Star formation is hidden from view by dust surrounding the sites where it occurs. Optical light is blocked by dust, but we are able to see the dust itself thanks to submillimetre and far-infrared radiation that still escapes. Until recently we did not have the technology to map such active, hidden regions at these wavelengths. Planck and its sister telescope, Herschel, are changing that using ultra-cold detectors in the vacuum of space, positioned far from the Earth.

These images of star formation in Orion and Perseus show us two very different regions of our galaxy. The Orion molecular cloud complex is huge – if you could see it it would take extend all the way along the well-known constellation – and the above 15×15 degree snap of part of it, shows us prestellar cores and structure in the cold dust that makes up the region. (You can see the full image here). You can see the same part of the sky in other wavelengths using this Chromoscope link.

The image below shows how this Planck image compares with the stars of Orion’s belt, and shows the location of the Orion Nebula and the Horsehead Nebula (the two lower bright spots). The Planck image is bigger than you might think. The left-hand, monochrome image is the visible DSS map (i.e. the naked-eye shot) and the right is the Planck map. The central image shows the two overlaid. You can see a great river of material that seems to almost flow out of the Orion Nebula in the bottom, centre part of the image.

If you look at just the 850 micron image, in green below, you are essentially seeing cold dust in the Orion cloud complex. You can make out some amazing detail. Fine clumps and points in this wavelength are showing us objects known as prestellar cores. These dense points in the cold dust map are likely to be about to collapse and form stellar systems. These maps will be used to determine the mass and dimensions of such objects to help us understand the origins of such systems, including our own Solar System.

The map of Perseus (below) shows an even larger region. This map is 30×30 degrees and you can see even more cores and structures in the dust. This region is not as active in terms of star formation, and this gives it a more ‘even’ feel with less very bright sections and less dominant physical features. You can also see the plane of our galaxy as the broad, busy section in the top half of the image.

Perseus is less distinctive than Orion in the night sky but here is a similar optical (DSS) image shown blending into the Planck map of the region. The Pleiades are visible in the bottom-left. It is interesting to see how this striking, young clutch of stars is much less pronounced to Planck’s eyes. Only the small portion of dust surrounding it remains visible and it just forms one knot in a vast structure spanning either side of the cluster itself. A bright reflection nebula is seen near the centre of the image as being bright red in the Planck map. This is nothing to do with dust but is seen in red as synchrotron emission, a result of hotter interactions from the same radiation that lights up just that part of the nebula is the visible image.

These images reveal the amazing sights and science that Planck will deliver. Curiously these images are a kind of side-effect of Planck’s primary goal, which is to map the Cosmic Microwave Background. It just happens to make these detailed maps as it sweeps around the sky – and as a star formation astronomer, I’m very pleased about that indeed.

[Read more in ESA's news article for these images. ]

• Red: 750 – 620 nm
• Orange: 620 – 590 nm
• Yellow: 590 – 570 nm
• Green: 570  -495 nm
• Blue: 495 – 450 nm
• Violet: 450  -380 nm

Here I’ve used the figures given by Wikipedia (sourced from catchily titled the CRC Handbook of Fundamental Spectroscopic Correlation Charts). The same ranges are shown on the image below.

You might notice how narrow the Yellow and Orange bands appear and, if you’re a keen colour cadet, that Indigo isn’t on the list at all. The rhyme I learned at school was Richard Of York Gave Battle In Vain – seven colours in the order of they appear in the spectrum. In fact Indigo used to lie between 450 and 440 nm. That is a really tiny waveband. Why? Because most people cannot tell you the difference between indigo and either blue or violet. Essentially the colour is more akin to one of those Dulux paint charts from the DIY store that it is to any of the ‘real’ basic colours. You may as well include biscuit, lavendar and lime in the spectrum.

Indigo was originally included in the spectrum by Isaac Newton, the man who formally discovered that light is split into different colours. Using a prism he showed that white light was a mixture of what he saw as seven basic hues, including indigo. He chose seven because he was attempting to make the colours of the Universe fit in with what he was as a numerological pattern appearing elsewhere.

Isaac Newton was not what you would recognise today as a scientist. He believed in alchemy (the idea that you can convert one element into another, e.g. lead into gold) and was extremely mystical. He was quite eccentric and didn’t even publish his most famous works until long after he had finished working on them.

At the time when he split light into a spectrum there were seven known planets in the Solar System. there were seven musical notes (do ra me fa so la and te) and of course there are seven days in a week –  a Biblical determination. So seeing his spectrum as being made of seven colours was quite a natural idea and he made it fit. The image at the top of this post shows his original colour circle – musical notes are shown around the edge, matching certain colours.

It got me wondering how many colours I would have divided the spectrum into if I had been the first to properly measure it. Ten colours, to match my decimal upbringing – maybe 5? Perhaps I would have added octamarine? It would be interesting to get children to divide up the spectrum themselves and then compare it with Newton’s result. How many colours can you see?

The story of Newton ‘inventing’ indigo is one I heard a while back but dismissed. It came back to my mind last night after it was mentioned on BBC Radio 4′s The Unbelievable Truth. They also mentioned another Newton tale which I shall finish up this post with. Newton spent a short part of his life (1689-1690 and 1701-1702) as a Member of Parliament for Cambridge University. During his two-year tenure he is only recorded to have made one speech: he asked for the window to be closed because he was cold. I think that tells you a lot about him.

Pluto is so small and distant that the task of resolving the surface is as challenging as trying to see the markings on a soccer ball 40 miles away.

Plans are now being made to use Hubble’s new Wide Field Camera 3 to make further Pluto observations prior to the arrival of New Horizons in 2015. Advanced Hubble images will help the New Horizons team to take better shots of the dwarf planet when the probe arrives, and to make the most efficient use of time as it explores the Pluto-Charon system.

The new images have also been combined into a great video showing the current surface of Pluto rotating. You can find a small (iPhone-friendly) version right here or you can grab the HD one from the NASA site by clicking here. Read the full NASA press release here.

Thanks to Mike Brown (@plutokiller) for pointing this out via Twitter.

The swirl of cloud heading in from the southeast is bringing more snow tonight and tomorrow for much of the country as the big freeze continues. You can keep track of the snow via the user-generated #uksnow map from Ben Marsh.

If you’re new to the idea of the celestial sphere then you have to imagine the sky depicted as a really big sphere, with us sitting inside it. The sky stays stationary as the Earth rotates inside it. So the North pole of the sky, Polaris, lines up with the Earth’s North Pole and so on. If you are sitting at the North Pole then Polaris appears directly overhead all the time. If you’re sat at the equator then Polaris is at the horizon and the celestial equator rolls more or less overhead.

Over the course of a year, the Sun will appear to oscillate just above and below the celestial equator (by about 23 degrees), because of the tilt of the Earth’s axis (see above). However, on any given day it will seem to stay in same place, circling the sky following an approximate line of latitude. This is what is depicted below. The path of the Sun at each solstice is drawn and the celestial sphere. In each case the longest path is the Summer solstice and the shortest is the Winter solstice. As you move from the equator to the pole, the difference between the paths drawn by the Sun gets larger until near the pole (at about 70 degrees latitude) there is no Winter track because the Sun is below the horizon all the time. You are now inside the arctic/antarctic circle.

There are a couple of interesting points raised by these images. Note that at the equator, the Sun does not always go directly overhead. In fact this only happens at the equinoxes (the time in the middle of the two plotted tracks). In the 50 degree latitude diagram, there are little faint circles depicting the Sun below the horizon – these indicate that it is still contributing to some sort of twilight – which above 50 degrees lasts all night during the Summer solstice! This is why astronomy can be so difficult in midsummer here in the UK, for example, but not in Southern France.

The diagram showing the solstice at the pole lets you imagine the Sun spiralling closer and closer to the horizon as the year goes by. Six months from perpetual midday comes perpetual midnight, each day the Sun creeping lower and lower before skirting the horizon and then disappearing at the equinox.

Something I had never though of, but which is pointed out in the Wikipedia article, is that until 20 degrees latitude, the Sun is either in the North or the South depending on the time of the year. This is counterintuitive to most of us who are used to the Sun always being in the South (for the Northern Hemisphere) or the North (for the Southern Hemisphere). For example, in the UK, south-facing views are sunny ones. However below 20 degrees latitude in the Northern Hemisphere, the Sun can arc through the sky in the North, not the South, because of its oscillating position around the celestial equator. This becomes obvious in these diagrams but I had never thought about it before.

All of this is as much geometry as it is astronomy but I think it is interesting. These excellent diagrams do a great job of giving you feel for the why the seasons are so different and why the solstice happens (they also have added detail in the types of tree shown).

The 2009 Winter Solstice occurs at 17:47 on December 21st (the exact publication time of his blog post), the 2010 Summer solstice will be June 21st at 11:28.

The rusty red material you see is dust and it contains within its filaments and structure, some 700 protostars ready to burst into life. The thick dust in this region had, until now, totally obscured all the amazing content. The blue areas are places where stars have already formed and are now illuminating nearby hydrogen gas.

This image has been keeping an officemate of mine busy for quite some time already. Identifying the 700+ protostars and myriad other objects in this image – which is only one of hundreds of images yet to come – is a big challenge for astronomers working with Herschel data. I can’t help but wonder if the answer to this data-rich problem may lie somewhere in the Zooniverse.

You can find more on Herschel on the ESA website, and you can read more about this particular image via this ESA link. This image was released alongside a new website called OSHI (Online Showcase of Herschel Images) which although a bit sparse right now, is worth bookmarking for the future.

This means that each year I have spent probably too much time thinking about nice, simple physics demonstrations that vaguely relate the the holiday season. One of my favourites is the one I concocted to try to demonstrate the principles of teleportation using LEGO.

The only way I can think that Santa might be able to deliver so many presents in just 31 hours (think about it) is that he must be able to teleport – unless he can time travel. If he delivered all the presents by parking the sleigh, descending into the house and laying them out then it would take him thousands of years to get the job done.

To demonstrate teleportation in a lecture theatre turns out to be quite easy – and fun. You need some LEGO and a bench with a dividing screen on it. After a brief preamble explaining the basics of teleportation you ask for two volunteers to act as ‘supercomputers’. You give one a small LEGO model of Santa and ask them to disassemble the model and put the pieces in a pot. Then the pieces are passed to the second ‘supercomputer’ who has to reassemble the model with only the pieces and instructions from the first volunteer. This is done under a time limit for a bit of extra excitement. They will almost undoubtedly not reassemble Santa correctly and this can be very funny by itself.

It illustrates rather nicely how much information storage/transmission would be required to teleport something as they do in Star Trek. There is also the issue of the nature of the LEGO blocks themselves. If you pass the same pieces over then you have to explain how that would be done. Alternatively you can use other identical pieces but then is that really the same Santa that you started with?

The image at the top of this post is from the IRAS satellite and it shows our galaxy, the Milky Way, in the far infrared. It is quite beautiful and in fact goes much deeper in detail. What you’re seeing is a sort of heat map of the galaxy. The structures and details shown in the infrared are very different to those seen in optical light. Objects that are invisible to the human eye can shine brightly in infrared, such as warm cores surrounded by think blankets of dust.

So with all this buzzing about in my head you can imagine my delight at borrowing the department’s infrared camera! I was able to take the handheld thermal digital camera out and about in Cardiff for the afternoon and then take it home too. I took shots of just about anything that might be interesting in the infrared and posted them up on Flickr.

Nemesis!

Roughly every 30 million years something very bad seems to happen – life on Earth seems to die in vast quantities and a large percentage of all Earth’s species go extinct. Why do these mass-extinction events occur? Not sure – but it does seem to have happened with a reasonably regular interval for over 250 million years.

One hypothesis for this is that there is something ominous circling around us, at the edge of the Solar System. Some think it could be a large planet, other suggest a dead star – it has been given names like Planet X and Nemesis. Whatever it is, the theory goes that it is orbiting our Sun in a highly elliptical fashion. Once every orbit it plunges very close to the Sun, just scraping the edge of the Solar System: the Oort Cloud.

The Oort cloud is home to countless rocky bodies – it is the home of many comets – and such a massive gravitational nudge would send potentially thousands of these objects hurtling into the inner Solar System – one of which might hit us and cause a catastrophic global disaster. This might what killed the dinosaurs, and it’s possibly what will kill us.

Magnetic Switch

Since the mid-nineteenth century humans have been monitoring the Earth’s magnetic field. The same magnetic field that guides migratory birds and makes a compass work also protects us from harmful radiation from the Sun and gives us the beautiful Northern Lights. But here’s the thing – it is gradually weakening. According to some researchers, this could mean that something is about to change.

We also know – and this where it gets disturbing – that the Earth’s magnetic field has historically flipped over from time to time. In fact this usually happens every 250,000 years. It has been almost 800,000 years since the last flip so perhaps we’re overdue. Of course no one was around to witness the last one and so we don’t know what effect it would have. Things could get very ugly though.

If the magnetic field that protects the Earth did flip it would mean that somewhere along the way we wouldn’t be protected from space for a while! We might be bombarded with harmful radiation or cosmic rays. The lovely aurora would perhaps be slightly more menacing if they gave you cancer. If the flip is sudden then it would wreak havoc on the world’s electric systems – potentially frying them.

The Singularity

We are now able to make ever-smarter machines. What happens when we make a machine that is smarter than us? The answer surely is that it will be able to built an even better, smarter machine and that in turn will build an even better one too. Within a few cycles we will be faced with a machine so clever that we seem puny and irrelevant by comparison. The world could quickly be controlled and organised by such a machine and we will have ended our reign here.

We are also extending the human lifespan faster all the time (in the West) – what happens when we extend it by more than a year each year? We will then live indefinitely. Technological progress advances exponentially. This means that world-changing advancements come along at shorter and shorter intervals – eventually you reach a mathematical singularity, at which point things can no longer be thought of the way they used to.

The theory goes that some singularity is coming in the next century and although it may not be quite as we imagine it, it will possibly end the world as we know it. It may bring an end to our lives as we know them – in the machine case for example – why not download ourselves into super-intelligent machines and go onto bigger and better things? At our current rate of progress we will make more progress in the next century than in the past 10,000 years. The world as we understand it will surely cease to be.

Irradiated

Gamma Ray Bursts (GRBs) are distant but gargantuan explosions that take just a few seconds and release more energy than the Sun will in its entire lifetime! Some are 100s of times more powerful than that. Needless to say, you don’t need to be very close to one of these things to be more than a little singed. It could be almost anywhere in our galaxy and still devastate the planet.

There are other ways to be irradiated: the Sun could go nova, releasing massive quantities of dangerous material and radiation; a stray pulsar could accidentally spin around and fry us like an massive, errant laser pointer.

However it might happen, it remains remotely possible that in a brief instant the Earth could find itself totally irradiated on one side. Every living thing, every molecule of anything would be vapourised and instantly! Half the population – more or less – would be gone in a microsecond. And they’re the lucky ones. If you’re unfortunate enough to live on the other side of the Earth during this high-energy blast then you have the pleasure of gradually rotating around into the radiation – if it is still there. Worse still you could experience the awful, apocalyptic nightmare that is a shockwave of plasma – made up of every living thing from one half of the planet – sweeping across the world, incinerating everything as it goes.

Andromeda

We’ve  all heard the old wives tale about the Sun dying and swallowing up the Earth as it becomes a red giant, right? Well let me tell you you don’t need to worry about it. That will take 6 billion years to happen – that’s ages! Especially whn there’s something much worse heading for us much faster.

The Andromeda Galaxy, the Milky Way’s friendly galactic neighbour and virtual twin sister is heading right for us. Pulled in by gravity, Andromeda and the Milky Way are on a collision course and  in 2 or 3 billion years Andromeda will rip our galaxy apart like cotton wool. Shockwaves will ripple through the two galaxies, triggering supernovae and star formation at an incredible rate.

The Solar System will be lucky to survive such an event. Gravitational forces could tear us apart, radiation could fry us to a crisp or if we’re really unfortunate we could be gobbled up by one of two very big black holes as they coalesce and merge.

Snowball Earth

Periodically, many times over the course of the Earth’s history ice has covered the world and then gone again. I’m not talking about ice ages – no this is something even more dramatic. 600 million years ago the Earth was a giant snowball – entirely covered by ice. It also happened 100 million years before that and over two billion years ago. This ‘Snowball Earth‘ is the result of a runaway cooling effect where the ice covering the surface of the planet increases the reflectivity (or albedo) such that a lot of the incident radiation from the Sun bounces back into space, thus cooling the planet further.

As man-made climate change warms up the Earth, key processes may shut down due to changes in the freshwater/salt water balance – the gulf stream, the ocean currents. If this happens and the poles are cut off from sources of warm air or water, then they may refreeze rapidly and the runaway ‘Snowball’ process can begin.

Evolving Out of Style

With all this talk of things that might happen in millions and billion of years it is probably prudent to mention that we almost certainly won’t be around anyway. If by the end of the world, you mean the end of civilization or the end of the human race, then even looking a million years ahead is foolish.

Even the most well-adapted and long-lived species seem to only last a few million years or so before evolving out of style. The ones that do are not exactly like us – crocodiles, sharks, cockroaches. The human race, like any other, is subject to the environment around it and will evolve and adapt with it. It only takes one big volcanic eruption or viral outbreak to change our circumstances dramatically.

In a million years we could have become plankton-eating aquamen or tree-loving, hairy cannibals. We may not even live on Earth anymore…

Big Crunch/Rip/Freeze

Our universe has been around for 13.7 billion years – Earth has been around for just over 4 billion. We’ve been here for a few hundred thousand – depending on what we you call ‘we’. If we do manage to secure our existence indefinitely – perhaps by uploading ourselves into machines or spreading ourselves far and wide enough into the cosmos – then can we really be here forever? Time it seems could be eternal but also it could not.

Following the Big Bang – the beginning of the universe – we can either live in an ever-expanding universe that eventually rips itself apart (the Big Rip), an ever expanding universe that gradually slows down (Big Freeze) or a universe that reaches some extremely large size and then begins to fall back in on itself (Big Crunch). It all depends on how the Universe is made up and how much dark energy there is.

If we’re heading for a Big Rip then eventually there will be no Universe left as we understand it – so we die. If it’s a Big Crunch then everything ultimately smashes back together and time end – so we die. If the Big Freeze happens then sooner or later all the energy in the universe gradually becomes so diluted and spread out that nothing energetically useful can ever happen – everything freezes out – (thoughts, movement, calculations) – so we die.

Heisenberg Uncertainty Principle

Nothing is impossible – just highly improbable. As fans of the Hitchhiker’s Guide are aware. That is what Heisenberg ended up stating about the Universe thanks to quantum mechanics. It is possible, though not very likely that a giant cat will appear one day and give the Earth a lovely hug and magic up some tea and cake. It is also equally unlikely that one day a giant death ray will appear and destroy our whole planet.

Given enough time – say an infinitely long time – eventually each of these things will happen. The problem is that since we already exist, it doesn’t matter if something good pops into existence alongside us. If something bad randomly blurts out of the vacuum – even for a brief moment – and destroys us then that does matter. The longer we hang around, the more chance there is for something like that to happen.

It isn’t likely, but is worth thinking about.

When you begin to consider such figures in relation to each other then your whole world changes! For example the Iraq War ($3000 billion), worldwide spend on advertising ($320 billion) and the Internet porn industry ($97 billion) are seen in stark contrast to the defense budget of Russia ($11 billion) and the global gift card market ($29 billion).

NASA’s annual budget was just about $17 billion for 2009 and the entire annual UK STFC budget is about $1 billion.

This image comes from Information is Beautiful, which if you’re not reading you should be. It is a fabulous blog collecting together (and creating) some amazing and insightful data-art.

[Information is Beautiful's Billion Dollar Gram]

As the time of impact approached on Friday, the web began buzzing with tales of how NASA was going to ‘bomb the moon’ – I even ended up arguing on Twitter about it with a random user. It seems that LCROSS’ end-of-days finale was too much for some to take – with much criticism of ‘littering’ and ‘polluting’ the Moon going on. This all despite the fact that, as Stuart Lowe and Chris North point out, this sort of thing happens to the Moon all the time – albeit with rock and not space probes.

As it happens, the spectacular plume was not visible from Earth as was hoped – disappointingly nor was it terribly visible from the NASA live feed. This led some to say the mission has failed but again this is another case of science being misunderstood. A small plume was seen, even if it wasn’t as big and bright as hoped – and NASa got lots of data. No doubt they will reveal before too long what they have – or have not – uncovered.

They have quick post up showing that a plume was at least ‘just’ visible – the optical image is shown above – and I await further results from the LCROSS team in the coming weeks.

More importantly though – if they do find evidence of water hidden under the Moon’s South Pole – why is this important? Well if we want to send people back to the Moon and then beyond into the Solar System we need to start thinking about actually going and living on the Moon. We need bases in space – and the Moon is a good place – or space travel will just be too expensive. Water is heavy and carting it about with us around the Solar System will be difficult. If we have a supply of it on the Moon that we can mine then we need to know where it is and thus where to start thinking about putting our first base.

If there is water to be found on the Moon then it becomes even more interesting and relevant to mankind’s space travel agenda and to its science agenda in the coming decades. Well done to the LCROSS team for a successful smash-down!

Servicing mission 4 (SM4) will launch on Monday from Cape Canaveral (2pm EST) this coming Monday (May 11th). The shuttle Atlantis is performing the mission. There will be another shuttle on standby, acting as a lifeboat because the astronauts have no other means of escape.

The team will be giving Hubble quite an overhaul. They will be replacing a unit the controls Hubble’s communications with the onboard science instruments. Several spacewalks will replace all six gyroscopes and install new batteries. This life-extending repair mission also involves new guidance sensors, thermal insulation and a new de-orbit mechanism for when Hubble is moved at the end of its life. It is hoped that the whole exercise will give Hubble another 5-10 years delivering science.

The astronauts will also try to repair Hubble’s out-of-commission instruments, the Space Telescope Imaging Spectrograph (STIS) and the Advanced Camera for Surveys (ACS). STIS stopped working in 2004 and ACS failed in 2007. Brand new intsruments Wide Field Camera 3 (WFC3) and the Cosmic Origins Spectrograph (COS) will be installed. WFC3, is a visible, infrared and ultraviolet light camera. It should improved the sensitivity of Hubble some 10-30 times.

It is perhaps most interesting to note that if the mission is a total success then Hubble will literally be better than it has ever been! It would have six functioning scientific instruments as well as brand new stabilisation and operational components. Not bad for an observatory that is now older than the undergraduates coming into our astrophysics degree programme.

Fingers crossed for Monday!

[Hubblesite SM4 page, NASA SM4 page]

The European Space Agency’s (ESA) Herschel Space Observatory  has the largest single mirror ever built for a space telescope. Herschel’s mission is to collect long-wavelength radiation from some of the coldest and most distant objects in the Universe. In addition, Herschel will be the only space observatory to cover a spectral range from the far infrared to sub-millimetre – an ideal regime for my own area of study: star formation.

Herschel will be launched along with Planck, ESA’s microwave observatory which will study the Cosmic Microwave Background. Planck is designed to image the anisotropies of the Cosmic Background Radiation Field over the whole sky, with unprecedented sensitivity and angular resolution.

Cardiff University is heavily involved and will be holding launch events on the day, including a live video feed (with nibbles). Both Herschel and Planck can be found on Twitter. I will attempt to liveblog from Cardiff on the day, and I’m sure that many others will do the same around Europe.

I find that reading papers outside of my own academic field is quite compelling and often sparks the imagination. The problem of course is knowing which papers one should read if you’re not inside the system. After a few weeks this website should begin to show the emerging favourites in any field.

It’s also interesting to simply see what gets talked about. As the data piles up, it will be possible to filter the papers into different topics or types. It might, for example, be useful to see what astrophysics papers are most discussed in a given month, or which biology paper has risen fastest through the ranks this week.

The engine behind the site periodically looks for tweets that contain both the word ‘arxiv’ and an arXiv.org paper identifier (such as 0102.3456). You can see a list of recently detected tweets on the site itself. In this way it will pick up anyone mentioning an arXiv URL or someone who tags their tweets #arxiv and includes the paper id – two things that I often see. It also therefore keeps the idea global – you don’t have to tweet in English.

The statistics and top-tens are worked out democratically:

• If a paper is tweeted 4 times then it is ranked 4x higher than a paper that is mentioned only once.
• I place no restrictions on multiple mentions by the same user at present.
• One can mention more than one paper in a single tweet. This will give each paper a single vote.
• Mentioning the same id code more than once in a tweet does nothing.

If it continues to look interesting, I have every intention of adding more detailed trends to the site as time goes by. For now, I just need data – and by that I mean tweets! Start tweeting about your favourite papers now! If you have any thoughts on the kind of data you’d like to se displayed, then let me know in the comments.

I’m a bit confused about what to call this new site. ‘twarxiv’ came to mind, but is entirely inaccessible to outsiders! Anyone have ideas? If you can think of a good name, or have any other suggestions about arXiv on Twitter then please leave a comment here or contact me @orbitingfrog.

During next week’s Moonwatch event at Cardiff University, I’ll be manning a stand showing people how to use Twitter, Google Earth and the Internet to find satellites in the night sky. As well as showing them how to use Heaven’s Above, I’ll also be outlining my own projects OverTwitter, LookUp and Satellite KML.

I’ll also be talking about .Astronomy, Galaxy Zoo and how to view interesting and alternative wavelengths on Google Sky. I’m going to be busy!

Since most of my readers are in the US and Canada, you can download my poster about my own projects rather than fly all the way to Cardiff next week. You can also download this handout explaining these projects and providing links.

If you you are in the Cardiff area, then you’ll need to register to attend our Moonwatch event because it is full up! However, if you have a telescope of your own, I would suggest holding your own smaller Moonwatch event locally. Invite the neighbours round and have some drinks while you show them the Moon!

The new initiative is a follow-up to the highly successful Galaxy Zoo project that enabled members of the public to take part in astronomy research online. But whereas the original site only asked members of the public to say whether a galaxy was spiral or elliptical, and which way it was rotating, Galaxy Zoo 2 asks them to delve deeper into 250,000 of the brightest and best galaxies to search for the strange and unusual.

The best way to learn about Galaxy Zoo is to go and have a go! You can also follow them on Twitter  - where you might even catch the news in advance of the general public.

Does the sun leave an ecliptic path through any other constellations or just the zodiac constellations? – Blossom

The answer is interesting and is also a good way to begin revealing astrology for the money-grabbing scam that it really is.

The Sun passes through thirteen constellations on its path through the sky (called the ecliptic). In traditional astrology the heavens are divided into twelve even sections of a circle. In reality the Sun spends different periods of time in each constellation. The boundaries of these constellations are entirely artificial of course. They were standardised by the International Astronomical Union around 1930, as one of the group’s first official acts.

At present, the Sun resides in the following constellations (or star signs) during the following periods of the year:

Aries: April 19th – May 13th

Taurus: May 14th – June 19th

Gemini: June 20th – July 20th

Cancer: July 21st – August 9th

Leo: August 10th – September 15th

Virgo: September 16th – October 30th

Libra: October 31st – November 22nd

Scorpius: November 23rd – November 29th

Ophiuchus: November 30th – December 17th

Sagittarius: December 18th – January 18th

Capricornus: January 19th – February 15th

Aquarius: February 16th – March 11th

Pisces: March 12th – April 18th

But it is more complicated than that! Traditional astrology is all about the relative locations of the various planets within the twelve signs. Problem is, the planets do not follow the ecliptic exactly. Each planet is inclined at an angle to the Sun in the Solar System and so they draw out slightly different paths.

In addition to the 13 constellations listed above, the planets pass through 8 more. So in a sense Cetus, Corvus, Crater, Hydra, Orion, Pegasus, Scutum and Sextans are also astrological signs. This means that there are 21 astrological signs of the zodiac. You might want to ask an astrologer how they interpret a planet in one of these ‘extra’ constellations. What does it mean if Uranus is in Scutum? Sounds painful.

Astrology is an ancient tradition that sprang up in many cultures because the stars’ apparent ability to predict certain events (crops, weather, etc). In the modern era, astrology is a con. It not something that one might believe in through tentative evidence or testimony, it is simply a fiction perpetrated by those who are able to make money from it. It is based on the principles of cold reading, gullibility  and wishful thinking. It may well be that there are things out there in the universe influencing our lives on Earth. However, the geometric happenstance that one star might look to be in a particular place at some point during your life is not going to affect your mood, your luck or your love life.

You might as well try to gain insight into your existence from the way you parked your car.

Of course, since this object has not cleared its orbit, I suppose it must actually be an exodwarfplanet.

Dark Matter & Dark Energy - [Read More about Dark Matter and Dark Energy]

Dark matter is hypothetical matter that feels no effect from electromagnetism, so we cannot see it. Its presence can only be inferred by the gravitational influence it exerts. Galaxies do not rotate as expected by Newtonian dynamics. The Coma cluster of galaxies also has properties that gravity cannot explain.

Dark energy is similarly mysterious, but even less easy to understand. It is a kind of energy that permeates the whole universe, driving it apart and causing it to expand. These two things together purportedly make up 96% of the content of the Universe.

Physical cosmologists study dark matter and dark energy with great interest. Change their names to ‘gravity not doing it what it should’ and things can look slightly different. A branch of physics labelled MOND (MOdified Newtonian Dynamics) tries to explain the observational evidence without adding in unknown forms of matter and energy. There are also many scientists who feel that ‘dark energy’ gives the wrong impression and that this stuff might be normal matter that we simply don’t see for some reason.

So either gravity is wrong or matter is. That is quite a dilemma for astrophysicists to resolve.

Gravitational Waves - [Read More about Gravitational Waves]

Now, I’ve gotten in trouble before for having a beef with gravitational waves, so I’ll try to be kinder here. Gravitational waves are fluctuations in the curvature of spacetime which transmit the energy of gravity and propagate its effects through the universe. Light’s energy is transmitted to us by fluctuations in the electromagnetic field, this would be an alternative spectrum of waves, detectable by completely different means.

The study of gravitational waves has received a nobel prize (1993, I think?) when they were indirectly detected in a binary system containing a pulsar. The orbital energy in the binary system was seen to decay in exact accordance with the theories of gravitational wave physics.

Einstein’s general relativity explains gravitational waves very well  - in fact if gravitational waves don’t exist there is a big problem. The problem comes along when you find out that no one has ever detected a gravitational wave. People have been trying for quite some time.

I often see graphs which explain this lack of detection. Basically gravity waves may just be too subtle to be detected by current methods. The answer is to build larger, more complicated observatories (in space preferably). The plans are already made. If they don’t find them then, either a new idea gets floated, or a new graph gets drawn and an even bigger detector is created.

I hope they find them before too much money gets spent!

The Higgs Boson - [Read More about the Higgs Boson]

The Large Hadron Collider (LHC) had to be shut down for a little while and so its main target: the Higgs Boson remains an unknown and unverifiable character.

Imagine you had a really nice cake. You studied this cake for a long time and you managed to figure out exactly how it was made. You could tell me the proportions and nature of the original ingredients, the length of time for which it was baked even the exact colourings used in the icing. What you don’t know though, is the type of spoon that the cook used. Without knowing this you will never truly have understood how the cake was made – and you will never managed to recreate it. If it turns out that there was no spoon then your whole theory falls apart!

The Higgs Boson is that spoon.

Without the Higgs Boson the whole framework of our understanding of particle physics is incomplete. The LHC should be able to detect it. If it can’t, then there may be a problem and the standard model of patricles will need to be reconsidered. If it is found, then we would have a complete understanding of the particles that make up the Universe. That would be profound and powerful. We may find out one way or the other in 2009.

Panspermia - [Read More about Panspermia]

How did life on Earth begin? Well one idea is that it came to our little rock from space. This notion is called Panspermia and it is actually as old as modern science. Early musings on evolution in the 18th Century considered that the original germs came from space.

Fred Hoyle (who died in 2001) and Chandra Wickramasinghe (who is now based in Cardiff’s astrobiology centre) were early proponents of Panspermia in its modern form. They also suggested that lifeforms continue to enter the Earth’s atmosphere, and that they might still cause epidemics and provide new genetic material for the planet.

The problem with Panspermia is that it solves a complicated problem (how did life spontaneously begin on Earth) with an even more complicated solutiom (how did life spontaneously begin elsewhere and then travel across billions of miles of interstellar space). For this reason, many need a lot of convincing about the idea.

String Theory - [Read More about String Theory]

String Theory is the name given to a branch of physics and maths that aims to describe the Universe in terms of multi-dimensional vibrating strings. No this isn’t Pratchett. It would be a way to combine the as-yet irreconcilable theories of quantum mechanics and general relativity – this is something of a holy grail in modern physics.

String theory is a broad name for a collection of theories – some of which disagree with each other – but all of which boil down to the principle described above. The trick is, you cannot disprove string theory. You would need an experiment so large and powerful that it would require orders of scale larger than our Solar System. We are a very, very long way from achieving this.

The strings themselves would be so fantastically small as to be possibly prohibited from measurement by nature itself. Lengths and timescales so minute that we could never measure them.

One hope for string theory is that we may see evidence of hidden dimensions when the LHC begins operations. However this could also be evidence of other things, and not necessarily a win for string theory.

For these reasons, many consider string theory not to be science, but rather mathematics. One day in the distant future we build the right apparatus and experimentally test this outlandishly cool idea. It may be right – or it may just be a mathematically self-consistent way to explain particle physics and gravity.

Summary

Popular ideas are not always good ones, nor are they necessarily bad. The work being done to advanced science in the five areas above is extremely important. However so is the work being done to provide alternative ideas and theories. Nothing in science is proven until it is proven.

How We Got Online

We begin with a quick history lesson. This is merely to help place into context, some of the facts and figures I will be detailing.

1991: arXiv begins.
1993: Mosaic graphical web browser puts people online, at home.
1994: Netscape Navigator is released becomes standard web browser until Microsoft launch Windows 95 with Internet Explorer built in. Browser wars ensue.
1995: NASA ADS begins online.
1998: Google begins, rise of the search engine.
2000: Dotcom bubble bursts, paves way for new generation of technologies including blogging, social networking etc.
2002: Web becomes ubiquitous in Western culture. This date is obviously only approximate.

It’s All About Numbers: ADS

The ADS receives around 3,000,000 readers a month. These are papers actually read, not including hits that result in no followed link.

Over 1,000,000 unique users every month.

Around 30,000 regular users, who access the service more than 10 times a month.

Fig 1 – The way ADS is used. Data taken from January and February 2008. Shows the things people do with articles they find on ADS.

Fig 2 – The way ADS is found. Data taken from January and February 2008. Shows the ways that users find NASA’s ADS.

It’s All About Numbers: arXiv and astro-ph

arXiv receives around 1,000,000 website hits every working day.

More than 900 papers are submitted to astro-ph every month.

Submitting your paper in the final minutes before the 4pm deadline (US Eastern Time) will increase your citation rate.

Living in the United States increases your chances of achieving this effect.

Fig 3 – Shows the way different journals have adopted astro-ph by looking at the percentage of papers from those journals which are also published on astro-ph.

Fig 4 – The characteristic way that a paper gets read. Initially papers are read on astro-ph when they first go up. After they have appeared on ADS, users tend to prefer to read the refereed article there.

Fig 5 – Typical example from Monthly Notices of the Royal Astronomical Society. Papers published in 2007, that were also published on astro-ph received 2.4x as many citations as those that were not. This factor is called the astro-ph Impact Factor.

Fig 6 – Variation of the astro-ph Impact Factor over time for four different journals. Note that the trend is for astro-ph to become more influential as time goes by.

Fig 7 – Impact of astro-ph on Citations for Different Journals. These data points are the averages over the past six years.

Why is astro-ph Influential?

Dietrich (2008a) propose three mechanisms for the impact of astro-ph and other online archives.

Open Access – Because the access to articles is unrestricted by any payment mechanism authors are able to read them more easily, and thus they cite them more frequently.

Early Access- Because the article appears sooner it gains both primacy and additional time in press, and is thus cited more.

Self-selection Bias – Authors preferentially tend to promote (in this case by posting to the internet) the most important and, thus, the most citable articles.

You Can Game the System

Papers appearing at the top of the astro-ph listing each day are seen by more people and thus cited more often. The last submission before the 4pm (Eastern US) deadline appears most prominently in the next mailing and will be listed first. Thus, if you time it right, you can try to place your paper near to the top of the list! The result is that some authors tend to promote their most important works and, thus, most citable articles, by placing them at prominent positions. This not a strong effect but it is also not uncommon.

Being based in the USA the submission deadline preferentially puts those authors at the top of the listing whose working hours coincide with the submission deadline. This is also only a slight effect, and according to Dietrich (2008b) it is more than cancelled out by the author placement effect described above.

In Summary

In a few years, use of astro-ph will be almost universal. The astro-ph preprint archive has had a marked affect on the way academic papers are read and cited. Statistics appear to show astro-ph having an increasing impact, probably as more people use the service more often with improved Internet access.

ADS as a global service introduces biases toward submissions at particular times of day. astro-ph does not diminish readership for publications, nor does it significantly increase use of the ADS. Journals which use astro-ph the most do not see a significantly better impact compared with those that use it less. But all journals see an impact.

Submissions purposefully made near the deadline, artificially increase citation counts but cancel out geographical bias toward North America.

References

Dietrich, J. P., 2008a, “The Importance of Being First: Position Dependent Citation Rates on arXiv:astro-ph”, Publications of the Astronomical Society of the Pacific, Volume 120, issue 864, pp.224-228 – [Link]

Dietrich, J. P., 2008b, “Disentangling Visibility and Self-Promotion Bias in the arXiv:astro-ph Positional Citation Effect”, Publications of the Astronomical Society of the Pacific, Volume 120, issue 869, pp.801-804 - [Link]

Henneken, E. et al., 2006, “Effect of E-printing on Citation Rates in Astronomy and Physics”, Journal of Electronic Publishing, vol. 9. - [Link]

Hennken, E. et al., 2008, “Use of Astronomical Literature – A Report on Usage Patterns”, eprint arXiv:0808.0103 - [Link]

Metcalfe, T. S., 2005, “The Rise and Citation Impact of astro-ph in Major Journals”, Bulletin of the American Astronomical Society, vol. 37, p.555-557 - [Link]

The Cardiff HAlf metre Newise Telescope (CHaNT) officially opens today. The new, half-metre telescope is big enough to see Andromeda’s companion galaxies, to study the red spot on Jupiter and to see stars which, frankly, I never thought I’d see from Cardiff.

…it would be possible to view a postage stamp being held up at Castle Coch from the roof of the university’s physics building in the city centre around six miles away.

It will be used by undergraduate students studying astronomy and astrophysics and we are hoping that some of those students will take some amazing images through the telescope in the coming months. A new observatory website will pop up by 2009 to showcase our new toy, and I will give details here on Orbiting Frog when that happens.

CHaNT has an interesting design. It is ‘not-quite-newtonian’ in that it has a spherical primary mirror and flat secondary mirror. Corrective lenses are then placed before and after the secondary mirror to account for spherical aberration. This means that the telescope is smaller than an equivalent newtonian design and thus is even more powerful than it appears!

The opening of the new telescope will take place today, Friday 24th October at 3.30pm in the School of Physics and Astronomy, Cardiff University. You can read more about the telescope here. You can also follow CHaNT on Twitter, if you’re so incline.

View Press Release | View BBC News Article

Instead of golden syrup you could use treacle or corn syrup: something gloopy and messy. For alcohol you can use almost anything from spirits to rubbing alcohol. If you’re a kid, please ask whoever is in charge before raiding the drinks cabinet (this is generally a good rule in life).

You will be putting all of these into one glass, so find a tall one that is reasonably straight-sided. The more angled the edges of the glass are, the more of each liquid you will need as you go along – this could get tricky. You’ll need about one sixth of a glass worth of each liquid, as shown above.

Start with the glass containing the syrup and carefully pour the dishwashing liquid into it. You want to pour down the sides of the glass if possible, this will help stop the two liquids mixing. For these two it should be easy enough as they are both fairly thick. Let the glass stand for a moment and you should see that the two liquids make layers in the glass.

Now we add the rest of the liquids, in the order shown in the image at the top. Pouring down the side of the glass may not be enough to prevent these remaining liquids from mixing. It helped me to use a teaspoon. Hold the teaspoon inside the glass just above the surface and pour gently into the spoon, allowing the liquid to pour over the sides. In this way, the liquid you are pouring is placed on top of the existing ones much more gently. Be careful and pour slowly and you should be fine. You can always practice your pouring in another glass if you want to.

Hopefully you will end up with a nice, layered glass of different coloured liquids. Why? Well it is all to do with density – the mass per volume – of the liquids. Liquids at the bottom have higher densities than those at the top. All liquids have different densities as well many other properties. We can explore some of them using our layered glass.

Take a chopstick, or similar stick-like object and insert it into the glass. Don’t disturb the glass too much though. See how the chopstick looks now. Each liquid bends the light coming through the glass in a different way. This is related to the density but is actually a property of all materials called the refractive index. In general the refractive index increases with density. It is a measure of how much light is bent as it passes through a material.

We can also explore two more properties of liquids: viscosity and miscibility. Take hold of the chopstick and stir the glass up. Stir well, but try not to spill the contents. Watch and feel how the liquids mix.

You’ll notice that it is very hard to mix the syrup and that you can also feel the washing up liquid dragging against your stirring. This is because heavy liquids tend to be viscous. Viscosity is the measure of a liquid’s resistance to you changing its shape. The syrup is highly viscous, i.e. it resists your chopstick very strongly. The water, alcohol and oil offer almost no noticeable resistance at all, by comparison. This is because they are all similarly viscous and we are all used to how water ‘feels’.

After you stop stirring the glass, wait a few moments for it to settle down again. Watch it during this time and you will see it appear to organise itself. Miscibility is the measure of how well two substances mix. Water and alcohol are miscible because they mix together just fine. You can see that they do not separate out again after you stop stirring.

Water and oil are immiscible. This means that they do not mix. It doesn’t take long after you stop stirring for the oil to float back to the top. Would you say that the washing up liquid is miscible with any of the others? I found it hard to tell because both it and the syrup were so viscous I could not stir them up very easily!

Liquids, and their many properties, shape all sorts of things in the world around you. Refraction, density, viscosity and miscibility are important in our everyday lives.

Anyone who has had to clean oil-based paints off a brush with water knows something about miscibility. If you have tried to hook something out of a pond or swimming pool who have experience the frustration of refraction. You also know that you float in the sea, this is because of the difference in density between the salt water in the sea and the water in your body. Have you ever had to wait for ketchup to slowly pour out of a bottle because of its high viscosity?

In astronomy you can see some of these properties in action. The planet Jupiter has a series of coloured bands running across its surface. The different fluids that make up Jupiter’s enormous mass do not mix well because of their make-up. The hydrogen- and helium-based fluids are thought not to be miscible and this is part of the reason that we see the striking bands or colour on the planet’s surface.

Refraction and density are a big problem when observing through a telescope. The air becomes unevenly heated and this creates patches of the sky with higher refractive indices than others. Pollution also changes the refractive index of the air. The result is a fuzziness that astronomers call the ‘seeing’. Because of this, astronomers prefer to put telescopes high-up and away from cities with their hot buildings and smog.

Viscosity is important in simulations of planet formation. Disks around young stars are made up of different materials and if they get dense enough they will become highly viscous and drag against the force of gravity as it tries to force them around the central star. The result is that parts of the disk could be dragged inward and this could greatly determine the formation and evolution of planets.

You can click on any of the top-twenty words to see a few of the tagged posts. This is a really nice proto-tool (currently it is listed as being version 0.2), and I look forward to seeing how it develops.

I wonder if we will soon see ‘spacebuzz’ making its way up the list?

To volunteer to make your mark and record your very own episode of this epic, podcast endeavour, you only need to register on the newly launched 365 Days of Astronomy website. After that, click on ‘Join In’ and follow the instructions.

365 Days of Astronomy represents a great challenge and it should be brilliant to tune in each day and hear something completely new and interesting. It is vital that as many people, from as many parts of the world get signed up. So ask your school, youth group, badminton club, football team, decorators and anyone else to take a look and think about having a go.

Podcasting is easier that you might think and to be part of this exciting global initiative would be something you’d remember forever. So whether you’re 1 or 100, 365 Days of Astronomy is waiting for you. The website will also be giving tips on podcasting and will be doing everything they can to make sure the process is reasonably simply and easy to do.

To do this yourself, or to expand upon and modify this script, download the workflow file here.

To set this up to run everyday, open it up in Automator. Click ‘Run’ to test that the script works (warning: it could take a minute or two to process, but this ok). You might also want to to change the folder into which the picture files will be saved. Then chose File -> Save As and change the type to iCal Alarm.

When you save the file in this way, Leopard will open up iCal and let you change the usual event options. You can select the time the script should run and the repeat cycle (I’ve set mine to repeat each day at 9 a.m.).

Alternatively, you can save this as an application and run it when you like in the normal fashion. In fact you can do quite a few things with it, I’d be interested to know what people come up with.

Flickr user FlintstoneStargazer captured all 110 of the Messier Objects between March 7th and August 6th this year. They have all been compiled into a big mosaic. This is very cool – anyone else ever tried anything like it?

Finally my paper studying the Ophiuchus star-forming region is done and dusted and has been accepted for publication. Thanks to one of my intrepid co-authors, that paper appeared today on astro-ph, the preprint paper listing for astronomy and astrophysical theses.

We re-analyse all of the archive observations of the Ophiuchus dark cloud L1688 that were carried out with the submillimetre common-user bolometer array (SCUBA) at the James Clerk Maxwell Telescope (JCMT). For the first time we put together all of the data that were taken of this cloud at different times to make a deeper map at 850 microns than has ever previously been published. Using this new, deeper map we extract the pre-stellar cores from the data. We use updated values for the distance to the cloud complex, and also for the internal temperatures of the pre-stellar cores to generate an updated core mass function (CMF). This updated CMF is consistent with previous results in so far as they went, but our deeper map gives an improved completeness limit of 0.1 Mo (0.16 Jy), which enables us to show that a turnover exists in the low-mass regime of the CMF. The L1688 CMF shows the same form as the stellar IMF and can be mapped onto the stellar IMF, showing that the IMF is determined at the prestellar core stage. We compare L1688 with the Orion star-forming region and find that the turnover in the L1688 CMF occurs at a mass roughly a factor of two lower than the CMF turnover in Orion. This suggests that the position of the CMF turnover may be a function of environment.

It is a study of star formation and prestellar cores, the objects that precede protostars. You can access the online abstract and get more information at arXiv.org or simply download the PDF from Orbiting Frog.

Telescope Limiting Magnitude = Visual Limiting Magnitude – 5*logd + 5*logD

, where d is the aperture of the human eye and D is the aperture of the telescope. So to give some examples, let’s consider a normal sky where the visual limit is around Mag 5.5 and you have a little 3-inch refractor telescope. We’ll use 3mm as the aperture of the human eye.

Telescope Limiting Magnitude = 5.5 – 5*log(0.003) + 5*log(0.07) = 12.3

So with a small refractor you can see down to a limit of about Mag 12. Pluto however is at Mag 13.8 so this would not suffice. Here is the maths for my own situation. Last night the sky was so dark I could make out Mag 7.0 stars, this is my visual limit and it is about right for very good observing conditions. The telescope I am using has a 9cm aperture.

Telescope Limiting Magnitude = 7.0 – 5*log(0.003) + 5*log(0.09) = 14.8

This puts Pluto into the realms of the feasible, which was great news since Pluto from my location is well above the horizon and unobscured by light pollution. Also, this week I have set myself the goal of observing all the planets, and Pluto – just for fun.

Pluto can currently be found in Sagittarius at the painfully dim magnitude of 13.8. Along with its sister body Charon and two satellites Nix and Hydra, it is a very cold, dark and far away place. Even the best images ever taken of Pluto reveal little more than a patchy ball of rock. I was unable to take a picture myself, far too dim, but Googling reveals a handful of amateurs have succeeded.

The image above is taken from Mauna Kea and the one below comes from an amateur named Bill Dirk.

If you want to try and see Pluto, I can now recommend a few things to help you along. Firstly, check that you have dark enough skies. This isn’t trivial, I have rarely had as good conditions as last night. Unless you have a very big telescope (more than 15cm) you’ll find Pluto is beyond your reach in anything other than exceptional skies.

Secondly, know where to look. Using the Meade with a good calibration means that getting into the general vicinity of Pluto is fairly easy. you need to know your stuff if you’re using a regular, manually guided telescope. Whatever happens, you need tracking, other wise the objects you find will vanish before you can see them at all.

Thirdly, get a good map of the planet’s location and memorize the patterns of stars around it. Once you’re looking at a star-field in the eyepiece, it will look the same as every other star field, unless you know what you’re after. Most planetarium software will give you this, the trick is figuring out the field of view you will be looking at through the eyepiece. I recommend using the 12DString FOV Calculator.

Finally, have patience. This will take time and several attempts. Even if you do find it, if you’re like me you’ll feel the need to verify everything twice anyway. But I think it was worth it!

Having finally seen Pluto I am now compelled to complete my planetary observation collection. All of the planets are visible during the night at some point from my current spot. I will not be here much longer so I need to get out and see them all. I have never yet seen Neptune or Uranus and I have only seen Mercury twice.

I’ll report back later in the week.