Sunday, 30 November 2008

The Story of the Red Spirals (part 1)

I'll be writing a lot about the colours of galaxies in several different posts; here's Chapter 1, as it were. Kind of hoping the scientists will pop in occasionally and point out any glaring errors, and anyone who'd like to will give me feedback on the clarity and style . . .

A few years ago, Kevin was a PhD student at Oxford examining a new breed of galaxy. It's well known that there are two basic galaxy types: spiral and elliptical. It has also long been well known that spirals are usually blue, and ellipticals are usually red. The beautiful arms in a spiral galaxy are really density waves, like a traffic jam on a motorway. And like the areas of congestion, they don't necessarily move along with the stars - a car might cruise along at 70 m.p.h. for a few hours, reach the traffic jam, get very cross, but eventually get to the other side of it and continue on its way. (The spiral arms do indicate a lot about the galaxy - which way it is spinning round [except in the exceptions], how big the black hole in the centre is, etc.) This means that the environment the stars and gas live in is continually changing and disrupted - which triggers off star formation.

When stars are young, they are hot - and blue. Blue light has the shortest wavelength, and the highest energy. The equivalent, in sound, is a high-pitched note. (Sound and light both have wavelengths way higher and lower than what we can hear and see, but that's another story.) In any case, a blue colour in galaxies is a good indicator of a lot of heat and star formation.

Elliptical galaxies, on the other hand, don't have star formation. There seem to be two reasons for this. One is that the orbits of the stars are "radial" - they all go their own way - so there are no large-scale disruptions to trigger clouds of gas to condense. Another is that they seem to have run out of gas anyway. Come to think of it, one thing I don't know for a fact is whether these two points are related.

Ellipticals appear dull at first, but they're incredibly peaceful, beautiful sights. SDSS pictures usually show them as a clear gold or vanilla colour. They sort of "fade out" towards the edge, and have a bright core. Of course, this bright core often contains a supermassive black hole, such as in the case of the giant elliptical galaxy M87, which won't be the pinnacle of serenity. Elliptical galaxies are thought to be remnants of past mergers. They're generally found in giant clusters of galaxies, where mergers would be more likely to take place, and they are often larger than spirals. Mergers create massive disruption and trigger off spectacular star formation, which might use up all the gas free to form stars.

So "blue galaxy" came to mean "spiral", and "red galaxy" came to mean "elliptical". It worked fine before SDSS. Then we found it wasn't that way at all.

(Is it just me or is most science based on "People have always said that things are this way. But we have found it might actually be this way!"? After you've heard that in every lecture at university for a year or so, it gets highly tedious and you wonder if all the academics want to do is prove each other wrong, rather than make new directions for themselves. On the other hand, "Eureka!" moments are . . . somewhat immature. Curiosity and research and painstaking surveys have gone on for centuries. [There are always exceptions - apparently there are no budding fungi taxonomists left in the UK, but not all British fungi have been classified yet! Who's up for filling this niche?] Most of science now seems to be refining, redefining, extending and building on what we already know. Perhaps it's irksome because you wonder what there is left to do, other than prove someone wrong and then get proved wrong by the next upstart next year. Or perhaps I'm the only one irk-able enough to be irked. Let me know.)

Kevin was studying a strange new breed of galaxy: the blue elliptical. In other words, an elliptical galaxy which was still undergoing plenty of star formation. Because these are rare, and studying a few probably wouldn't tell us the whole story of what was going on, Kevin was aiming to find as many as possible. He spent a week sorting through 50,000 galaxies, categorising them into spiral or elliptical. His office-mate, Tom Zlosnik, wrote in the Galaxy Zoo Forum that he was getting through about one per second! It must have been a trial, though, and he doesn't recommend it. "Your PhD student," Chris said in a lecture, "will classify 50,000 before telling you exactly what you can do with the other 850,000."

And so Galaxy Zoo was born. But that's definitely another story.

Many of our classifiers wrote to us to ask us, "I've been noticing that spirals are usually blue and ellipticals are usually red. Have you noticed that? Is it just me? Why is that?" I wonder if they knew what an exciting question they were asking? I didn't receive any of these myself, so I can't tell you what the team answered. The most important thing was to encourage people to classify by shape, not colour.

The blue ellipticals featured heavily on the forum, particularly in the autumn. "Here's a blue elliptical for Kevin!" we kept grinning, often posting dwarfs, irregulars and fuzzy spirals. In fact, the way they were really extracting the data wasn't using that thread but using the computer to check the colours, and extracting the ones that came out as "blue" from the computer and "elliptical" from us. (And that is why you shouldn't classify by colour, folks! If you'd followed convention you'd have clicked "spiral" and all these would have been missed!) Kevin nevertheless kept us up to date, and made us a special thread about his paper.

And that turned out to be only some of the story. Because then people started spotting the opposite: red spirals. Which I'll write about next time. One thing was getting clear - studying a few galaxies in depth won't tell you what's going on at all! Only by examining galaxies in vast quantities, on the scale of SDSS and Galaxy Zoo, can you get a whole picture. It's like studying a few animals for years until you think you know all about them - and then going and looking at the whole ecosystem. Suddenly everything we saw seemed to be introducing new exceptions.

Saturday, 29 November 2008

A great start

Having written my first ever blog post, I've discovered two things . . .

1) Apparently it takes 7 hours to publish [some - not all] posts. I'm told that my last one is scheduled to appear at 00:33. Curiouser and curiouser . . .

2) There is a theme park somewhere called Galaxyland.

Oh well! :D

Update: 21:49 Aha! You click "post options", and it'll display the time it will be posted. You can change that. Now that worries me a little, because you could do quite a lot of time travel if you want it posted apparently a long way back in the past . . . Jurassic Park anyone?

An interesting primary school . . .

Welcome to my new blog, which I hope you'll find interesting. Thanks to my friends who persuaded me to set this up - blame lies particularly with Chris and Pat.

I was reminded today of a meeting I had with my mentor on my teaching course last year, shortly before they threw me off. "Now, Alice, in three weeks' time Bob [another PGCE student] has an interview, and part of that is to deliver a lesson for year 9s on their SAT papers. Now, be honest, I don't think you could do that, could you?" Too depressed to speak, I stared at the wall and shook my head. I wondered why I could explain any scientific concept to thirty-five children or one in a way that made their eyes light up; why they told me I was a good teacher and made earnest suggestions for other ways I could explain things and how I could improve the materials I gave them; how I could write posts about galaxies and astronomy and explain things to strangers over the Internet; but how I couldn't seem to do what the examiners wanted of me.

Things would have been different, I suspect, if I had trained at this school described today in The Independent. Two things leapt out at me about the article (besides the obvious happiness of the children and the parents). One was "no exams". None at all? Are exams the problem? According to the government, of course, they're the solution. "Testing children gives us a reliable indicator of where they are". (Unless they're having a bad day that day, not representative of what they can generally do. Unless the exam doesn't ask them the sort of questions they can answer well. Unless answering questions is not the only skill you need in life. Unless the examiner doesn't know what they're writing about. Unless the school is fed up with and contemptuous of this idiotic regime, and cheats.)

I've nothing against the idea of an occasional exam, as a challenge or as part of getting a qualification. What I am against is exams being the be all and end all. "They only take up a tiny proportion of the children's time in the classroom". Yes, but every single lesson has to be in preparation for them. Every lesson must have two learning objectives on the board (which must be measurable and achievable), and the more these relate to the exams the better. Why else do year 7 pupils arrive at secondary school with stories about having had to give up Art and Music and PE for year 6 to get ready for their SATs?

Do we need to get rid of exams altogether, or is it the general culture we need to change?

The other thing that struck me was the buzzwords around this school. "Its learning is child-led". "The Italian Reggio Emilia schools . . . put the learner at the centre of things". This might as easily have been said by OFSTED to promote personalised learning - a cringe-making fad state schools were caught up in when I began my PGCE, and which was a further box-ticking, time-consuming part of lesson planning. I really feel that the more talk there is around an organisation, the more false all these mission statements of theirs turn out to be, and the less gets done. Does the school buzz with these buzzwords? Or were they added to the article like a shiny paper bow stuck onto pretty wrapping paper, to make the article more marketable?

It's no good showing off how open-minded you are by saying "OK dears, the choice is yours, what do you want?" Otherwise, how will children learn anything? If you don't speak to them, how will they ever progress beyond baby-talk? What really mattered when the boy brought the rock in was that he brought in outside wisdom, luckily introduced by his grandmother. Sometimes the teacher could invent something to do; sometimes one - or more - or all - of the children will have something much better up their sleeve. Experiences like this will encourage them to keep their eyes open outside the classroom, rather than to learn the language the examiners want.

Because modern exams are largely focussed on getting children to write in the language required, rather than learning any facts (let alone expressing their own interpretations of such facts, or doing anything else with them). "It doesn't matter what they're learning, so long as they're learning something". The number of times I heard that. Not to mention, "He's got the answer exactly right, but we can't give him the mark because he's left out the key word".

To me, the truly special thing about Lewes New School is not their fancy phrases. To an extent, it's what the father says: "I wanted my children to love learning". But most of all, it can be summed up in one word: freedom.

A relative who works in a hospital spends far more time filling out forms for the government on how he will implement this policy or that, than actually seeing his patients. However, he's in their good books right now. He leads a project titled "A multi-disciplinary team-building exercise, open to all departments, with weekly reviews and performance indicators". What is it? Fantasy football.

You might want to try it.