Popular Australian Astronomer Honored For Service to Astronomy

Fred Watson… excuse me, Professor Fredrick Garnett Watson AM, was on this Australia Day 2010 appointed a ‘Member in the General Division of the Order of Australia’ – which is generally acronymized down to just AM. This honor was bestowed for ‘service to astronomy, particularly the promotion and popularization of space science through public outreach’.

Watson is a well known Australian identity after 10 years on ABC radio – answering many phone-in questions from the public, samples of which are captured in his popular book Why is Uranus Upside Down?  Another book Stargazer – the Life and Times of the Telescope has also sold well internationally.

Watson has appeared in a number of science television programs and is also a regular public speaker at forums such as Science in the Pub.  In 2006, he won the Australian Government Eureka Prize for Promoting Understanding of Science.

Since 1995, Watson has been the Astronomer in Charge of the Anglo-Australian Observatory in Coonabarabran, NSW. The AAO operates the Anglo-Australian Telescope and UK Schmidt telescopes on behalf of the astronomical communities of Australia and the United Kingdom. Currently the Observatory is funded by the Australian and British Governments to provide world-class facilities for British and Australian optical astronomers.

Born in England in 1944, Watson is considered a pioneer in the use of fibre optics in astronomy and spectroscopy – the subject of his PhD thesis gained at the University of Edinburgh in 1987. Watson apparently helped pay for his studies playing in folk bands alongside performers such as Gerry Rafferty and Billy Connolly – and apparently he used to have hair back then.

He has also combined a love of music and performance to communicate a passion for astronomy. As well as releasing his own CD An Alien Like You, he won an APRA award in 2008, for the Choral Work of the Year, being Star Chant, the choral fourth symphony of Australian composer Ross Edwards, for which Watson wrote the text.

Watson is currently participating in the international RAdial Velocity Experiment (RAVE) measuring the radial velocities and metallicities of up to 1 million stars in the Milky Way Galaxy. It is anticipated that RAVE will deliver a better understanding of the dynamics of the Milky Way, including determination of local escape velocity at different locations across our spiral galaxy.

And just to round off a not-too-shabby CV, he also has an asteroid named after him, Fred Watson 5691. Congratulations Fred – and have a great Australia Day.

Astronomy Without A Telescope – More Than Meets The Eye

Whatever hectic pressures may be at play in your life, you can always look forward to one quiet moment each week to contemplate the night sky in peace. I refer, of course, to when you have to take out the garbage – or as the Americans would have it – the trash.

Bin night observing receives less attention than perhaps it should in the astronomical literature. The chance to check the night sky once a week and at about the same hour gives you a chance to experience the difference between solar and sidereal time since the same stars now rise about 28 minutes earlier they did last week. And of course, you can quickly check the ecliptic for planets and for the Moon’s phase if it’s up.

Rarely, there may also be opportunities for educational outreach. A neighbor, aware of my astronomical tendencies, once asked me whatever happened to the Milky Way, which she recalled seeing as a child. I didn’t consider this a dumb question, since I remember seeing it as a kid too – it really is a ghost of its former self.

We had a useful chat about light pollution and then she said it. What’s that red one? Is it Mars? Not being on the ecliptic, it wasn’t – and the proximity of Orion’s Belt was a bit of a give-away. It’s Betelgeuse, I told her and she remembered the name from a Douglas Adams story and then we said good night. Astronomy advocacy in sixty seconds.

Betelgeuse image reconstructed from interferometry measurements in infra red. Credit: Xavier Haubois (Observatoire de Paris) et al. (An APOD for January 6 2010).

But I hate that color thing. I’ve spent years unsuccessfully squinting to make out the allegedly red color of Mars or the yellowish tinge of Saturn – while as soon as I get someone interested in the night sky they start picking out M type supergiants. I’m not color blind and I manage just fine in the daytime. But bin nights have always been a strictly black and white affair.

That is until now. I saw that Mythbusters episode about how early sailors wore an eye patch so that during a cannon battle they always had one dark-adapted eye. Allegedly, this was so they could go into the powder room for more ammunition without having to light a match.

As you probably know it’s all about the rods and the cones in your retina. The cones carry three types of photopsins – that preferentially absorb red, green and blue, while the rods carry the all important rhodopsin – which enables you to see in very dim light, though just in black and white. Apparently, it takes rhodopsin 30 mins to recover from light bleaching, but only nine minutes for the photopsins. Nine minutes is all I need to decant the kitchen scraps, grab the recyclables and wheel the bins out to the kerb. Then patch off, I can enjoy an opsins-optimized, monocular view of the night sky and yep, there’s a little hint of orangey-red. Awesome.

You should try it. In fact I’d be grateful if everyone would try it and spread the word. So the next time someone in my street asks… Who’s that nut taking out his garbage dressed like a pirate? There’ll be someone nearby to explain… It’s OK. He’s an astronomer.

Astronomy Without A Telescope – Getting Orientated

We’ve all been there. You’ve met someone nice – but for some inexplicable reason, they don’t get astronomy. So how do you start gently introducing them to your life’s passion (about astronomy that is) without scaring them away?

First it’s important to recognize that not everyone will be instantly in awe to learn you own a 14-inch Schmidt-Cassegrain with four speed microslew. Weird, but there it is. And it’s going to be a challenge getting that special someone to drive out to a lonely spot in the wilderness for some proper dark sky viewing – and don’t even mention that there’s such a thing as naked eye astronomy.

Start with the Sun – it’s big and it’s obvious and everyone gets that it rises in the east and sets in the west. Well, that of course means that the Earth is actually spinning from west to east. And heck, you’re an astronomer, so you’re bound to know your cardinal directions on familiar ground – so just point. We are spinning that way.

And if you are in the right part of the lunar cycle – you might comment, on one of those romantic moonlit evenings, that last night at this time the Moon was there – and tonight it’s shifted a bit to the east. Don’t dwell on it – just put the idea out there. The next night let them note that – hey, it’s moved even further east! They might even notice that it’s filled out a bit – but this is not the time to introduce them to the word gibbous.

What’s happening is that they are starting to make their own astronomical observations. All you have to do is to find an opportune moment to pull the background together.  If the Earth spinning from west to east, that means that from a perspective in space – at least from above the North Pole – it’s spinning anti-clockwise. And the fact that the Moon inches further towards the east day by day means it’s orbiting the Earth anti-clockwise.

Hopefully you’ve captured their interest enough to carry on with the fact that actually all the planets orbit the Sun in that same anticlockwise direction – indeed, even the Sun spins in that same direction, once every 28 days. A quick mention of the theory that the whole solar system formed from a gas cloud that spun down into a disk – and it’s probably time to move on to another conservation topic. This is not the time to introduce them to the conservation of angular momentum. Pace yourself.

From here – a wealth of discussion could arise in the days to come. Your potential new partner might ponder whether all the planets spin in the same direction – to which you can reply well mostly, except for Venus and Uranus – and then you’re away talking about planetary collisions. Or, maybe you’ll be asked whether all the planet’s moons orbit in the same direction – to which you can reply well mostly, but there’s Triton that goes the wrong way around Neptune – probably because it came in from the Kuiper Belt. There’s a Kuiper Belt now?

Good luck.

Dreamtime Meteor Impact Found with Google Earth

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Duane Hamacher a PhD student from Australia’s Macquarie University found an ancient meteor impact crater in a remote location of the Northern Territory by searching Google Earth and following clues from an ancient dreamtime legend told by the indigenous Arrernte people.

Mr Hamacher reported to the Sydney Morning Herald and other Australian newspapers that the Arrernte people’s legend about a star that fell into a waterhole called Puka in the valley where Kulaia, the serpent, lived – has led to the discovery of the ancient crater, which the research team he is part of propose to name Puka.

Guided by details of the story, Mr Hamacher searched an area about 130 km southwest of Alice Springs, in the Finke National Park on Google Earth.  He found what appeared to be a bowl-shaped depression. His suspicions were confirmed when he visited the site with a team of geophysicists and astrophysicists, who found evidence that a popular tourist location in the national park called Palm Valley contains the remains of an ancient impact crater.

“We found shocked quartz, which is only produced by a substantial impact and its presence in the rock samples and the morphology of the structure are the major indicators that Palm Valley is a crater,” Mr Hamacher said.

The ancient landscape around Alice Springs has preserved several impact craters, notably Gosses Bluff Meteorite Impact Crater, which can be seen from the ISS and is thought to be the result of a bolide impact 145 million years ago. Much more recent is the Henbury Meteorites field, a collection of over 13 small craters formed by a meteor breaking up before impact just over 4,000 years ago. Several tonnes of iron-nickel meteorite have been recovered from this site. And if you are wondering – Wolfe Creek crater, central to the plot of a misspelled Australian horror movie, is in Western Australia.

Gosses Bluff crater seen from the ISS

A date for the impact that caused the newly found Palm Valley crater has not been reported, but is certainly millions of years in the past. Although the local people could not have observed the impact directly, Mr Hamacher proposes that their intimate knowledge of the land may have led them to surmise such a cause and to integrate this knowledge within their local dreamtime legends.

Mr Hamacher expects more impact craters may be found in this way. “We found stories with descriptions of cosmic impacts and meteorite falls related to places in Arnhem Land – we assume there are more meteorite craters out there and science doesn’t even know about their existence yet,” he said. Mr Humacher is reported to be expecting to publish more details of this find in a future edition of Meteoritics and Planetary Science.

Wolfram Alpha – A Handy Tool for the Casual Astronomer.

A schematic map of the Internet.

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We are not quite at that point where you can ask your computer to swing over to the Orion Nebula and take a few shots for next weeks’ astrophotography competition – oh and a cup of Earl Grey, hot, thanks.

But every day seems to get us that little bit closer.

If I want to know where Mintaka is in the night sky, I could start up a planetarium software program like Stellarium, or the legion other planetarium programs and web-based sky mapping sites to choose from.

The Orion's Belt stars (including Mintaka). Credit: http://www.freewebs.comBut, being a ‘just point in the general direction and muck about until you find it’ type of telescope user, I’m much more interested in an objects’ alt-azimuth position from my particular location, rather than trying to set my scope to right ascension, declination settings. Seriously, I am holding off on starting my astrophotography career until those Go To computers can make a proper cup of tea.

Anyway my point is, even with all these great information resources around, things are still a bit all over the place. Wouldn’t it be great if there was one place where you could go to find out – well, anything? Wolfram Alpha seems to be taking steps in that direction. It’s kind of a front end interface drawing on a huge virtual warehouse of databases.

As well as the basic search engine, there’s a wiki sideline to all this, notably a set of Wolfram Astronomy demonstration projects here, including a downloadable 3d celestial sphere, a planet database and why not a simplified model of the Big Bang.

Advanced Celestial Sphere (Wolfram Demonstration Project). Credit: Jim Arlow.And it knows where you live. At least it knows where I live, I guess from my IP address, so I save a step there. Wolfram Alpha can tell me Mintaka is set to rise at 6.01pm local time, it’s 720 light years away and it will set at 6.07 am. And any time I like, I can just hit refresh and get its alt-azimuth position updated in real time. It can do the same for the planets and for the ISS too. Not too shabby.

Also useful for the casual astronomer, if you type in your city, it will give you a weather report – and even a population count if you like. And from there you might find yourself straying further off topic. For example, I now know there are 202,185 people alive named Steve – which is only 1 in every 1,173 people. Hah.

And if you do type in Tea. Earl Grey. Hot.? It says Coming right up. Can’t wait.

An Astronomical Perspective on Climate Change

Ice cores and deep sea bed cores provide the best available record of changes in global temperature and CO2 content of the atmosphere going back 800,000 years. The data shows a clear periodicity in global temperatures which is thought to be linked to the Milankovitch cycle.

Back in 1920, Milutin Milankovitch, a Serbian mathematician, proposed that fine changes in Earth’s orbit around the Sun could explain an approximately 100,000 year cycle in glaciation seen from geological evidence. The tilt of the Earth’s axis swings slightly over a 41,000 year cycle – the eccentricity of Earth’s orbit moves from almost circular to more elliptical and back again over a 413,000 year cycle – and overlaying that you have not only the precession of the equinoxes, which is an inherent wobble in the Earth’s axial spin over a 26,000 year cycle, but also a precession of the whole of Earth’s orbit over a 23,000 year cycle.

Ice core data does show a rough concordance between glaciation and the synchronicity of these orbital cycles. Even though there’s no significant change in the mean amount of solar radiation reaching the Earth over the period of its annual orbit – the orbital changes can lead to increased polar shadowing and cooling.

Once ice does start advancing from the poles, a positive feedback loop can develop – since more ice increases the albedo of Earth’s surface and reflects more of the Sun’s heat back into space, thus reducing mean global temperatures.

ice coreIt’s thought that what limits the ice advancing is increasing CO2 in the atmosphere – which can be measured from trapped bubbles of air in the ice cores. More ice formation leads to less exposed land area for photosynthesis and silicate rock weathering to remove CO2 from the atmosphere. So the more ice that’s formed, the more CO2 accumulates in the atmosphere – which causes mean global temperatures to rise, which limits ongoing ice formation.

Of course the opposite is true in an ice-melting phase. Ice melting also follows a positive feedback loop since less ice means less albedo, meaning less solar radiation is reflected back into space and mean global temperatures rise. But again, CO2 becomes the limiting factor. With more exposed land, more CO2 is drawn from the atmosphere by photosynthesizing forests and rock weathering. A consequent drop in atmospheric CO2 cools the planet and hence limits ongoing ice melting.

But there lies the rub. We are in an ice-melting phase of the Milankovitch cycle now, where the Earth’s orbit is closer to circular and the Earth’s tilt is closer to perpendicular. But CO2 levels aren’t declining – partly because we’ve chopped a lot of trees and forests down, but mostly because of anthropogenic CO2 production. Without the limiting factor of declining CO2 we’ve seen in previous Milankovitch cycles, presumably the ice is just going to keep on melting as the albedo of the Earth surface declines.

Projected changes in coastlines with 170 metre sea level riseSo you might want to rethink that next coastal real estate purchase – or hope for the best from Copenhagen.

The View from Down Under

Something that baffled me throughout my childhood, growing up in Australia, was the frequent references to the Man in the Moon, in children’s books and other popular media. I just couldn’t see it.

Only in my adult years have I put two and two together and realized that all those references were made by people from the Northern Hemisphere.

South of the equator we really are down under, even in astronomical terms. All the stuff you can see in the night sky around the celestial equator and the ecliptic we can see too, but it’s all upside down (or from our point of view, right side up).

So the lunar maria you see on the Moon’s surface, we can see too, but upside down none of it looks anything like a human face.

And Orion’s Belt? Nope, don’t get that either. obeltconstWhat we see is an asterism we like to call ‘the Saucepan’ because what you see as a dagger hanging off a belt, we see as a handle rising from a pot.

We’ve also got our own down under Aurora Australis, although you’d have to105412main_High_res_jan05 climb a mountain in Tasmania, or even better catch an icebreaker to Antarctica, to see it.

But look, I’m envious. You’ve got a pole star, Polaris, which we never get to see. And you get a good view of the Andromeda Galaxy, which just barely peeks over our northern horizon around summer.

Down under, we have to use the Southern Cross to find the southern celestial pole. The Cross contains some of the southern sky’s brightest stars. During the winter months when it’s high in the sky, it’s generally the first group of stars to become visible after sunset, along with the nearby Pointer stars – which are actually Alpha and Beta Centauri.

The Southern Cross is kite-shaped and if you draw a line out from the kite’s long axis and another line out from between the Pointers, those two lines meet at the southern celestial pole. From there, just drop your hand straight down to the horizon and you are pointing due South. Cheaper than a compass.south

We also have a couple of dwarf galaxies to look at, being the Large and Small Magellanic Clouds. OK, they are much smaller than Andromeda, but they are also a lot closer and hence appear much bigger. To the naked eye, they really do look like a couple of faint, wispy clouds.

For most southern sky observers, the Magellanic Clouds and the Southern Cross are circumpolar, slowly spinning around the southern celestial pole each night without ever setting.

You probably know that the story about how water spirals down the plug hole in opposite directions on either side of the equator is just urban myth. But it is the case that while stars in the Northern Hemisphere appear to spin slowly around Polaris in an anti-clockwise direction, all our stars spin around the southern celestial pole in a clockwise direction.

It’s true – fair dinkum.