Hallelujah, It's Raining Moon

If you're one of the long-suffering followers who only signed on for the science outreach, fear not ! This week I present the thrilling sequel to Blue Marbles (actually this perfectly logical extrapolation wasn't my idea but was suggested to me by some dude calling himself "Joshua K"). "Blue marble", of course, refers to the photograph of the Earth taken by the crew of Apollo 17. Fortuitously, treating the planets as marbles makes a convenient way to compare their sizes and masses. Scroll down to the bottom if you're after the video.

Having already done the gas giants, this time I'm looking at a more-or-less random selection of the Solar System's more solid worlds. Screw Venus - sure it's hot enough to melt lead all the frickin' time, the pressure from the atmosphere is the equivalent to being nearly a kilometre under water, and most of that atmosphere is carbon dioxide... but it's almost exactly the same size and mass of the Earth. This makes it incredibly boring. Let's move on.

Mars presents a more interesting comparison. About half the diameter of Earth, it would take about 9 times the mass of Mars to equal Earth. Mars is about the same distance away from us as Venus, but in the opposite direction - away from the Sun. While the temperature can be bloody cold, it can also be surprisingly warm. The thin atmosphere does not mean your eyes will pop out, no matter what Arnie says. He was right to demand that you be given "eeah" though, because you'd most likely die of oxygen starvation after a few minutes. Less dramatic than eye-sucking, and at least you'd enjoy the 1/3rd Earth gravity for a while.

Mercury isn't much to look at, but it's almost as hot as Venus and colder than Mars, constantly. It has no atmosphere to spread the heat around, so the side facing the Sun is roasting hot and the other side would make a taunton wish for thermal underwear. Mercury is just over a third the size of Earth, but you'd only need 18 of them to equal Earth's mass. This is pretty dense - in comparison you'd need 67 of the similar-sized Ganymede (Jupiter's largest moon) for the same mass. Mercury's high density could be because it's really just the core of a larger planet, with the lighter material having been blasted into space by a titanic collision billions of years ago.

Which brings us to the MOOOOOON ! Seriously, I don't care if you're at work, stand up and say the word, "Mooooooooon !" in a loud, dramatic voice. It'll make you feel better, I promise. If it doesn't, you probably have no soul and don't like the Indiana Jones movies. Err... anyway, the Moon, like Mercury, is a world of extremes. 120 C in the day, -150 C at night. But, like Mercury, it's really just a big rock, so let's move on to somewhere more interesting*.

* Don't misunderstand me. I would maim and injure innocent people by the dozen for a chance to go to the Moon. It's all relative.

Europa ! Yeah, that's pretty interesting. Jupiter has four moons that anyone cares about, and sixty-odd smaller ones that just generally faff about. The smallest of the moons worth paying attention to is Europa, which is fractionally smaller than our own Moon but quite a lot lighter... being partly made from water. Beneath its Hoth-like surface may lurk a liquid ocean. It's even spouting jets of water into space. This, to borrow from the great Bill Bryson again, is a "You must go at once, take my car !" discovery. Or it bloody well should be, anyway.

But I'm not here to blather on about alien fish. Let's skip over the methane oceans of Titan and the nitrogen volcanoes of Triton and head for the world best known for making the astronomy community look like a bunch of morons : Pluto. Even smaller and lighter than our Moon, the discovery of numerous similar objects lead to a redefinition of the world "planet"*. But Pluto is actually a pretty neat place in its own right. Cold, dark and incredibly lonely, it sometimes gets warm enough to thaw some of the frozen nitrogen and methane and produce a thin atmosphere. It also has a giant moon, Charon, which would appear at least seven times wider in the sky than out own Moon does.

*This was because astronomers felt it would be too difficult to cope with more than nine planets because they'd never remember all their names. And that's how we ended up with the world "planet" now having the most ridiculous definition possible. That's what you get for listening to Neil de Grasse Tyson.

We'll know a lot more about Pluto next year when the New Horizons probe whips past. A few months before that, we'll also get our first look at Ceres, the Solar System's largest asteroid. About 950 km across, this tiddly little world is roughly the size of Britain. Its surface gravity is over 30 times less than on Earth, so leaping 10 or 20 metres in the air would be no problem. A world-class bowler could throw a cricket ball about 5 miles, before realising that cricket would be even more boring in low gravity. Golf would be even more tedious, though pole-vaulting and basketball would become a lot more interesting.

Of course, you can also see all of this in animated form, because it's always fun to make it rain planetoids.

Why Dr Who Shouldn't Be A Guilty Pleasure

I like Dr Who. There, I've said it. And now I'm going to justify that.

One of Battlestar Galactica's greatest features was that there was absolutely no reset button, ever. If something went wrong, it stayed wrong. Main character killed ? That's it, they're dead*. But BSG wasn't really sci-fi. In most genuine sci-fi, as in Star Trek, the rules of the fictional universe may not be quite the same as in the real world, and often they can be circumvented (albeit usually in an interesting way) when they become... inconvenient. Main character killed ? No problem ! Get them cloned, or travel back in time, or hop into a parallel universe where they're still alive, or bring them back as a hologram, or heck, just make them come back to life, etc. etc. etc.

* Except for certain killer robots.

Sometimes, resurrecting characters can open up whole new storylines.
Even if those characters are complete smeg-heads.

Dr Who is at the very opposite end of the realism spectrum from BSG. There are no rules, only guidelines. Dr Who is to scientific plausibility what 300 is to historical accuracy - sure, there may be some occasional nods in that direction (even some very good ones), but they're nearly irrelevant. This is not a show where plausibility or even believability, let alone possibility, is much of a factor. And while that's what made 300 so stupid I wanted to vomit, somehow it's also what makes Doctor Who great.

Sci-fi realism spectrum

Not giving two hoots about scientific accuracy gives the show tremendous creative freedom. The show can endlessly re-invent itself without fundamentally changing. Ghosts ? Planet-sized aliens ? Katherine Jenkins singing songs to flying sharks ? Anything goes. It's essentially an exploration of an infinite universe, where everything that can exist, no matter how ridiculously unlikely, does.

Rarely have the words, "DEAL WITH IT" been more appropriate

The thing is though, the real universe is full of giraffes, exploding stars, Scarlet Johannson, worlds covered in methane, pandas, stars so dense they slow down time, and cabbage. We can only survive in a minuscule region of space barely five miles thick, on top of a rock hurtling around an almost 100,000 mile-wide ball of plasma, and we think this is normal. Anyone who thinks science fiction is nothing but escapism should have their head shoved into a telescope until they realise just how dreadfully, pitiably small the so-called "real world" is.

And that's one of the principle themes of the show - the idea that exotic is a relative state. If you've lived on a world covered in methane, the idea of just walking to the shops to buy some milk would be unimaginably weird (I lived in a place without streets, which for me was akin to living without trousers - just not natural). Or, as the Doctor would say, "No other race in the galaxy would think to invent edible ball bearings !"

This is actually very important... no, not the edible ball bearings, I mean the morality of the show. Before Stephen Moffat got his hands on it, the Doctor's assistants were by and large ordinary, normal people. Rose is a complete chav. Martha is about as boring as anyone you'll ever meet  And then there's the hugely underrated Donna Noble, a woman whose utter normality is best described by her luckless, reluctant, short-lived fiancé :

"And then I was stuck with a woman who thinks the height of excitement is a new flavour Pringle ! Oh, I had to sit there and listen to all that yap yap yap. Oh, Brad and Angelina, is Posh pregnant, X factor, Atkins diet, feng shui, split ends, text me, text me, text me - dear god, the never-ending fountain of fat, stupid trivia !"

With characteristic lack of subtlety, the Doctor puts it scarcely more politely :
Doctor : Weird. I mean, you're not special, you're not powerful, you're not connected, you're not clever.... you're not important.
Donna : This friend of yours, just before she left, did she punch you in the face ?

Compare this with Star Trek, where we rarely see anyone who isn't the best-of-the-best being allowed to have adventures.

With Donna in particular, we have a genuinely normal person who's not (unlike Martha or Rose) falling head-over-heels for the handsome stranger. Moreover, she's a very strong female character who's not stunningly attractive, something which is worryingly rare in mainstream sci-fi. Jenna Louise Coleman may be awfully nice to look at, but her character is pathetic compared to Donna, who's more than a match for our Gallifrean hero. For example, at her wedding :
Doctor : Hold on, what are you dressed like that for ?
Donna : I'm going tenpin bowling. WHY DO YOU THINK, DUMBO ?
Or, later on :
Doctor: The last time, with Martha, it got complicated. And that was all my fault. I just want a mate.
Donna : You just want to mate ?
Doctor: I just want a mate !
Donna : You're not matin' with me, sunshine !

The writers apparently thought Clara was pretty
enough that she didn't need much of a character.
This is true, but it's still a terrible mistake.

(As an aside, for more on the Doctor's companions, this article is worth a read. It certainly has a point that too many of the companions are pretty girls, though personally I think most of the article is an overly-harsh assessment. Companions in the Moffat era, however, do have a worrying tendency to have their entire lives defined by the existence of the Doctor, and have almost nothing to offer by themselves. Which only ends up weakening both of them.)

But anyway, rather than being revealed to actually have some sort of uber-epic alter ego all along - as with later companions - Donna (like Rose and Martha and Mickey) becomes important through her own actions. Yes, it takes a little help from an alien in a magic box. The Master calls the Doctor, "the man who makes people better", but he doesn't do this by mystical forces or mind control. Rather, he does it by showing them that there's more to life than they thought, and giving them a chance to demonstrate their own innate abilities. Slowly, they realise that they're not normal and never have been, because there's no such thing - exotic is indeed a relative state.

Mind you, some of them remain resolutely gormless.

Donna : What am I supposed to do ? I'm nothing special. I mean, I - I'm not... I'm nothing special. I'm a temp ! I'm not even that. I'm nothing.
Rose : Donna Noble, you're the most important woman in the whole of creation !

This tendency to treat the ordinary as extraordinary is complemented by the reliance on the principle that any sufficiently advanced technology is indistinguishable from magic. As a result, Dr Who can often feel closer to magical fantasy iiiiinnnn spppppaaaaace than true sci-fi.  Yet sci-fi it very much is, far more so than BSG. This is exemplified by the episode The Satan Pit. Our suit-wearing hero finds himself confronting a creature claiming to be Devil itself, originating from "before the Universe" :

"I believe, I believe I haven't seen everything, I don't know. It's funny, isn't it? The things you make up. The rules. If that thing had said it came from beyond the universe, I'd believe it, but before the universe? Impossible. Doesn't fit my rule. Still, that's why I keep travelling. To be proved wrong. "

Wow. Stuff like this is what makes up for the retarded episodes where the Doctor fights a giant wasp*. Seriously, this is a much misunderstood part of the scientific process. Proving existing theories wrong is what science is for (although this is present in many other si-fi's, it's rare to hear it stated so directly). Well... "wrong" is perhaps an unfair term. "Incomplete" might be better, because theories are by definition well-tested, and in a sense can't really be said to be "wrong", as such.

* Or the one with child acting so bad it'll give you a hernia. Or the one where people's faces get smoothed over but they're still able to breath. Or the ridiculous Slitheen. Sadly, it must be said that Doctor Who suffers from a high number of episodes which are just god-awful. As Donna says so the Doctor, so I say to the writers : "Sometimes you need someone to stop you."

To give an example, take Newton's theory of gravity. Works tremendously well for most aspects of everyday life, like dropping apples. Does a pretty dang good job in the Solar System too. But it's not quite good enough to describe the orbit of Mercury, and it's just not up to scratch for GPS satellites. Einstein's version doesn't have these little problems.

But relativity also does something far more profound than dotting the i's and crossing the t's of Newton's model. You can't use a few grams of matter to flatten a city in Newton's universe, but you can in Einstein's. Even more spectacular are the consequences that we haven't been able to explore yet - relativity allows - in fact, necessitates - time travel. And that's why being wrong can be the most wonderful and terrible thing in the world. Only when forced to let go of your old ideas can you begin to consider new ones.

Err.... "Science, it works, bitches" ?

The Doctor's attitude is resolutely scientific, even when things appear to be flat-out magical. Like any scientist, he's wrong at least as often as he's right, and delights in it. Being wrong doesn't make him give up and believe in magic - it makes him come up with new and better explanations. I contend that  Dr Who is a science fiction show in the sense that it portrays a fictional scientist dealing with - and this is the important bit - fictional science. The Whovian universe may have rules hiding in it somewhere after all - they're just completely different to what we currently think the rules of the real universe are.

But there's more. Beyond the feel-good factor of treating ordinary mortals as important, the show has a morality-tale aspect that hasn't really been seen since Star Trek. The Doctor rarely carries a weapon, abhors guns, and - though he doesn't always succeed - will usually attempt a peaceful solution, sometimes at tremendous cost.
Dalek Emperor : "What are you, Doctor, coward or killer ?"
Doctor : "Coward ! Any day !"

He's also firmly anti-establishment, which I think is pretty darn important in a prime-time family show. The last thing we need is for children to grow up venerating politicians.
Doctor: Don't challenge me, Harriet Jones. 'Cause I'm a completely new man. I could bring down your Government with a single word.
Harriet Jones: You're the most remarkable man I've ever met. But I don't think you're quite capable of that.
Doctor: No, you're right. Not a single word. Just six.

Finally, it also fulfils another vital role that Star Trek pioneered : it challenges social taboos. Science fiction is the ideal vehicle for this, because the audience is already expecting to be shown new ways of living. Star Trek had a black, highly capable female communications officer and the first inter-racial kiss and a Russian at the helm during the Cold War. These are impressive achievements. But it somehow never quite managed to tackle homosexuality, even in Enterprise, which was much the most gung-ho sexy Trek show.

Because this scene is sooo necessary to the plot.

Dr Who features gay characters all the time. They're just thrown in there, being just as heroic and inept as everyone else. In a universe of flying sharks and werewolves, no-one in their right mind would judge anyone by their sexual orientation. Most importantly of all, this is a family show. And you know what's absolutely fantastic about that ? No-one cares !

That's what I call social progress. Bravo, Doctor. This is definitely something that deserves to be celebrated. And right now, this should be actively promoted in countries where such matters are still - in defiance of all rhyme and reason - considered taboo, like Russia and Uganda. Showing us in family-friendly way that all people, no matter how chavy, or boring, or feisty, or stunningly good-looking, or gay or straight or just generally all-round curious, or even if they're Kylie Mynogue, that none of these people are ordinary and all equally valuable - that's a message which still matters. Well done, BBC, well done.