLATO), which supplies power and communications to a 0.6 m terahertz telescope (the High Elevation Antarctic Terahertz telescope; HEAT).

After around a week of weather delays at the South Pole, our Twin Otter pilots were finally given the go-ahead to fly us to this remote location. Although 25 knot winds were forecast, the previous week’s experience had shown us that the winds were typically overestimated, and hence this was not considered to pose any threat.

Around 4 hours after departing the South Pole, we landed at Ridge A. It turns out that the weather forecasts were spot on: -40 degrees C and 20-25 knot winds. If you believe in the “windchill factor”, this pushes temperatures down to near -60 degrees C. A preliminary review of data from an automated weather station at nearby Dome A suggests that this may possibly be the worst (windiest) weather in recorded history! Just our luck.

After ripping apart some failed electronic components from the modules (which were sent back via the same Twin Otter to the South Pole for repair), we quickly went into “survival mode”, huddling around in a tent with hot drinks provided to us by our mountaineer/guide.

For the remainder of our time at Ridge A, the winds died down but were still stronger than usual, making work a lot harder than anticipated. Thankfully, we had two large “work tents” designed to shield us from the wind and perhaps even provide a (relatively) warm work environment. The temperatures at Ridge A varied from approximately -45 C at local midnight, to -35 C at local midday (keep in mind the Sun never sets). A few hours after local midday, our tent was usually around freezing (0 degrees C), which meant we could comfortably work in just thin glove liners.

We were only meant to spend a couple of nights in the field, but once again weather delays meant we were trapped at Ridge A for much longer than anticipated. Although the extra time was utilised (and in fact proved to be a blessing given the harsh working conditions), nothing can describe the relief we felt on the 6th day when we received word that a Twin Otter was on its way to take us home. The same aircraft would deploy the remainder of our team in the field in a “tag team” like fashion..

I am writing this blog entry from the South Pole, where -25 degrees C has never felt so warm. The past 6 weeks in Antarctica has been an incredible experience. We have slept in an igloo at the foot of an active volcano; watched seals and penguins dance on the ice; spent a couple of weeks at the geographic South Pole; and of course camped at the driest, coldest, and one of the most remote and inhospitable places on Earth: Ridge A. The last of our team are due to return from the Ridge A campsite later tonight. We will all begin the journey back to Sydney tomorrow.

Detailed daily accounts of our adventures as well as view many more photographs and time lapse videos, are available for viewing at our blog.

Geoff

(Geoff is one the wonderful casual staff that work at the Observatory while he is completing his Ph.D)

The Sun with large sunspots on the morning of 16 January 2013. Photo Nick Lomb

Sunspot group AR1654 is a large one with strong magnetic fields and is a likely candidate for the emission of a strong flare. Will these possible flares and that from other sunspot groups during 2013 and 2014 affect the Earth’s atmosphere and do other damage on Earth? I spoke about this to Nicole Dyer on ABC Local Radio Queensland on Monday 7 January 2013. The recording for which I was honoured with the new title of ‘astronomist’ is here. Note that the new name for the profession is not a bad one and may just catch on since an ‘anatomist’ examines human and other animal bodies why shouldn’t someone who observes celestial bodies be called an ‘astronomist’?

What is a flare? A flare is an explosion on the Sun that is usually associated with regions of strong magnetic activity, that is, generally sunspot groups. Flares can result is the emission of strong radiation and sometimes also of charged particles. These days flare intensity is measured by satellites with their intensity classified on a scale that increases by a factor of 10 between classes: A, B, C, M and X. Each of these is subdivided into classes with the most intense flare recorded in recent times being one of X28 and possibly even higher on 28 October 2003.

The most intense flare seen on the Sun was on 1 September 1859. White light drawing by Richard Carrington in Monthly Notices of the Royal Astronomical Society Volume 20 page 13 1859

On 1 September 1859 British astronomer Richard Carrington was drawing sunspots (just like Harry Roberts, who makes frequent contributions to this blog, does today). He projected the image from his telescope onto a white screen forming a 27.5-cm wide image of the Sun’s disc. At 11:18 GMT he was just finalising his drawing of the various sunspots when ‘two patches of intensely bright and white light broke out, in the positions indicated in the appended diagram (above) by the letters A and B, and of the forms of the spaces left white’. Within a minute Carrington ‘was mortified to find that it was much changed and enfeebled’. The whole visible event lasted for five minutes with Carrington noting the last traces at C and D on the diagram with the light of the flare vanishing as ‘two rapidly fading dots of white light’.

In his summary of the event Carrington notes that 16 or 17 hours after the event there was a huge magnetic storm. He states, however, ‘While the contemporary occurrence may deserve noting, he would not have it supposed that he even leans towards hastily connecting them’.

Of course, the two events were connected. As often happens, the flare was followed by a Coronal Mass Ejection which sent a large cloud of charged particles towards the Earth. A CME usually takes between one and five days to reach the Earth, but in this case the speed of the ejection was exceptionally high and the particles arrived in under a day.

It is the CMEs that can have a considerable effect on the Earth and its magnetic field. In 1859 in what we now refer to as the ‘Carrington event’ telegraph communications were disrupted with some operators receiving electric shocks and some of the paper recording the dots and dashes set on fire. In March 1859 during a magnetic storm due to a CME strong surges took place in electricity transmission lines in Canada leading to an electricity blackout lasting eight hours. More recently, in December 2006 signals from GPS satellites were affected by a CME.

It is clear that flares and associated CMEs can disrupt communications on Earth. The strongest flares and CMEs tend to happen during the peak of the 11-year cycle of solar activity. We are near the maximum of the solar cycle, so flares and CMEs can be expected. However, the current solar cycle, cycle no 24, seems to be the least active for almost a century and hence the likelihood of another intense event such as that witnessed by Richard Carrington in 1859 or like the one in 1989 that caused chaos in Canada is not high. During the peak of the next cycle in 11 years’ time or the one after we may need to start to worry about disruptions to our super smartphones!

Yesterday (2nd January, 2013), two weeks after departing Sydney, we arrived at the South Pole. I am here as part of the USAP (United States Antarctic Program), on a joint Australia/American expedition. Our goal is to service a remote (unmanned) robotic observatory at a site called Ridge A.

Ridge A, approximately 1000 km from the South Pole, is thought to be the driest place on Earth. Here, at a physical altitude of approximately 4050 m, the water vapour content of the atmopshere is so low that far-infrared wavelength (or THz frequency) radiation, that is typically absorbed at almost any other location (even the Atacama desert in Chile), is able to reach the ground. Certain spectral lines in this region will provide important clues concerning the evolution of molecular clouds: the places where stars are born.

Prior to arriving at the South Pole, we spent a few days in Christchurch, New Zealand (the base of USAP operations), and then around a week or so at McMurdo, which is the largest US station, home to approximately 1000 people during summer. At McMurdo we organised all our equipment and camping gear, as well as undertook crucial survival training which included a “night” camping in ice trenches (and igloos!) in front of a smoldering active volcano. I say “night” because during summer in Antarctica, the Sun never sets.

Now that we have made it to the South Pole (or simply “Pole”, as it is affectionately known as around here), we will be acclimatising to the altitude and preparing to be deployed to possibly the more remote place on the planet, where we will camp for 5-7 days in temperatures down to -50 degrees C. If all goes well, the observatory and telescope will then run for a further 12 months, at which time another team will be deployed for the annual service.

There is an interesting article written about the expedition, in which our chief scientist, Dr Craig Kulesa of the University of Arizona, is interviewed. It can be viewed here:

http://antarcticsun.usap.gov/science/contenthandler.cfm?id=2780

I will try and report in later, but internet access here is sporadic at best (they use decommissioned geostationary satellites, whose orbits have decayed sufficiently to allow them to be seen from the polar regions). For now, you may details of our adventures which are documented in an almost daily blog at:

http://www.phys.unsw.edu.au/~z3318051/spd/

Geoff Sims

Close-packed spheres (oranges) in a regular sequence. Picture Nick Lomb

Jupiter is the largest planet in the solar system and much larger than the Earth. One way of illustrating the size difference is to ask how many earths could fit inside Jupiter. Taking the question to mean how many times the volume of Jupiter is larger than that of Earth, the answer can be can be easily found to be 1300 by taking the ratio of the cubes of the diameters of the two planets. What though if we take the question more literally to mean that how many earths could be stacked inside Jupiter? What then is the answer?

Here we run into the well-known stacking problem, which is the consideration of the most efficient way of stacking spheres into a container. Amazingly, this problem was first considered by none other than the German mathematician, who is famous in the history of astronomy, Johannes Kepler.

The portrait of a man, believed to be Johannes Kepler, painted around 1611 by Hans von Aachen, courtesy Wikimedia Commons

In 1611 while living in Prague as Imperial Mathematician to Emperor Rudolf II Kepler wrote an essay called, in Latin, “Strena seu de Nive sexangula” or, in English, “New-Year’s gift concerning six-cornered snow”. In this essay instead of looking at the movements of planets, Kepler looks at the structure of snowflakes and in particular their sixfold symmetry. Though, of course, without modern knowledge of crystal structures he could not explain this symmetry he did explore some interesting mathematical concepts along the way.

Inspired by seeds in a pomegranate Kepler considered the most efficient way of packing spheres into a container. He conjectured that the best way was the simplest – putting each sphere into the hollow formed in between four spheres below, a method that is used by every greengrocer to stack oranges and similar fruit.

Surprisingly, Kepler’s conjecture was only proved 1998 by American mathematician Thomas Hales in a 250-page proof accompanied by 3 gigabytes of computer programs. The proof was so complex that a panel of 12 referees took four years to report back that they are 99% certain of its correctness.

Taking Kepler’s conjecture as proved, how many earths can we stack, in this most efficient way, into Jupiter? A quantity called density is defined as the fraction of the available space occupied by the spheres. The higher the density, the more closely packed is the stacking. For this most efficient stacking method the density is ?/?18 = 0.7405. A derivation of this formula is below.

We can now state that the number of earths that we could fit into Jupiter is the number of times Jupiter’s volume is larger than that of the Earth multiplied by the packing density, that is, 1300*0.7405 = 963. Thus the literal and exact answer to the question “How many earths can fit into Jupiter?” is 963.

Derivation of the formula for density

Stacking circles in the most efficient way. Drawing courtesy Wikipedia

Let us first consider the 2-dimensional version of the stacking problem and let us take an array of n by n circles of unit diameter. Their total area will be n*n*?/4.

Looking at the above image the length of n circles is n.

To work out the height of n circles note that the centres of two circles in one row form an equilateral triangle with the centre of a circle above and in between them. Thus the vertical distance between the centres is sin 60° = ?3/2 and the height of n circles is n*?3/2.

The total available area is length times height or n*n*?3/2.

Density for this 2-dimensional case is thus area of circles/available area = ?/4 divided by ?3/2 after the n*n factor cancels out. Density = ?/?12 = 0.907

For three dimensions the derivation is similar. We take an array of n by n by n spheres of unit diameter. Their volume is n*n*n*4/3*?/8 = n*n*n* ?/6.

The length and width of the spheres are both n.

To work out the height of n spheres note that the centres of four spheres in one row form a pyramid of unit length edges with the centre of a sphere above and in between them. Simple trigonometry gives the height of the pyramid as 1/?2.

The total available volume is length times width times height or n*n*n*1/?2.

Density for this 3-dimensional case is volume of spheres/available volume = ?/6 divided by 1/?2 after the n*n*n factor cancels out. Density = ?/?18 as used in the calculation above.

Sir Patrick Moore photographed on 13 August 2008. Courtesy Rusty Sheriff and Flickr

Astronomers around the world have been saddened by the death of astronomy broadcaster, populizer and prolific author Sir Patrick Moore. As reported in the media, Sir Patrick died at the age of 89 at his home in Selsey, West Sussex. He has inspired many of the current generation of astronomers, both professional and amateur, to take up the science. In Britain he was also widely known to the general public as well through his media appearances, especially through his record-breaking BBC television program, The Sky at Night.

Fellow curator at the Powerhouse Museum, Paul Donnelly, who trained as an archaeologist and grew up in the UK says, ‘during the whole of the 60 and 70s Moore was a VERY regular fixture on the Teev and his distinctive asymmetry and style was frequently (lovingly) parodied by comedians of the day!’

Sir Patrick was president of the British Astronomical Association in the early 1980s, after having joined the association at the age of 11. The current president, Professor Bill Leatherbarrow, says:

There can be few BAA members who do not owe their interest in astronomy to the influence of Patrick, either through his numerous publications or his monthly “Sky at Night” television programme. His enthusiasm was deeply infectious, and what he had to say was truly inspirational.

Patrick Moore was a prolific author. Here is a selection his books. Photo Nick Lomb

Patrick Moore came to my notice when I received the Boys’ Book of Astronomy as a prize in primary school. I met him many years later in 1982 when to my surprise I found that I was coordinating a visit by him to Sydney. As at that time he had just been awarded an honorary Doctor of Science, when I first met him I approached him with trepidation saying, ‘Dr Moore?’ He immediately put me at ease and asked me to call him Patrick like everyone else. Although he was unimpressed by my choice of hotel for him at the Rocks, the visit went well. On the evening of his arrival, there was an informal meeting with him over drinks for selected members of the NSW Branch of the British Astronomical Association (now the Sydney City Skywatchers) of which he was, and remained, patron. He was most pleasant and entertained the group that evening for hours with non-stop fascinating stories about astronomy.

During his visit Patrick also gave a talk on his special subject the Moon to a packed audience of Branch members at Sydney Observatory. As there were so many people that they could not all fit in the lecture room, a video camera was used to show the talk in the Observatory foyer to an overflow audience. This arrangement allowed the talk to be recorded and the video of the event still exists, now converted to DVD. In recent times parts of the DVD have been shown at Skywatcher meetings and I am sure that it will be shown again in the near future. Those watching the video will hear a great talk presented by someone who talks faster than anyone else that I have ever heard.

My last contact with Patrick Moore was when I wrote to him in 2008 on behalf of Sydney Observatory and the Sydney City Skywatchers to congratulate him on his 85th birthday. I was pleased to receive a gracious note from him in reply that had clearly been typed on an old and old-fashioned typewriter.

Sir Patrick Moore was a unique person, with great abilities, an excellent communicator and a wonderful ambassador for astronomy. He will be missed by his many many fans around the globe.

Green Island from the Coral Sea. Photo Nick Lomb

A few days after the 14 November 2012 total eclipse I visited Green Island on the Great Barrier Reef. This is a coral cay, that is a place where sand has accumulated on the coral, and eventually plant life developed on the sand so that most of the island is covered by rainforest. It is a small island of 12 hectares in area so that it is only a few hundred meters across.

Travel to Green Island is on a 50-minute boat ride from the city of Cairns. Just before reaching the island a crewmember gave a briefing on the PA system and I was thrilled to hear that Green Island was named by Lieutenant James Cook after the astronomer on board his ship, HMB Endeavour. There was also a sign with the same information prominently displayed on the island. That Green Island was named after Charles Green seems to be well known and is mentioned in an article on the astronomer titled Man without a Face – Charles Green published online by the Captain Cook Society.

This is interesting information as there few places in Australia named after an astronomer. Only one other spot comes immediately to mind: Dawes Point in Sydney, the location of the south pylon of the Sydney Harbour Bridge, named after Lieutenant William Dawes, the astronomer with the First Fleet. However, to see if this information correct let us take look at the evidence for the naming of Green Island.

Cook’s journals and a number of other relevant publications are available online from the National Library of Australia. In the entry for 10 June 1770 Cook states that ‘a low green woody Island laying in the offing bore N 35° East- this Island lies NBE1/2E distant 3 or 4 Legs from Cape Grafton — and is known in the Chart by the name of Green Island’. The wording in John Hawkesworth’s official account of the voyage is similar, ‘a low, green, woody island, which lies in the offing, N. 35 E. This island, which lies N. by E. ½ E. distant three or four leagues from Cape Grafton, is called in the chart GREEN ISLAND’.

This wording is slightly odd as the name could equally have been given because of the green rainforest that covers the island. Elsewhere Cook has no modesty in stating that he named a geographical feature plus he often stated his reasons. For instance, in the entry for two days earlier there are these examples:

* Between this Cape and Iron Head the Shore forms a large Bay which I named Rockingham Bay
* this point I named Cape Sandwich [in] Honour ye Earl of that name
* a fine large Bay which I call’d Halifax Bay it is well shelterd and affords good anchorage

So did Cook name Green Island after the astronomer? One theory would be that he did, but did not want to state it publicly as Charles Green was not a sufficiently important person such as, say, Lord Sandwich, mentioned above. This seems unlikely though for Cook did name places after members of his crew such as Point Hicks in Victoria that he named after Lieutenant Zachary Hickes. The official Queensland Government website sits on the fence stating that:

Named on his charts by Lieutenant James Cook RN (1728-1779) navigator, HM Bark Endeavour, 10 June 1770. Named either because of its vegetation appearance, or possibly after Charles Green (1736-1771), astronomer aboard Endeavour. Refer J.C. Beaglehole. Voyage of the Endeavour 1768-1771. Cambridge (UK) 1968, p.342.

Hence it seems that the jury is out on the origin of the name of the island. Still Green Island is a wonderful place to visit and provides an opportunity to reflect on an astronomer who had an important, yet little known, role in Australian history.

Nick Lomb

The famous photograph of the Earth from the vicinity of the Moon taken by the astronauts of Apollo 8 on 22 December 1968. Courtesy NASA

Round the Moon by Jules Verne. Free ebook available in a variety of formats from Project Gutenberg

I have recently read this book by Jules Verne and was struck by the number of uncanny similarities between this imaginary voyage that Verne describes as happening in the 1860s and the first lunar circling mission of Apollo 8 made a century later. What is also fascinating is to see how impossibly difficult such a voyage would have been at that early date without the benefit of the electronics and radio communications that were available to the Apollo 8 astronauts. As well, part of the fun of reading this book is to see what parts of the science of a lunar mission Verne gets right and what he gets wrong.

Round the Moon is a sequel to From the Earth to the Moon. This first book tells the story of the construction of a giant cannon to shoot a shell to the Moon. It is a project of the Gun Club in Baltimore, USA, that was set up by former military artillery officers. With the advent of peace after the American Civil War of 1861-1865 these officers were getting bored and their president thought that they needed a major project to boost their spirits.

The 274-m long cannon was set up in Florida to shoot the projectile at the Moon. Initially, the 2.7-metre wide projectile was to be unmanned but a French adventurer arrives and insists on riding inside the capsule and persuades the president of the Gun Club and his chief critic to join him.

Round the Moon begins just after the projectile had been fired. The three occupants survive, of course, in the book. Should they have? According to my calculations to reach the target velocity of 11 km/s, the Earth’s escape velocity, in the 274-metres long gun barrel, they must have traversed it in 0.05 seconds and experienced an acceleration of 22 500g! For comparison, the highest accelerations that humans are known to have survived have been the 100-200g experienced by racing car drivers involved in crashes.

Leaving the miraculous survival of the three pseudo-astronauts aside, during the journey there is a lot of fun conversations and interesting speculations about the possibilities for an atmosphere and inhabitants on the Moon. The travellers miss the Moon as on the way they happen to have an encounter with an unknown satellite of the Earth that deflects the spacecraft into an orbit around the Moon. Fortuitously, but just a little implausibly, a later encounter with a giant asteroid deflects them on a path back towards the Earth. Very cleverly, Verne has them travelling at full Moon, so that when they are flying over the unseen side of the Moon it is unlit by the Sun and so the travellers can see nothing of the then unknown surface.

Some of the science in the book seems be correct, but there are quite a few errors. The travellers still experience the Earth’s gravitational pull as they fly away from the planet with just the normal diminution by the square of the distance. The only time they find themselves in zero gravity is when they reach the point where the gravitational forces of the Earth and the Moon are in balance (the L1 point) and afterwards they feel the Moon’s attraction. Of course, a spacecraft moving along an orbital trajectory is basically in free fall and so the environment should have zero g, or more correctly, microgravity.

The book is most enjoyable to read with lots of banter between the three travellers and interesting descriptions of what the surface of the Moon facing Earth would look like when viewed from close-up. For a modern reader though the best part is to find the parallels to the Apollo flights a century later, especially that of Apollo 8 that first looped around the Moon, and to consider the science given in the book to see what is right and wrong. I have mentioned a few problems that I have found in this review, but there are others. For instance, check out the discussion of what a lunar eclipse may look like from the Moon.

For me, possibly the most important aspect is how Round the Moon highlights that until the right technology comes along, such as rockets, electronics and wireless communication in this case, many projects are impracticable and can only be achieved in the imaginative mind of a clever writer of fiction.

The magnetic field on the Sun at the last solar minimum in 2008 and at the current solar maximum. Courtesy Lockheed Martin Solar and Astrophysics Laboratory

Kathleen asked:

Thanks for the page harry Reports !! I was wondering if this two year delay is relatively new? the article said last reversal was delayed 2 year. i was curious about the north hemisphere explosion and collapse of the sun Jan 2012 which a lot of net chatter mentioned O Manuel’s Iron Sun theory. That was when the Earth’s magnetic NP seems to get wanderlust and go East.

Almost as if it had become unleashed. I thought about this and it seems that the north hemisphere collapse of the sun was an indication of its loss of magnetic control. Through out all this the south hemisphere showed no change. I suspect this early collapse of n hemisphere of the sun is the result of the 2 year delay in solar magnetic reversals.

Looking forward to more info

Thanks

Answer from Nick:

It is wonderful to get such enthusiasm as in Kathleen’s question. At the same time both Harry and I struggled a little to quite understand what was meant.

Kathleen refers to a theory by Dr Oliver Manuel that the Sun is largely made of iron and that the solar system formed in a supernova explosion. This theory is not taken seriously by solar physicists and is in complete contradiction to current understanding. This is that the Sun is mainly made of hydrogen and helium with only a tiny amount of heavier elements such as iron. These heavier elements came from the contribution of exploding stars to the gas between stars before the formation of the solar system 4.5 billion years ago.

There is a huge amount of observations available on the Sun, especially in recent years from satellites that allow its interior to be probed with vibrations just as geologists study the interior of the Earth through seismology. There will be more on this on my forthcoming report on the solar physics conference that I attended recently at Palm Cove in Queensland. Although there are many details that scientists do not as yet know about the Sun, the observations agree with the current understanding of its structure and not with the idea of an iron interior.

Answer from Harry:

Kathleen asks two main questions: First, is it unusual that northern sunspot activity and southern activity can be out of synch? The answer is No, it’s not unusual. They are still two years out of synchronicity at present. This was also the case for at least the last four solar cycles. In fact, it’s interesting to muse on what keep the cycles in-synch?

Second: The polarity of the North and South magnetic poles of the sun are going to REVERSE quite soon (within next 12 months) – as happens every solar maximum. The process is messy and seems well advanced at present. We can’t call that a ‘collapse’ though – the reversal is fairly well understood. It doesn’t cause a reversal of Earth’s poles – which would be a BIG problem on Earth. Magnetic poles do wander around around – but that doesn’t mean Earth’s poles are about to reverse any time soon.

Harry Roberts is a Sun and Moon observer, a regular contributor to the Sydney Observatory blog and a member of the Sydney City Skywatchers.

I hope all this helps Kathleen. Please keep up your enthusiasm, but at the same time do not believe everything that you read on the web!

Nick Lomb

Edited and Posted by Kamal Jayakumar, Work Experience Student (Girraween High School)

Port Douglas, North Queensland, Australia
Wednesday, 14 November 2012

Earlier this year we told our friends in Sydney that we were going to Cairns to see the Solar Eclipse. Some thought we were mad; others said we were smart.

Yesterday, looking out of our Virgin airlines plane from 38 thousand feet, we wondered if we were indeed crazy, because the Queensland coast was covered in wads of cotton-wool clouds!

But, buoyed by the good wishes of all our friends, we hoped that we’d see at least a few minutes of this very special celestial spectacle. “Well”, said Dom, trying to console me, “it’s our holiday, so let’s enjoy it whatever happens.”
The briefing on Tuesday evening
“Beware of snakes and cow dung!” Melissa said with a smile. No one from our tour group smiled back. We had come prepared for mud and mosquitoes, not snakes!
Melissa, Education Officer from Sydney Observatory, our tour guide, had done her homework and visited the location for plan B, so we took her words seriously.

Why location B? Location A, ten minutes from where we were staying at Port Douglas, was a no-no. Clouds were about, and clouds were forecast for eclipse morning. So Melissa had to make a rapid change of plans. She consulted a weather forecast company that film makers consult, and they had directed her beyond the Great Dividing Range.
Cairns and Port Douglas are on the sea-front. Their weather is at the mercy of winds blowing in from the Pacific. Fortunately for us, the Great Dividing Range is inland from Port Douglas, and the mountains form a natural barrier for clouds rolling in from the sea.

So Melissa had to choose a location just past the shoulder of the Great Dividing Range. The place had to be reasonably flat, have a clear view of the east and be as close as possible to Port Douglas. She had personally driven around before we arrived, scouting for suitable places, and finally found one. There was only one catch. It was 160 km away.

Wednesday

So this morning we boarded the coach at the unearthly hour of 2 AM. Orion, bold and beautiful, was straight overhead. I considered it a good omen.

While we napped, Phil our coach captain drove very carefully on the Mulligan Highway that snakes its way over the Great Dividing Range. Two hours later, we reached the location in total darkness. The skies were wondrously clear. As we got off the coach and looked up, we oohed and aahed at the Milky Way spread out like a brilliant carpet overhead. The Southern Cross and the Pointers were to the south. Then, torches on, we carefully walked around cowpats and anthills to find a spot where we could set up our cameras. We noticed other cars there—at least 20 other astronomers had arrived before us.

The land was semi-cleared. To our great relief, resident snakes had taken off into the bush on hearing the footfalls of a platoon of men and women carrying torches, cameras and telescopes.
The spot was fairly level with low hills and a few trees which would be the foreground to the action. Venus was peeking over a mountain, so we set up our cameras aimed at her for we knew the drama would take place in that region.

Melissa had warned us we’d miss the first stages of partial eclipse, but it was a small price to pay for a good view of the rest of the extravaganza.

We started setting up our equipment—telescopes, cameras—in the dark. Each group chose a different vantage a point from which to view and photograph. We chose a spot from where the landscape would lend enchantment to the view and interest to our photos.

As the sky began lightening, the stars began to fade. The brightness grew; anticipation was palpable … and soon Venus vanished.
We talked to others in our group. Many had been to other solar eclipses—some had even been to four! Many said previous eclipses had been non-events due to bad weather. We were among a few first timers. We sure hoped we’d be first time lucky!

Slowly, one spot in the sky began to grow brighter. Someone called out, “Put on your solar glasses!”

The show had begun! All attention was focussed on the rising sun.

From the top left, the moon had taken a clean bite out of the sun!

Slowly the environs became darker. A bird called out. The air turned chill.
As the moon moved more over the sun, an unnatural hush descended. The vanished Venus and a few stars reappeared. The sun and moon slipped behind a tree giving me a unique photo of sun, moon and gum leaves.

We watched the sun becoming a crescent …

… and then a slim sliver. One of the kids called out, “It’s like a smiley!”

Eventually the sun was barely a thread of orange.

Then it happened! Total eclipse! A shout went up from the crowd!

“I can’t see a thing,” said someone.
“Take off your solar glasses!”
“Ahhhh! That’s better. Look at that!”

This was the climax of the drama. The sun and moon were in perfect alignment. What did it matter that this event can be explained mathematically in celestial geometry? It was a moment of bliss and magic—a poetic moment to remember with all its sights, sounds and feelings.

Two stages rapidly followed. First came Baily’s Beads—sunlight, like coloured beads, shining through mountain valleys on the rim of the moon—

—then total eclipse when the sun’s disk was fully obscured, but its corona was visible like a halo.

The two minutes of total eclipse felt like 40 seconds.

And then—oh wow! For a brief second the diamond ring flashed!

How we savoured the moment!
And all too quickly it was over. Slowly, the sun emerged from the shadow of the moon. The exposure of the sun began anew.

As the sun waxed, sunspots were clearly evident.

With the return of the light, we noticed how green the trees around looked.

The shadow of the moon over the sun was all but gone.

The show was over, but people were reluctant to go home!

Total eclipse as seen from Palm Cove beach, North Queensland. Picture Nick Lomb

The weather forecast was not good: clouds and rain were forecast for the North Queensland coastline for the morning of the eagerly awaited total eclipse on Wednesday 14 November 2012. Eclipse watchers who had gathered from all over Australia and from overseas for the event were worried and considered their options.

The keenest eclipse chasers, like those on the Sydney Observatory eclipse tour, rose extremely early and made a dash inland to places with better chances for a clear sky. Others stayed where they were and hoped for the best. I was attending a conference on solar physics (more on the conference in a future blog post) at the beautiful little tourist town of Palm Cove and had little alternative but to stay. In a way I was pleased to do so for I wanted to experience the excitement of not knowing what was to happen. And uncertainty and drama were certainly to be had in plenty on the morning of the eclipse!

Sunrise at Palm Cove beach. Photo Nick Lomb

As the Sun rose over the Coral Sea it could be seen despite plentiful clouds towards the eastern sky. Maybe totality was to be visible!

Clouds before totality with off-shore rowers possibly making a heroic attempt to reach a place with better visibility. Photo Nick Lomb

For a while any hope of seeing the eclipse seemed to be extinguished as thick dark clouds covered the Sun only allowing rays of sunlight (crepuscular rays) to be glimpsed below. By this time the whole beach was crowded with people excitedly waiting and hoping for totality. They were forced into a narrow strip of sand along the beach as the high spring tide associated with the phases of new and full Moon was coming onto the sand.

The Sun breaking through before totality gave hope to the assembled eclipse watchers on the beach. Picture Nick Lomb

As the time of totality approached the Sun started breaking through the clouds. With the Sun still low in the sky it cast long shadows. These shadows were somewhat sharper than usual for the light only came from a narrow part of the disc instead of the whole.

The partially-eclipsed Sun glimpsed with an appropriate filter through clouds, before (twice) and immediately after totality. Photos Nick Lomb

As the 6:38 am AEST time for the beginning of totality approached the Sun could occasionally be glimpsed through the clouds – obviously filters such as eclipse glasses were needed for safe viewing of the Sun at those times. Gradually, the dark disc of the Moon crept across the Sun and yet in the instants before totality there was still a small cloud in front of the Sun. Collectively, the assembled eclipse watchers on the beach were wishing for that little cloud to move away.

The two minutes of totality as seen in between clouds from Palm Cove beach. The sequence is from top left to the right and then bottom left to the right. Photos Nick Lomb

At the time of the first diamond ring and at second contact, that is when the Moon is just touching the inside edge of the Sun’s disc, a small cloud partially blocked the view of the Sun. However, as vehemently wished by the crowd, the cloud quickly moved away towards the north leaving a clear view of the corona.

As was to be expected, with solar activity near maximum, the corona appeared to fairly symmetrically surround the Sun. The corona is, of course, the Sun’s hot outer atmosphere with temperatures of a million degrees Celsius or more. One of the main concerns of solar physicists is to work out the mechanism by which it is heated as the regions below on the Sun are much cooler.

During totality I tried to see, both by eye and with low-powered binoculars, if there were any red prominences visible on the edge of the Sun. It may have been the thin haziness still in front of the Sun or my eyes but I could only just make out faint red regions at a couple of places on the Sun’s edge. Photographs later revealed extensive red regions though with a concentration at the places I had noted.

During totality the sky became sufficiently dim that the planet Venus could be seen above and the north of the Sun. Visibility of planets and bright stars is always one of the most spectacular feature of a total eclipse. I could not see other planets such as Saturn above and Mercury below the Sun though, probably due to the presence of clouds. The sky during totality was still relatively bright and in my subjective opinion appeared brighter than during the two previous total eclipses that I had seen.

As the eclipse ended with a spectacular diamond ring effect the crowd showed its joy for the sight that they had just experienced together by a spontaneous round of clapping.

I am pleased that I have successfully seen this, my third total eclipse of the Sun. Like everyone else at the beach, I was well aware of the sheer luck of having had a chance to see the eclipse despite the clouds. For the people on the beach at Palm Cove the clouds just added extra drama, while for others along the coastline such as those in the city of Cairns they caused deep disappointment.

I can hardly wait for the next total eclipse of the Sun!

Nick Lomb