Tuesday 15 October 2013

A galaxy of cells, an NHS supporter and a wonderful world

"I am a galaxy."

Well, that's definitely one way to begin a book. And I've been learning quite a bit about the process of writing books in the last few weeks.

Recently I attended my first book launch: Marcus Chown's What A Wonderful World. It took place in a bookshop near Holland Park. There were vast tables of books, a great many about travel and cookery. There were a few tables of wine, juice, and nibbles. And there was Marcus, helping get everything ready. His publicity agent, Ruth Killick, remarked to me, "I've never worked with anyone as lovely as Marcus. Most writers don't pitch in and help set everything up the way he does!"

There was an enormous cake . . .
 . . . and Marcus did quite a lot of book-signing and talking to people . . .

Among the guests were Simon Singh and Nigel Henbest - who had a nasty bump on his head from a recent zero gravity experience, and who I was able to thank for writing The Space Atlas with Heather Couper, my second childhood astronomy book that really got me hooked. There was also Marcus's editor Neil Belton. In their speeches, they told the story of how Neil pushed Marcus to "go outside his comfort zone" and write a book not about his usual physics and astronomy, but about "everything": biology, evolution, geology, economics - generally how human society, and our planet and Universe, have come to be the way they are.

As part of their launch, they're doing a blog tour, and I'm today. (I suppose it would sound silly to say "Sorry I didn't have it ready this morning, but I had a headache yesterday"?) Various bloggers are writing with their impressions of the book. That is, I'm told, a very effective way to find readers!

It's a lovely huge chunky book. Marcus has been having fun giving it to astronauts and the Clangers. We begin with cells. Each of us has more cells than a galaxy has stars - hundreds of billions. As Marcus tweeted a few hours ago, "Your body will assemble 30 million new cells in the time it takes to read this tweet. Each has the complexity of a medium-sized city." We find out what a cell is made of and why they should be so complex - and what a huge leap it was that they should start joining together and forming multicellular organisms.

The interesting thing about this chapter, and other early chapters, is that they . . . well, not exactly contradict, but don't really quite match what I learned in GCSE and A level biology. I found myself arguing. "Yes, that's called the phosopholipid bilayer. Hang on, it's not always the case that men have XY chromosomes and women have XX. Wait, we get our energy from oxygen linking up with carbon, not hydrogen. Or as well as hydrogen? Wait, I must check that! How exciting!" (That's the rocket-fueled baby in chapter 2!) So, I was frowning and biting my lip, but . . . well, if there's one thing I found out from teaching, it's that the science curriculum does not actually have much in common with real science. So a lot of what I've learned in school biology might need some relearning. (The chromosomes knowledge has come from conversations with trans* friends on Twitter, but this is an exception.) Werner Heisenberg used to joke that he had learned physics the wrong way round - particle physics first, classical physics second. And I, too, learned about galaxies from Galaxy Zoo long before doing any actual astrophysics courses about them. Marcus wrote about how, knowing what he considered nothing about various subjects, started from scratch and phoned up experts. It's good to learn things, or re-learn them, in a new way. So I'm very glad my school knowledge has been so brilliantly challenged.

I was particularly interested to find out what Marcus would write about money and capitalism, given his activism to save the NHS! Marcus is part of the NHA Party (as am I) and most of his tweets are related to this. (We've been on demonstrations together and he, I and his wife Karen, who's a nurse, were going to bandage one of the lions in Trafalgar Square, but the police stopped us.) Initially I raised my eyebrows to read about a sweet ideal of money: that a fisherman can catch eight fish at the same time as an axemaker can make four axes, and if they tried to do each other's tasks they would do less well at them, so they trade. I needed not have worried. We follow history through the word "salary" coming from "salt", an early form of currency, and progress to all the dangers and the suffering caused by unchecked capitalism today - including the 2008 crash; the hypocrisy of developed countries imposing a "free market" on developing countries, ignoring their own economic histories; and the idea that the market is too unpredictable and complex to understand, how this has become an easy way out of trying to regulate it, and how some organisations deliberately make it more opaque than necessary. I wish my old economics teacher had read something like this - she extolled the virtues of the Tories and the horrors of any market regulation at us lesson after lesson . . .

One of Marcus's favourite activities is collecting together surprising facts, and this book is bursting with them! Slime moulds have 13 sexes, DNA in all species is so similar that we share a third of ours with mushrooms, we age more slowly at ground level than above, that the advantage that modern humans may have had over Neanderthals was sewing (I say "might; I don't feel I know enough to be sure), and that the Universe may have been a giant hologram. And this great favourite:

It definitely is a wonderful world, and I've been having great fun reading this book. Thanks for including my blog in your blog tour!

Tuesday 8 October 2013

"A Passion for Science" and Ada Lovelace Day

Ada Lovelace Day, created by Suw Charman-Anderson, is a yearly celebration of women in science, maths, engineering and technology. It started with pledges to write about women in STEM on a particular day - here's my attempt from 2010 (yes, I should have done more since!). It's well documented, including by experiments, that women still face barriers in these fields, and Ada Lovelace Day is one of the initiatives to challenge this and to celebrate unsung heroines.

If you want to get blogging on Ada Lovelace Day, just pick one (or more) women in STEM to write about on 15th October this year and let Suw know what you are doing! I may not be able to as I'm writing something else on 15th October, so apologies for that.

This year, Suw's put together what looks like a fantastic event. I'm going, and maybe I'll see you there. It's at 6pm at Imperial College London on (you guessed it) 15th October. There are going to be lots of speakers on lots of different types of science, plus a healthy dose of comedy, and it looks to me like it will be immense fun. You can get a ticket here, and use the code "friendofALD" to get £5 off - there's a "enter promotional code" box just above the big green Order button. It's suitable for age 12 and over, which sadly may exclude my mental age when it comes to jokes, but the rest of me will be there.

Also, on 15th October, there will be a book coming out. It's called "A Passion for Science", is edited by Suw, and is to fund Ada Lovelace Day. It will start as an e-book, but Suw hopes to have a paperback version too.

The book is about 25 people who broke with tradition to study science, technology, engineering or mathematics. One of them discovered pulsars. Another wrote the first computer program. Another used her illegal radio set to help the resistance during World War II. Another discovered that stars are made of hydrogen and helium.

You've probably guessed it: all these trailblazers were women (though we're not being too loud about this, so that those who don't think women can do science will still pick it up and maybe learn something. I'm assuming that you're not one of these idiots, since you're reading a blog that's obviously written by a woman). And here's my big news: I wrote a chapter about Cecilia Payne-Gaposchkin, who is my favourite ever astronomer. (I've blogged about her here and here.) I am very fond of Payne-Gaposchkin. Her discovery was, really, just as significant as that of Newton, Einstein or Darwin - what the Universe is made of - yet very few people know her name. She used some of my favourite pieces of science - the then very new quantum physics to take a new look at spectroscopy, the study of light and matter. Although she was kept as a lowly "technical assistant" for many years, and after her PhD had limited freedom to pursue her own research, she went on to make many more discoveries about stars, novae, and much more.

I love her for possessing many of my own "bad points" - she was quietly obsessive, moody, jealous, and terribly untidy. She - like me - particularly liked drawing together huge amounts of information from various sources, and putting it all together in a clear way. She was a kind, funny and wonderfully brave and compassionate person, fascinated by everything from astronomy to art to languages to cooking to woodwork to music to etc etc. I first read about her in Empire of the Stars and then, more compellingly, in The Magic Furnace (the latter is my favourite science book, by the way), and longed to know more. When I found her autobiography, that was one of my main motivators to study science more deeply and do an MSc in Astrophysics.

So, I've been researching Payne-Gaposchkin for the last three years, and plan to do a lot more. In fact, I wrote such a long chapter that poor Suw had to cut quite a bit of it out in order not to turn the book into "Cecilia Payne-Gaposchkin with a sprinkling of other amazing scientists squeezed in". But I hope to share it all with you in time . . .

In the meantime, you should definitely follow Suw and Ada Lovelace Day on Twitter. And Suw's feline owners, Grabbity and Sir Izacat Mewton. Happy Ada Lovelace Day next week!

Update: Check out the cover! I love it!

Update II: You can now buy the book! I hope some of you will - it's full of wonderful stories and inspiration.

Wednesday 11 September 2013

So I took cake to a police station last Saturday

It was going to be a good Saturday. I've had a very stressful summer, and I've been ill and had to miss a lot of things, but I was on the mend. That day I was going to have to myself. I was going to play games and perhaps do a bit of cooking and cleaning, but nothing major. I was going to be lazy and I was not going to worry. Well, I might be a little tense for a few hours: a few of my friends were going on a demonstration, but they'd said they were going to be careful and move away from anywhere that looked like trouble. They'd text me when it was over and they were safe. It was going to be fine.

I love old-fashioned games like Theme Hospital and Roller Coaster Tycoon. Roller Coaster Tycoon 2 has some pretty high targets to win the levels - "Have 3,500 guests in your park by the end of year 5" - so sadly you don't get time to enjoy the levels and build roller coasters bit by bit; there is, however, a tool to design them in advance. So I was playing around with types of roller coaster I don't usually build. Excitement rating this, intensity rating that, nausea rating the other. Oh, a text. From a close friend. "Kettled at Tower Hill approach. S with me. Arrest looks likely."

My insides shrank and everything around me seemed to fall away for a moment. My heart began to pound painfully. It was hard to breathe. There was nothing I could do. I could only send a supportive reply back, trying not to sound too scared, and attempt to carry on playing, but it was hopeless. I went onto Twitter to see what was happening. My hands were shaking so much I could hardly type. My phone, which is old and unreliable, kept saying "Message sending failed". I couldn't even send words of hope.

Twitter was well aware of the kettle. A picture began going round - the best description I saw of it was "Overkill much?" As you see, the people in it are very much outnumbered by police. I had no idea if that was where my friends were or whether there were other kettles too.

I soon found out that only a few of my friends had gone on the demo and that most, like me, were awaiting news. For a while things seemed to look up. The next text said: "Still kettled in a group of 50 people at Tower Hill Approach. Maybe won't be mass arrested because I can't see any arrest buses, only lots of cops, police horses and about 5 vans. I think they are just keeping us here."

It's true - you do breathe a loud sigh of relief. I felt a bit weak. But my brain was racing. They might be in the kettle for a very long time. Should I take some food there, to greet them with as they got out? Would that put me in danger too? Where were they - and why? What had they done to get kettled? What was going on? I knew my friends wouldn't do anything stupid like be violent . . . but I have heard some horrible stories of police accusing people of being violent - "Stop kicking me, stop punching me" - while they are standing still. You don't believe this kind of thing when you first hear it. But when you hear it from many sources . . . and when incidents such as Ian Tomlinson, Jody McIntyre, Alfie Meadows and Jean Charles de Menezes seem to be increasingly common; when you've been to Taking Liberties and seen the footage of police attacks on a road you used to walk up every day in Brighton; when your own close relatives have been shoved around, trampled on by a horse and forbidden to walk up the street they live on because they live near a football ground - well, those safe certainties start feeling cornered, and wherever they try to run, there's nowhere to go.

I asked my friends what I should do if they were arrested. I was told to tell another friend, and to call Green and Black Cross. They joked nervously about waving from the kettle picture and assured me that even if they were arrested, they would be OK. Messages were getting through very slowly - possibly, I panicked a few times, the network had been blocked, or more likely there was just a high volume of texts going back and forth. Then I heard that another friend had been injured. She has a long term spinal injury and is often in a lot of pain. She tried to explain this to the police, but a policewoman hit her with her baton so hard that she fell to the ground. Several of us tweeted to the @MetPoliceEvents account to ask that she be let out as she needed an ambulance. It was a long time before they let her go. One other friend was allowed to accompany her. It turned out it was a blessing in disguise, because as they got into the ambulance, several unmarked buses arrived and the mass arrests began.

Talking to another friend who'd stayed at home, I learned of a lovely activity called "arrestee support", where you go and wait outside police stations to help activists as they are released. They are often very hungry or thirsty, released into an area they don't know, and if they're especially unlucky they've had their possessions confiscated so are unable to buy bus or train tickets home. I had been sitting still in a fizz of adrenaline for the last few hours, and doing something positive would make me feel better, so I went to bake some little chocolate cakes. I'd bought a jar of Nutella only to find out I didn't like it much, so I spooned the chocolate cake mixture into the tins, put a teaspoon of Nutella on top of it, and then another teaspoonful of cake mix on top of that. I ended up with 28 little cakes, and ran back upstairs to hear of any news - had the police followed my friends into the ambulance, or had they been let go? - where should I take the cakes? - did anyone know?

It wasn't yet certain where the arrestees were being taken. I tweeted out to ask if anyone would need the cakes and initially got no reply. However, I heard from my friend who had been hurt. Her injury might well have been inflamed and she was in a lot of pain and keeping very still, but she didn't need to go to hospital. She was going to give it a few hours and then three of them were going to do arrestee support. A fourth friend and I asked if we could join.

I got a reply to my cake tweet advising me to ask Green and Black Cross. I was under the impression that they provided legal support, not cake delivery, but they promptly sent me a number to call. It felt most silly and surreal. "Hello, this is @PenguinGalaxy . . ." "Ah, are you the baking lady? Can I give you a call back in just a moment?" "Yeah, sure!" It was late afternoon now. Over two hundred people had been arrested. Twitter was bickering and the last few cakes were refusing to rise because they'd had to go in the bottom of the oven and had cooked too slowly. It was a mundane day. But I just felt I had to do something.

Green and Black Cross called me back and told me that people were being taken to four police stations: Colindale, Sutton, Lewisham and Croydon. I hadn't even heard of the first two and the line was bad, so I had to get them to repeat it. I told them my friends and I would like to help out. They gave me another number to call "to coordinate arrestee support". I said I would pass this on to a friend who has better connections than I do. I'm not very political, I'm not in any activist group - I currently don't call myself an antifascist or anything like that - and I would be a useless coordinator. I could simply see that a lot of people had been arrested for not very much and would need some help - and I wanted to learn more about what went on.

I passed on the information, waited a little while, and soon heard back that they'd decided which station to go to and that they'd meet me there. What with Green and Black Cross calling me "the baking lady", and there being ten times as many people arrested as there were cakes, I added some more supplies - tissues, some Pepsi given free with a pizza, plasters - and went via the supermarket where I bought crisps, chocolate, fruit juice and disposable cups. Money is very tight, but I found all the special offers.

It was a long journey to the police station, and it was in an area out of my pocket A-Z, so I had to rely on a pencil drawing I'd done using Google Maps earlier (my phone is too old to cope with maps). It was almost dark by the time I arrived. Finding the police station was easy, but none of my friends were there. I stood in the deepening blue air and looked around for them, then got out my phone - and saw one of them emerge from the building. I was astonished. What were they doing in there? Was it safe? Turned out, it was. They were all inside - details were not taken on the spot. The ones who'd been kettled apologised again and again for my worry earlier, even though they'd hardly asked for it to happen and had suffered much worse than I. I hugged them all emotionally - my injured friend very carefully - feeling a great rush of gladness that they were safe. Except one, who was very busy with a notebook, talking to a man I didn't know. He was shaking and visibly on edge; he was one of the arrestees, the first to be let out. He'd come on one of two large buses full of people. It seemed that Green and Black Cross had set my friend to collecting information for them - what people were arrested for, their bail conditions, when they'd have to go back, and did they have a solicitor or anyone who could give them legal advice?

It was a small waiting room in a super-modern building, looking rather like the leisure centre of a university campus or similar, and it was full of people. Several clearly spoke little or no English and seemed to be anxious relatives of arrestees. There were six seats, not enough for us all, and naturally much pacing about. The door kept opening automatically and each time its metal handles clanged loudly on the metal railings outside. I didn't really know what I could usefully do, so I opened up some of the bags and boxes of food. Most people didn't want anything, but the cake slowly began to disappear. I remembered the "peace" cake that got Mark Thomas's friend ordered to leave Parliament Square. (I keep meaning to take a cake with "peace" iced on it to Parliament Square just to see what will happen, but I haven't yet got round to it!) Bit by bit, I talked with my friends and began to learn what had happened.

I have not yet heard any reports of violence. It seemed that people were being arrested for "breaching sections 12 and 14" - all they knew was that they were walking up an empty street, some with banners, some without, and hadn't even met the EDL, when they saw police coming at them from all sides and were unable to escape. It seemed that certain areas had been designated as out of bounds without warning. Figures of arrests were between two and three hundred. The EDL (English Defence League, one of the two main far-right organisations in the UK, which has links to Anders Breivik) had chosen Tower Hamlets as their marching point - specifically Altab Ali Park - because of its large population of ethnic minorities and their apparent belief that it is "under Sharia law". (They do have some rather odd beliefs, such as that Brighton Pavilion is a mosque.) As far as we knew then, two EDL members had been arrested (I have since heard fourteen), including Tommy Robinson again. I had seen a tweet earlier that they were extremely drunk and were escorted by many police across London Bridge, but I don't know if it was true, or, if it was, whether this "escort" was protecting or restricting them or both.

It was a long time before anyone else was released. The next person out was a quiet girl who'd come in from outside London by herself. She hadn't been charged, but bailed and told to return in late October. She was extremely thirsty. The policeman with her directed her to the nearest train station, but by this time it was too late for her to get home. My note-taking friend told us how she'd felt to be arrested at a demonstration and then released in Basildon, which is way out of London, with no means of contacting anyone or getting home, but how she'd been helped by arrestee support.

Suddenly another bus arrived. It was a red, unmarked single decker, and it was full of people sitting very still. I learned later that they were all handcuffed. The kettling had begun some eight hours before now. I had never seen so many people with such miserable expressions. My friends ran outside and shouted greetings to them. I followed and tried to give them a supportive smile, wondering what they were all thinking, how much longer it would be before we saw them again. A policeman told us to move away and that we could be "arrested for obstruction". We were standing on the pavement, well out of anybody's way! "Are you proud of yourself, supporting fascists?" one of my friends asked him as we went back inside.

Gradually it got darker. The windows suddenly became mirror-like instead of transparent. A few more people were released. Their bail conditions forbade them to "engage in demonstration within the M25 where the English Defence League, English Volunteer Forces or British National Party are present". In other words, the far-right organisations may protest, but those who protest against them may not.

Some people released had heard of Green and Black Cross; others had not. One was in a state of shock because his solicitor had told him that his flat in the North of England may have been raided by the police - it was uncertain whether it had or not.

A couple with limited English arrived and waited a long time at the counter to be seen. I tried to work out whether they were more worried relatives or here for something else, but I wasn't sure. In the end, I just offered them cake. The woman took one with a huge smile and then began to cry. She didn't have any tissues, so I went and got her some as discreetly as I could. She managed to say "It gets better!" and soon after that, they were called through a door. I never saw them come out. Other relatives had less luck. Some were there from when I arrived to when I left three hours later. One woman who had initially refused any of our supplies changed her mind. Eventually a policewoman called four or five of them forward and told them that only one would be allowed to come inside to speak to them. I heard her say "Do you speak English?" and "I don't care" several times in quite an aggressive voice. It was a stark contrast to how wonderful the police had been the day I called 999 when a man had been attempting suicide at Leytonstone station. I felt bewildered and sad.

One of our group offered the girl who couldn't get home a place to stay. Two of us had nasty colds and badly needed hot drinks; my friend who'd texted me went off in search for anywhere still selling them. There was a toilet, but it had no lock and no paper; I made a mental note to bring lots of tissues next time I did arrestee support.

I went off in search of my coffee-bearing friend and when we got back, two more buses of arrestees had arrived. I went to the gates, unable to believe my ears - I had already heard that all the cells were full. There was a double decker and a single decker bus, and they were parked behind the building, the engines and lights still on, and nobody was coming out of them. Evidently the buses themselves were being used as holding cells. It was then that one of the recently released people - a remarkably cheerful person who'd come from the South of England and refused a cake due to being a vegan - told us that nobody was allowed to talk on the bus. "Sounds like school!" I said. He laughed. "Yes, exactly that!" We could only laugh and try to remain upbeat and strong. We were in shock, but would keep our spirits up for each other.

How could the figure be only up to three hundred, I wondered? It looked like nearly that many were at this police station alone. And people were only being released every half hour or so. How long would it take to release them all?

We all talked, a little. One of the arrestees rolled up his trouser leg. The worried relatives were intrigued to see it was covered with heavily inked telephone numbers. He explained that it's a standard activist tactic: pieces of paper and mobile phones can be removed, but your limbs cannot. My limited experience has taught me that you should use a thicker pen than a biro - upper arms are very soft.

I went home at elevenish, so as not to miss the last trains. I later learned that three of my friends stayed until 2am, when a new shift of support workers took over. Between some time before 8pm, and 2am, my friends helped fifteen people. (A couple more hadn't wanted to talk to us - understandably, since we could have been anyone.) Of these fifteen, three were simply members of the public who had had nothing to do with the demonstration, but had simply been walking up the street and then driven into the kettle. By about 9am the next day, Green and Black Cross tweeted that everyone was out of that police station. My estimates of how many had arrived were too high; "only" 286 people had been arrested - the largest number in one go since at least the student protests of 2010.

It was a slightly shattering experience. One assumes that you're safe from arrest until you break the law. I've yet to hear any evidence that the people arrested were even disruptive - none of the people that I saw released were charged with anything. That's not to say that I think antifascists are all completely peaceful. I don't. Actually, I don't call myself one because I know they include some very unpleasant people. I'd tagged along on one demonstration before and overheard some sexist and ableist remarks being made, as well as a lot of showing off. But the notion of antifascists being a screaming, violent, uncontrollable mob - the picture we get many times through the media and through other people's remarks - was utterly at odds with the calmness I'd seen on Saturday, the support and care people showed each other, the quiet and controlled behaviour. One would have thought that for 286 arrests, there must have been some kind of riot. But I have heard (only through rumours; sadly, when there is no trust, most information comes via rumour, so we can never be certain of anything) that mass arrests were planned that day. And one senses from the bail conditions that the aim is to put people off demonstrating.

Demonstrating is a fundamental human right. The EDL have the right to speak their minds, and so do antifascists. I have seen the sentiment that antifascists are removing the EDL's right to peaceful assembly by demonstrating and using phrases such as "they shall not pass". I have also heard the contrary sentiment that fascism and racism are illegal, so why should the EDL get to march at all? My personal take is the least "controlled" of all: that the EDL do have the right to demonstrate, and the rest of us have the right to tell the EDL that they are neither right nor welcome. To deny anyone the right to say what they think, no matter how horrible it is, opens up too many doorways to abuse (I wrote more about this here). But since the antifascists are not law-makers, they cannot forbid the EDL to assemble; they can, however, disrupt such assemblies - disruption often being a very peaceful and effective tool. But let's face it, choosing to march in Tower Hamlets is not abstract debate or a polite message to Parliament. If it's not a deliberate attempt to intimidate and inflame, I don't know what it is.

One of the arrestees told me that she was sure the police dislike the EDL and the antifascists equally. I have heard others claim that the police favour the EDL. I don't know. I only know that, last Saturday, I witnessed a very heavy-handed official response to people's expression of their views. And I know that since the ghastly Woolwich murder, some of my non-white friends are afraid whenever they are out in public. One has been stopped and held up for a long time arriving at Glasgow airport, while white people who were being loud and disruptive were waved through without question. The atmosphere is fairly easygoing here in Ilford, with its large Asian population - indeed, people in shops especially seem to be going out of their way to be extra nice. But when I go to other places, I feel the tension.

I have not named which police station I went to and have avoided revealing any details of my friends or anyone else there or marching. If you were there and would like to reveal yourself, please by all means do so, but please respect others' privacy.

And I hope you got some of my cake.

Thursday 18 April 2013

In sleep a king

. . . as a dream doth flatter, 
In sleep a king, but, waking, no such matter.
Ten years ago I would have hailed this as exactly what I wanted to say. This piece has been judged excellent, well thought out and a breath of fresh air by many people I like and respect. It claims that it is impossible to write fluently without someone jumping on you and accusing you of oppressing people who may be female, disabled, trans, gay, non-white, etc. That language itself is being ruined by attempts to be "correct". That what people says is being lost in accusations of oppressing someone, while in fact far more people who genuinely don't know what "correct" language is are being alienated and left behind.

When I was young, I hated political correctness. I hated racism even more, and made a point of spending as much time as possible with the international students. In fact, political correctness seemed to me to be racism, but with a shiny veneer: "Oh, I won't say 'black coffee', because it is a problem to be black, but I'm too polite to say so. I won't use any word which refers to your colour, positive or negative or neutral; aren't I nice?" To be fair, I did know some people a bit like that. I was also once publicly held up as a racist in front of a hundred-odd other people because I'd fallen into a deliberately set trap. I was distraught (especially when one of the people praised for their "correct" attitude then went on to say "that Paki" the very next day).

It makes me shrink to say this, but it's true: I was particularly upset that my friends would repeatedly talk about how unacceptable it was ever to even mention the word "Jew" or "Jewish" because that was not only racist, but pro-Holocaust. My family had been ostracised by some Jewish people - a very small minority, I didn't doubt then and don't doubt now - who had refused to speak to us, even to give us directions when we were lost, because we weren't Jewish. (At school, my dad had been in a football team of mostly Jewish boys, who had named themselves "The Smelly Yids"!) I was sympathetic in speech but irritated in private when a friend complained that the university campus made it hard for her mother to walk as she had weak ankles: did she want the whole place knocked down? (It was a campus largely made of steps and pyramids and walkways. An amazing place. But definitely designed without disabled people in mind.)

I look back on my younger self with mortification. Did I ever say terrible things about anyone just because I felt My Right to do so trumped political correctness? Did I make things worse for anybody? It haunts me. Which, of course, doesn't help anyone.

I think, now, that what I was seeing and hating was a caricature. Much like the caricature tabloids write of health and safety policies, which stop people buying cheese and saying "Christmas", rather than are enforced to save lives. Or of immigrants, who are here to take all our jobs and live off all our benefits (you know, in right-wing minds they can do both at once).

Caricatures can distract from reality. They divide and rule.

As Deborah put it in a talk she gave recently to Hackney Skeptics, it was common in medieval times for women to accuse other women of witchcraft because that was pretty much the only social leverage they had. If you're at the bottom and unable to confront those at the top, it's all too easy to turn on those also at the bottom with you. I'm pretty sure this is exactly what the government and tabloids want the working classes to do - to spit at disabled people and call each other scroungers, rather than take our grievances to the government and to large-scale tax avoiders.

Another problem was that I was very ill at the time. It was an invisible illness. No allowances could be made for me. As far as I know, there's no special insult for "person with a major intestinal disorder who suffers from nausea and pain and anxiety" (as there is for many mental conditions or loss of mobility, for example) that could be not used. There were no physical adaptations that could be made. There was nothing to help me. I was jealous of those who could be helped and were.

Looking back, those who forbade mentions of various races or colours were invariably white. The girl who told me not to swear in her presence because she was a Christian also boasted about how she had destroyed her mobile's sim card to get a new phone on insurance. My Ghanian housemate was happy to talk about being black - but that was years later; he was not party to such discussions. I never heard what Jewish people thought of anyone mentioning the word "Jewish" or "Jew".

Well-meaning people wanted to speak in their support. Other well-meaning people disagreed with how to speak in their support.

The voices that should have been loudest were not even there.

So there I was, full of my own problems and without awareness of those I didn't understand - that I had no way of understanding. Until circumstance made me understand.

Three years ago I found work in a charity that provided information and hired out mobility equipment to disabled people. It was "run by the disabled for the disabled". I was the only person without a physical or mental disability. It was the most supportive place I'd ever known. My physical problems (the pain and nausea and weakness) and my mental problems (my depression, anxiety, workplace phobia as a result of bullying, and lack of confidence) were accepted and no big deal, but my colleagues were always there to listen and support me. I found myself doing the same for them. And a new part of me began to blossom.

I was appalled by the rage I saw in some of the newsletters, such as Disability Today. They seemed to personally loathe anyone whose legs worked properly. But I was equally appalled by the slurs levelled at disabled people not only in the newspapers, but from a random man who took it upon himself to walk into the office and berate me for handing out blue badges to his neighbour who he was certain didn't need it. And I began to realise that slurs were spoken, judgments were made, policies were drawn up, without the involvement of the people they affected.

Perhaps one problem with knowing that others are disadvantaged is that decent people have an immediate instinct to speak up for such people. The trouble with that is that it gives those who don't actually have much knowledge a false idea of how much they do know. There's a point when you just have to say: I don't know what it's like to be coloured, disabled, or trans. And I have to shut up and listen.

There are men who write in favour of feminism, who speak volubly and passionately about how much they care and how anyone who thinks them sexist is hateful and misunderstands - but who will then ignore women's voices as soon as they don't like them. I doubt they realise they're doing this. They want to do good. They already get stick from those who disrespect their feminist stance, and this hurts, but they keep going. They genuinely mean well. Just as I meant well to say that political correctness was racism made respectable.

There are men who simply retweet women's words without comment, who chase away harassers, who protect vulnerable women even after their friends have been shot doing so, who don't tell everybody else what to do. These men are much harder to see.

A few months ago, a new website for feminist writing opened, and they asked me to submit an article. I wrote about my two sides of what I consider feminist activism: women in science, and Galactic Orchids. They turned me down. They wanted their first article about female genital mutilation to be from someone involved in the relevant culture. I was hurt - rejection always hurts - but they were right. I should be quietly supporting and amplifying voices of those actually affected. Not leading the discussion.

It wouldn't be right for me to tell my trans friends how to survive, or my non-white friends when to consider someone racist and when not. I don't know what that's like and it's not for me to say.

This is a difficult post to write, because if you're on Twitter you probably know there's been a big blow-up between prominent feminists over the issue of language. I have friends on both sides of the platform. Passionately so. One side says: they attack you if you don't know the words "intersectionality" or "WoC"; you can't open your mouth without them jumping down your throat. The other side says: you can be polite and they ignore you; you can get angry and then get labelled a bully. One side says: there's a core group of trouble-makers who are making this space less safe for women. The other side says: they just don't want to listen, they don't want to learn, their only solution is to continue oppression and marginalise anyone who dares disagree.

It is heartbreaking to be told you've used an oppressive word, such as "cretin", when you only meant "someone who has done something very silly and very funny" - and when you've just spent a huge amount of time and energy supporting someone with mental health problems, listening to them, pointing them to places that can help, leaving yourself drained. It is all too easy to leap to the defensive. "You KNOW I didn't mean that. Why do you assume the default position is that I'm ableist when all the evidence points the other way? Who cares about words over actions?"

But why spend an awful lot of time and effort for a cause if you're then not willing to listen those you're supposed to be supporting? Over something that really won't hurt you in practice? Calling out someone actually doesn't have to mean "you're ableist scum, I hate you and I'm going to shame you before the entire world. You will never live this down" - even though it feels that way. When people have pointed out I've used a word I shouldn't, they've generally only meant, "Please don't do that. I know you don't mean to, but it hurts, and it adds to the problem."

That's all I've meant when I've asked men (especially on Facebook) not to keep posting pictures or jokes that objectify women - that discuss us as if we're pieces of meat, that rate us by our attractiveness, that tell us to accept it was our fault for dressing wrong if we were raped, that we are too emotional and illogical to be scientists. Many are resistant. They know what they mean. I should keep quiet and accept it, right?

"Do call me out if I screw up, as I'm sure I must do from time to time, being white," wrote Scattermoon on Twitter. A different approach from defensiveness: Teach me. I will see it as teaching. Not accusing. I will grow.

Joining Galaxy Zoo and Skeptics in the Pub meant that I had to be very ready to accept correction if I ever made a scientific mistake. Being a feminist - and one who includes women (and men, and transfolks, and etc etc) of all colours and abilities and backgrounds, which is my current understanding of the word "intersectional" - means I have to be ready to accept correction, too. In my family we never used "nut" to describe mental health problems - it was often an affectionate word, sometimes actively complimentary, in praise for a really silly joke. But just as I learned a new language when I moved to Spain back in 2003, I learned a new language when I left home.

It really hasn't hurt to watch how I use the word, and similar words, now. To adapt a little is a very small price to pay for knowing a vastly more diverse group of people than I used to - and knowing so much more as a result.

It's true that lots of people don't know what "intersectional" means and there's no point assuming they do. That doesn't mean the word has to be rejected out of hand, though. New words do spring up. "Cis", for instance, to describe "not trans". "Straight", for example, to mean "not gay". Yes, language is complicated, and frankly, columnists, you can't please everybody - it just isn't possible. Any read of any comment section will demonstrate that.

As I read on a blog yesterday which I now can't find (if you know the one I mean, please post it in the comments!), it is very easy for a campaign to seem whiny and unimportant if you don't know what it's about.

And the only way to learn what it's about is to listen.

Monday 15 April 2013


Come take my hand and run swift with me,
Leap high till we skim over road and tree,
Till oil-painting fields fall fast down below
And wind burns our faces, and cotton clouds grow.

Come take my hand and fly round the world
Race faster than falling, up into the cold
Slingshotting us into the deep blue of sky
Soft pale horizon, dark airless roof high.

Hold my hand tight as stars stream overhead
And Orion turns cartwheels and our sheer speed has led
To our satellite orbit round Earth blue and bright
The landscape tingles with stars in the night.

The Moon and the space station make paths like a spell
We roll steady and safe in Earth's gravity's well.
Come take my hand and fly high with me
Join the dance of the planets in our galaxy.

I've never been satisfied with a poem I've written, but hey, it's always good to push yourself out of your comfort zone. Seriously, with space suits and considerably less gravity than the Earth's - say, a large asteroid - this is actually possible. Or a rocket. The reason things stay in orbit, be they moons or binary stars or the International Space Station, it's because there's a perfect balance of speed and gravity. Everything in orbit is in freefall, but moving so fast that the falling only amounts to being pulled around in a stable ellipse or circle.

Do you think, from the aeroplane window, that British fields look like oil paintings? I do. Spain, with all its olive trees, looks like black-dotted yellow graph paper. Norway looks like dark green papier mache, and Nova Scotia - which I think is the black-and-white icy mountainous area we flew over when I went to America two years ago - looks absolutely amazing.

This is one of my favourite ever pictures of space. I'd love to do this some day.

Monday 1 April 2013

Crowdsourcing a Galactic Orchids talk: What are your astronomy questions?

Why do stars live in galaxies, rather than being spread out evenly through the Universe? Where did the Big Bang actually happen? Doesn't the Moon pull on water and therefore affect us? These are just three questions I've been asked and have got round to answering on this blog (here, here and here, in the same order) - and now, inspired by Dean's Comic Relief crowdsourcing efforts, I'm inviting you all to send me astronomical questions out of which I might make a whole talk.

My most major astronomical activity these last few months has been Galactic Orchids, a series of talks to raise funds for the Orchid Project and Daughters of Eve, two charities fighting (in very different fashions) to end female genital mutilation. I have about seven talks now, but I'm running out of ideas for them, and would like to keep going in autumn 2013 - so I'd like your ideas, please! What puzzles or interests you about astronomy? What would you want to hear about?

Your question might have a short answer, such as: Why is a lunar eclipse red? Or it might be major, such as: What exactly have we done so far to explore Mars? So I hope to make an entire talk out of short questions, and I also hope to make a few talks out of longer ones. Feel free to suggest what you'd like an entire talk to be made of!

If you'd like to come, the next two will be Wednesday 10th April and Wednesday 8th May, both at 7pm at the Newington Green Unitarian Church in Stoke Newington. There'll be tea, coffee and biscuits available afterwards and a question and answer session - it's very informal. We began in October 2012 and have so far raised over £300.

You can ask questions or suggest topics by leaving a comment here, tweeting me or Galactic Orchids, or visiting our Facebook page.

Thank you very much!

NGC 5218 from the Sloan Digital Sky Survey. At Galaxy Zoo we call it "the rose".

Tuesday 26 March 2013

38 things you might not know about the Moon

(Unless, of course, you are extremely keen on the Moon, in which case you probably do. Anyway . . .)

1) Our Moon is the largest moon relative to the size of its planet in our Solar System. Some moons are larger - Titan and Ganymede, for instance - but are hundreds of times smaller relative to Jupiter and Saturn. This of course leaves out Pluto and Charon, which besides no longer belonging to the "planet" class are more of a several-body system. On that topic, our Moon is more than five times the mass of Pluto!

2) It's as bright as a sunspot and as dark as coal. A sunspot is a darker point on the Sun's surface. If you could isolate it, it would shine as bright as a full Moon - which looks extremely bright in the sky, especially when full. But its rocks are about the colour of coal. Its apparent whiteness is because it's nearby, and we see it contrasted against a darker space. Its albedo is roughly 0.1, which means it only reflects 10% of the light that hits it. (Ice is about 0.9, meaning it reflects 90% of the light, and charcoal about 0.04, meaning it reflects about 4%.) The Earth's albedo is about 0.3, though of course it varies from place to place. Mercury's is similar to the Moon's.

3) In pictures, the Moon is almost always drawn much bigger than it really is - because it is so bright and captures our imaginations. Its angular size in the sky is between 29.43 to 33.5 arcminutes, which is actually very small. The Andromeda galaxy appears six times larger than the Moon from Earth - but then, of course, we can't usually see that.

4) The size of the Moon appears to vary because of its elliptical orbit - and not because of where it is relative to the horizon. The famous "Moon illusion", the fact that the Moon appears huge when it's on the horizon, has been documented at least since Aristotle. Various theories have been put forward to explain it: one from Ancient Greece was that the Earth's own atmosphere had a magnifying effect. In fact, it doesn't - and you can check this for yourself by holding an object of fixed size next to the moon, at a fixed distance from your eyes. The cause is probably from the way we see the sky: we imagine it as fairly flat, or at most, a gently curving dome, making objects near the horizon seem further away than objects immediately overhead. There are also more landscape features like trees and buildings to compare the moon to on the horizon.

5) Actually, it's not quite simple. The Earth's atmosphere does have a lensing effect on the Moon which can turn it into funny shapes - but you need to be lucky to see it! It can be due to layers of air with different temperatures, such as here:

From the International Space Station, astronauts have seen a "squishy" Moon as a result of the Earth's atmosphere diffracting sunlight!

7) The Moon is 1/81th of the mass of the Earth, but its gravity is 1/6th. Why? Because of Newton's laws of gravity. (To be pedantic, the inverse square law specifically, which was not Newton's alone.) Gravity gets stronger the closer you are to the centre of something. If you have two bodies of exactly the same mass, but one is smaller than the other, the smaller one will have a greater gravity, though over a smaller area. This is why, in a binary star system where one star has died, the white dwarf, neutron star or black hole will often start accumulating matter from the star. As the Moon has a much smaller radius than the Earth, an astronaut standing on the Moon is much closer to the centre of the Moon than she would be to the Earth's standing on the surface of the Earth. Surprisingly, this effect is more significant than the mass of the body - double the mass and you double the gravity, but halve the radius and you multiply the gravity by four.

8) There is no atmosphere or liquid water on the Moon, meaning there is no weather. The escape velocity of the Moon is 2.38 kilometres per second (so it's much easier to fire rockets off the Moon than off the Earth). At Earthly and Moonly temperatures, this is easily low enough for all gases to escape immediately. (At a very, very cold temperature, such as Pluto and Charon, gases move far slower, so it's easier to hold onto them.) This has many implications . . .

9) . . . for example: Moon dust is dangerous to astronauts and their spacesuits! It's extremely abrasive - because no water has rubbed it and rounded it, the way rivers make pebbles smooth on Earth. It's very hard, because meteorite impacts give it a melted, glassy coating. This hardness and abrasiveness means it pierces spacesuits easily. It's very fine, and having no air or water to drive this fine dust around or turn it into soil, it stays there - static and clingy, getting into the Apollo craft and into the astronauts' lungs. The static comes from UV light which knocks electrons off the atoms and molecules. All this will need to be taken into account if we want to live on the Moon.

10) It has often been thought that there is water on the Moon - the Tintin characters, going there in the 1950s, see stalactites and stalagmites - and that hypothesis was correct: there is. It's ice, of course, and trapped within the rock - no rivers or lakes exist, and any water that seeped to the surface would immediately boil or be rapidly photodissociated. But absorption spectra by NASA's Moon Minerology Mapper show the presence of a tiny amount of water within the rock. This has wannabe lunar colonisers very excited indeed. Recently, researchers at the University of Michigan did a study on moon rocks which suggested that the water seems to have been there from the time the Moon formed. This is odd, because the Moon is thought to have been very hot when it formed, which would have boiled off any water. (The same, I suppose, goes for the Earth. Our water may have been brought via comets from the Late Heavy Bombardment.)

11) A "blue moon" is actually not a blue coloured moon at all, but simply the second full moon of any given month. Since the Moon's orbit is 27 days 7 hours 43 minutes, and your average month is 30 days and 10 hours, this doesn't happen often - every two or three years. Occasionally some Facebook page will tell you that a blue moon means something incredibly significant and spiritual. It doesn't: it's simply an inevitable lining up of human generated unequal series of numbers. Calendar months are entirely human choices. Sorry!

12) The Moon is red during a lunar eclipse because the light that reaches it is filtered through sunrises and sunsets. To visualise what is happening, look at this beautiful picture of Saturn:

Saturn's air itself is carrying the Sun's light around the planet (as the air does on a cloudy day on Earth). Earth's atmosphere does the same thing: the atmosphere around the edge of the planet carries the light on and diffuses it into Earth's own shadow. It's red light, for the same reason as sunsets are red: blue light is scattered and all goes off at an angle, leaving red light's path comparatively clear. There are also plenty of particles in the Earth's atmosphere, and particles tend to turn light redder. Light filtering through a sunrise and sunset has the most atmosphere to travel though. That's why people say there's "no protection" when you get sunburnt at noon: the Sun's light goes straight through the thinnest layer of air.

I made a silly little diagram to illustrate this for my March Galactic Orchids talk:

and incidentally, exactly the same thing happens when looking at spiral galaxies face-on versus edge-on:

(This lovely pair are NGC 4126 and NGC 3814. From the Sloan Digital Sky Survey telescope.)

13) We see perfect solar eclipses because of a wonderful cosmic coincidence: the Sun and the Moon appear exactly the same size. The Sun is 400 times larger than the Moon, but also 400 times further away. Actually, this varies - if the Moon is near apogee (furthest point away) due to its elliptical orbit during a solar eclipse, it won't quite block out the Sun, and we get the "ring of fire".

The shadow of the Moon on the Earth is actually surprisingly small. From the Planetary Habitability Laboratory:

(Eclipses are very emotional events. If you want to cheer yourself up, I strongly recommend watching this Sky at Night episode about Chris Lintott's trip to Turkey to see one!)

There is almost certainly no other planet on the Solar System where we could see such perfect solar eclipses - and this is in time, too, as well as space, because . . .

14) . . . the Moon used to be closer to Earth than it is now - and is moving away from us at the rate of 3.8 cm per year. We check this constantly by firing laser beams at retroreflectors placed on the Moon by the Apollo astronauts. As we know the speed of light, we can time how long the reflection takes to get back to us and get the Moon's distance to an accuracy of millimetres. In my lifetime, so far, it's moved away about 1.16 metres.

On average, that is. Its elliptical orbit varies by a huge amount more than that. But there's a slow progression. And the unavoidable conclusion is that the Moon used to be a lot closer to Earth than it is now. Tides would have been more dramatic; the Earth's own crust would have been under more strain, as would the Moon's. The friction this caused is why the Moon's face is always pointed towards us - and why we are heading the same way . . .

15) Earth's own orbit is slowing down, so one day we will always be showing the same face to the Moon, too. Our faraway descendants will never see a moonrise . . . But that will not be for a very long time.  At the moment, we only need to add a "leap second" less than once a year.

As Phil Plait put it: "I hope you liked 2008. Because you're going to get an extra 0.0000031689% of it today." (2008 was possibly the worst year of my life so I was not pleased, but the extra 0.0000031689% passed quickly!) As he explains, the Moon isn't the only influence - there's also the Sun, the fact that the Earth's structure is part solid and part liquid and generally uneven, earthquakes and tsunamis, and even the weather. So it's slow. But it seems that one day, a lunar orbit and an Earth day will be the same length - 47 of our present Earth days.

We know from fossil records and even rocks that the Earth's day was once 21 hours when life was very young, and 23 hours in the time of the dinosaurs. Coral is particularly good at showing this - they grow leaving marks like tree rings, marking days and years (or rather, periods of light and dark, and seasons, respectively). The older the records, the more days there seem to be in a year - indicating that days were shorter.

16) The Moon is speeding up! This is why it is receding from us, and how it will eventually only see one side of the Earth, as we do it. Essentially, it's taking energy from the Earth's rotation around its axis and putting it into its own orbit - like grabbing the hand of a spinning ice-skater. However, even though the Moon speeds up, it takes longer to complete its orbit, since it's further out.

17) The Moon may be responsible for the seasons. Some planets are very tilted (some ridiculously so, like Uranus); some are very sensibly aligned, with their equators on the same plane as the Solar System. Earth's is pretty tilted, and it keeps the tilt consistent as it goes round the Sun - hence, of course, the seasons. If the Moon was created in a giant impact (see later), this would have knocked us over; Uranus is thought to be tilted for the same reason. However, Earth also has a "wobble" (a very steady one; it's not going to fall over like a spinning top) which is shown in Milankovitch cycles. However, all these are steady and fairly minor, unlike Mars, which wobbles all over the place as its two titchy moons fail to exert any stability against the massive objects such as Jupiter pushing it around in the Solar System. The Moon has been shown to have a stabilising effect on the Earth's orbit - though this, much like the eclipses, will cease as it gets further away from us.

18) It may seem obvious, but art does not always capture it: the appearance of the Moon indicates where the Sun is, like an arrow. You will never see a crescent Moon looking like an open parachute: if the crescent is on its side, the "horns" will point upwards, indicating that the Sun is"below" the Earth's horizon. A full Moon indicates that the Sun is "behind" the Earth. My favourite ever scientist, Cecilia Payne-Gaposchkin, wrote in a 1954 astronomy textbook, agreed at the time to be the best in the world: "It is an amusing pastime to note the 'impossible moons' portrayed by some artists: a new moon high in the northern sky, for instance; a full moon near sunset in the west; or a crescent with horns pointed downward." (That is probably the American version of this book - I wonder if I have bought the only 1954 copy on the market?)

19) The Moon has a molten core and magnetic field. Both are very small - but it's enough to perturb the solar wind from the Sun. The molten core was found with the help of seismometers left by the Apollo astronauts. This is pretty interesting, since not all planets have a molten core or magnetic field - Mars's, for instance, has pretty much shrivelled up, and Martians have no protection from the solar wind.

20) Tides are caused by gravity. Nothing else. Contrary to what you may have heard, the Moon does not preferentially pull on water. It does not affect us "because we are mostly water". True, the Moon does have some cultural effects, hence the werewolf, the word "lunatic", and the Sussex police claiming that there's a rise in crime around the full moon. I've heard people tell me in all seriousness that they "feel different when it's a full moon", that they "felt really angry when the Moon was red during an eclipse", but the Moon isn't picking some of the molecules in your body and dragging them around whilst ignoring the others. I'm not going to pretend I know why these mood alterations seem to happen, but I suspect a lot of it's simply that we expect them. Moonlight is a wonderful, shivery thing, after all - I will never forget taking a walk in a moonlit wooded area around the lake on my university campus. The water was black and silver and the moonlight reflected astonishingly off the silver birch trees. The thrill was slightly marred by the fact that it was so muddy that one of my companions had wrapped his shoes in plastic bags . . .

The Moon's gravity - not to mention the Sun's - pulls on everything, including the Earth's crust. CERN had to take this into account building the Large Hadron Collider, if I recall correctly what was said on my visit there.  There are tides because water moves around easily. As for the Sussex police, I also recall Chris Lintott's comment on a podcast called "Living Space": "Anything to do with the Moon in Sussex has got to be Patrick's fault."

21) The much-missed Sir Patrick Moore wrote his first paper about the Moon when he was only 14. He was invited by a local astronomer, W.S. Franks, to come and use the Brockhurst Observatory which was very near where the young Patrick lived. Mr Franks was suddenly killed by a car knocking him on his bicycle, and Patrick was asked to take over the observatory. He presented a paper to the British Astronomical Association named "Small Craters in the Mare Crisium". You'll find the Mare Crisium on the far right here. "I sent it in, and was notified by the Association's Council that it had been accepted, but I felt bound to explain that I was not exactly elderly. I still have the reply, signed by the then secretary, F.J. Sellers: 'I note that you are only fourteen. I don't see that this is relevant'." (This, by the way, is exactly what you should be saying to young people interested in science.) You can read more in Sir Patrick's autobiography. (You can also leave a tribute for him here - and yes, he did play the xylophone.)

22) The darker areas of the Moon, "the man in the Moon", are called maria, meaning seas. Tell that to someone you know named Maria, if she'd be interested? The maria are of course not seas - they are in fact old lava flows, quite possibly made as the result of impact craters that filled with lava. There still seems to be debate whether the impacts caused an upwelling of lava or whether it was volcanism. They are dark because they are more iron-rich than the rest of the Moon's surface, indicating that they come from closer to the core. (Just like the Earth, the Moon has more iron towards its centre, because iron is heaviest, and it started off molten so heavy things sank to the bottom.) In this picture by Alan Friedman you can see a large lava basin which then received a later impact:

23) There isn't a "dark side of the Moon". There is a "far side" of the Moon that never points our way. But, as you can see for yourself, every side of the Moon experiences day and night with its rotation just as the Earth does. We can see the far side of the Moon, however, using spacecraft such as the Lunar Reconnaissance Orbiter:

24) The Moon does not, strictly speaking, orbit the Earth. Rather, the Earth and the Moon orbit a common centre of mass. This centre of mass, or barycentre, is just under 2000km below the surface of the Earth. That means that Earth goes round in a little circle, and the Moon goes round in a big one. (If they were the same size and mass, the centre of mass would be exactly halfway between them.)

The Earth and Moon feel equal and opposite forces: gravity balances a "centrifugal force" (I say that in inverted commas, because there's actually no such thing as centrifugal force, and the idle use of the term drives some physicists crazy. It's actually the law of inertia: the urge of the body to keep going in a straight line. If either body started going in a straight line, it would be going away from the other one. It doesn't, of course, because of gravity. When you whizz lettuce in a salad whizzer, it is flung against the wall of the bowl because it "wants" to go in a straight line, but the container prevents it from doing so). That's why we have two tides, not one. Water nearer the Moon feels the Moon's gravity more, and wells towards it. Water on the far side of the Moon feels the "centrifugal force" more, and moves towards outer space.

25) There are more maria and larger craters on the "near" side of the Moon that points our way, and the core is about 2km closer to Earth than the actual centre. It is tempting to conclude that all this is because the Earth's gravity pulled the heavy parts of the Moon towards us. But the Moon feels exactly the same effect as in the item above this: it has an equal and opposite "centrifugal force" pulling it away from the Earth as towards. It could be due to a massive impact (or several) coming from roughly Earth's direction; but we don't know. Perhaps one day we'll find out?

(It is not shameful, by the way, to answer a scientific question with "we do not yet know". It doesn't mean "scientists are stupid or lazy", but that the Universe is too big for us to have explored the whole thing yet. Otherwise we wouldn't need any scientists! Indeed, it's often when we think we're close to tidying up and claiming to understand the Universe that the greatest surprises of all occur - relativity and quantum theory, for example, or the accelerating expansion of the Universe. OK, rant over.)

26) The Moon is the second densest moon in the Solar System. The densest is Jupiter's volcanic moon Io.

27) Because of the Moon's elliptical orbit, we do get to see occasional corners of "the far side". This is called libration. Here, have a pic and get nice and dizzy.

There are other reasons for the libration: the moon's own axis is not quite at right angles to the plane of its orbit, so we see a "nodding" movement; and the fact that we're over 6000km from the Earth's centre, so we ourselves see the Moon from a very slightly different angle at the beginning and end of a night.

28) Phil Plait has a huge list of debunkations for conspiracy theorists who claim that the Moon landings were faked. You can read it here. I'll just go through one: the idea that upon launching, the Moon's dust "should have been blown around more".

Do an experiment. Next time you get out of the shower and the bathroom's full of steam, watch that steam for a while. Then blow on some steam quite far away. Or a balloon, if you desire; or a boiling pot of water or the kettle or a candle half a room away - whatever takes your fancy. You will notice that there is a pause, and then it will start swirling about. What did that?

Air, of course. The air from your lungs? Well, partly. But also all the air that's in between you and the steam. The air from your lungs knocked into air molecules, which knocked into more air molecules, which knocked into . . . well, on the Moon, this doesn't happen. Blown air, or blown anything, meets a vaccuum. Only that which is right next to the blowing gets touched. On the Moon, air will quickly dissipate into space.

For more lighthearted stuff, the Clangers are always willing to help.

29) For Moon observers, the best time to look at details is not at full moon, but when it's a crescent so there are lots of shadows. (This is only something I've been told. I'm a rubbish observer; I've used my telescope twice and then broken it!) Shadows show detail. Thank you Graham Bowes for this amazing image:

30) We've known for many centuries that there can't be air on the Moon, because its edges are sharp. Look at the Earth's own horizon, and it'll be misty, blue, and blurred. That's air getting in the way. You don't see that on the Moon. William Herschel, however, speculated that there might just be air in the craters - at the lowest points on the Moon's surface - and that aliens might live in these. He pointed out that at craters are on average 50% lit and may be lit from any angle, so alien buildings capturing the warmth of the Sun would probably be circular. Incidentally, Herschel has craters named after him on our Moon and on Saturn's moon Mimas.

31) Very occasionally, we see abrupt changes on the Moon, such as a spot turning brighter or darker or changing colour. These are transient lunar phenomena, thought to be caused by impacts, outgassing etc. You can hear a lot about the first ever recorded instance, in 1178, in Carl Sagan's "Cosmos". Some monks at a monastery in Canterbury saw "a splitting" of the very new crescent moon, and reported fire, smoke, darkening, and that the Moon "writhed" and "throbbed", "like a wounded snake". This was probably a large impact, and has been suggested to be the formation of the Giordano Bruno crater. Other odd phenomena include that static, UV-light-blasted moon dust, from number 9: the Apollo astronauts saw "twilight rays" towards the horizon, which was probably dust in a continually rising-and-falling state from the surface.

32) Going to the Moon made us much more aware of our own Earth. If you've ever spent a long time in a country other than your own, you'll know that you learn a huge amount about your own country, too. The first ever complete photograph of the Earth from space, "The Blue Marble", taken from Apollo 17 in 1972, and "Earthrise", taken by Bill Anders as Apollo 8 orbited the Moon in 1968, had a great effect on people's environmental awareness.

33) We're now pretty sure the Moon was formed by a giant impact on Earth, probably by an object the size of Mars. We can tell this from the fact that the Moon is made of fairly similar materials to the crust of the Earth, but not the core (it's less dense). Other theories of formation, historically, have included that it was captured, that the Earth and Moon formed together, or that the Earth was spinning so fast a piece of it bulged out and broke off!

It would take extreme luck to capture a passing body that was going at precisely the right speed to start orbiting the Earth, rather than colliding or simply escaping. If they had formed together, the Moon's iron core would probably be larger. This is also the case with the spinning theory. The giant impact hypothesis is supported by the fact that the Moon's composition is fairly similar to the Earth's crust. A more recent hypothesis is that there was a three-body collision, out of which the Earth and Moon formed together.

34) The temperature variation on the Moon is huge. At "night" - and a night lasts 2 weeks, since the Moon rotates at the same rate as it orbits the Earth - the temperature falls to -173 ºC, while by daytime at the equator, it rises to 127ºC.

35) There is a place near the Moon's south pole which is the coldest known place in the Solar System! There are very deep craters where sunlight never reaches the bottom. These have been measured to be -240ºC, 33ºC above "absolute zero" and 10ºC colder than Pluto. Of course, there might be similar permanently shadowed and even colder places in the Solar System just waiting for us to find them . . .

36) The Apollo astronauts brought back 2,415 separate samples of lunar rock, weighing a total of 380kg. You can go and see a piece of it at the Science Museum in London.

37) Nobody owns any land on the Moon. This has been decided in a treaty which specifically prohibits any country's sovereignity or its use for military purposes. So if someone tries to sell you a plot of land on the Moon (or to name a star after your loved one, or what have you), they are defrauding you - no matter how fancy the certificate you receive.

38) You can help explore the far side of the Moon and classify its craters with citizen science. Go to www.moonzoo.org.uk.

Thank you Graham Bowes for this ghostly galleon too.